50. The Naitve Meadow Experiment – Drought Rebound

The Meadow Experiment has now been through many phases, with the first plantings installed over 4 years ago.  For most of its life there has been a serious drought here in California, so the plants have been well-tested for how they do in that environment.  But we are now emerging from a very wet rainy season, ending the drought, and the meadow has responded with a gorgeous burst of growth and flowers.  As you can see below all the plants have put on new growth and things are so lush that the stone spiral is mostly obscured.

When viewed at eye level the plants are a beautiful chaotic mass of flowers and foliage:

Yarrow and Poppies
The White Flowering Yarrow plants (Achillea millefolium) have shot up quickly and are in full bloom.  They are giving the fast-growing California Poppies  (Eschscholzia californica) a good run as they compete for light and space.  The Poppies were started from seed but at this point are almost a weed in this garden, spreading extremely fast and laying their branches down over top of the other plants – but I’m not complaining, the many flowers are great!

White Sea Thrift
The rain also did wonders for the White Sea Thrift (Armeria maritima ‘Alba’) in the corner of the meadow reserved for lower plantings.  Except for a few ones only recently planted they are full of lovely puffy white flowers on stalks.

Outside the Meadow
It is a great spring for all the gardens of the Bay Area and I couldn’t resist showing a few photos of the rest of the garden.  The purple Iris (Iris macrosiphon) is having a great blooming moment, and my little hillock of well-draining soil is looking great with lots of colorful succulents, grasses and a couple of Monkey Flowers (Mimulus aurantiacus ‘Eleanor’) in the background.


The challenge this spring is to keep the faster growing plants from overtaking the grasses and the Buckwheat (Erigeron sp.) which should have their own moment of peak beauty later in the summer.  So great to see the garden go through some hard dry times and then bounce back so beautifully!

Posted in Experimenting | Comments Off

49. Rhyne Designs’ 4th Anniversary

I am very excited as Rhyne Designs move into its 5th year of business, with lots of great things accomplished in the last year and more ahead.  Amazing to think that just one year ago (even 6 months ago) California’s drought appeared to have no end.  Now after months of record rainfall we are about to have a nice green and flowery Spring!

Built Work in 2016
The wet weather slowed down construction for a couple of Rhyne Designs’ projects as 2016 ended, but there were a few that finished up last summer.  In the Napa Valley I was pleased to see the landscape for a new home in the vineyards take shape.  To complement a nice modern architectural design the landscape uses board-formed concrete walls and geometric concrete paving patterns, along with artificial turf and gravel gardens to save water.

In Berkeley, we saw the installation of a fun backyard design with outdoor living spaces to complement a wood barrel-shaped sauna.  The design starts with a wood deck adjacent to the sauna, followed by a decorative gravel area for the fire pit, and a more low-key decomposed granite material for the secondary spaces.

Rhyne Designs has been working on a few different yards in the Moraga area, updating gardens several decades old.  The back yard shown here had a good overall structure so the design focused on reducing the clutter, unifying the materials palette, and generally simplifying the layout for a more open and relaxing space.

Another Napa Valley project that will finish as soon as things dry out is a new front entry for a beautiful 2 acre property.  This includes entry walls and a gate, as well as a grove of field-dug Olive trees, creating a modern style entrance to match the recently built house.

A multi-house project in Oakland as well as one in Walnut Creek are also finishing up as we speak, as well as a project in Belvedere that is shaping up very nicely.  I hope to get some good photos of all these projects as the Spring blooms come out.

Designs in Progress
Complementing the work under construction are several exciting projects at or near the end of design, lined up for installation this summer.  I have been enjoying working with the architect Stephen Willrich on an estate house north of Napa with many great features.  The house stretches out into the site to create many beautiful indoor-outdoor connections and pleasant outdoor rooms for enjoying the fine views up the valley.

Rhyne Designs is also working to finalize the design for a nice property just outside the city of Sonoma.  A new and very modern house by New York architect Thomas Hanrahan will sit at the back of a long narrow site in order to maximize the views.  The landscape design complements this with a clean and simple design that includes an Olive lined driveway winding through a large flowering meadow.  The meadow creates a nice low planting mass and extends over and beyond the mounded septic drain field in the center of the site.

I also had fun helping a client envision the possibilities of her big front yard in San Pablo.  With so much space, she wanted to consider how it could be put to use as a community asset.  The thought is to have space for food to be grown by local youth groups, and to hold classes on sustainable gardening and related topics.  I created a fun concept plan with a wavy spiral walkway that draws you into the site and becomes a focal point for gathering.

Racing into Year Five
These are just the highlights of a very busy 2016, as Rhyne Designs continues to grow and build on the many-faceted experiences of the business.  All the rain this winter has given 2017 a soggy start, but I’m already seeing indications that it is going to be busier than ever, with a list of projects just waiting for dry weather to break ground.  I’m looking forward to a great year ahead!

Posted in Design | Comments Off

48. Mulch

The first thing I look at when I see garden plants suffering is the soil surface – does it have a protective mulch layer?  All too often the leaf blowers of the world have whisked the bark out of the planting beds, leaving bare soil.  Mulch is an essential part of any garden with many uses and benefits.  I’ve mentioned some of these benefits in other blog entries but now it is time to put the spotlight on mulch.

What is Mulch?
Most people think of mulch as bark chips, but in fact the broader definition of mulch is “any material spread evenly over the surface of the soil to enhance the growth of plants and the appearance of the landscape.”  This material can be many things including: gravel, recycled yard waste, cardboard, or one of many wood products.  For the majority of garden situations, the term mulch refers to some type of bark chips that are placed on top of the soil in planting beds.  These bark chips mimic the natural ground cover in forests in many ways and provide similar benefits.

Benefits of Mulch
Bare soil in a planting bed is simply not good for the health of the plants or the soil food web.  A layer of bark mulch over planting area soil, 2 to 4 inches thick, has many benefits:

  • Soil moisture – having this layer over the soil prevents moisture from evaporating from the soil surface, preserving it for plant roots.
  • Soil temperature – mulch also blocks direct sunlight from the soil, keeping it cooler and more hospitable to root growth.
  • Weed control – weed growth is greatly reduced with mulch by keeping sunlight from the soil surface and physically blocking their growth.  Mulch also makes any weeds that come through easier to pull out.
  • Erosion control – the mulch layer also helps to slow down water flowing across the ground and protects the soil from being washed away.
  • Reduced soil compaction – the spongy nature of mulch also keeps the soil from getting compacted by foot traffic.
  • Improved soil health – bark chips decompose over time and add organic matter and nutrients to the soil.
  • Visual appeal – it is also simply a nice looking layer to add to the garden.  It helps visually unify the planting beds and give things a cleaner, neater appearance, especially with new plantings that are still small.                                      

Potential Drawbacks of Mulch
In my opinion the benefits far outweigh the drawbacks, but there are a few potential issues with the use of bark mulch:

  • Nitrogen absorption – some bark mulches are low in nitrogen and if mixed in with the soil can absorb nitrogen, depriving plant roots of this essential element.
  • Unwanted elements – it is important to know where your mulch comes from and avoid bringing in things like diseases and weeds.  Commercially sold mulches are not likely to have any issues, but mulch made from chipping trees does have the potential to transmit diseases like Sudden Oak Death.  Always confirm with the source that they are confident that no diseased material was used to make the mulch.  (In the San Francisco Bay Area there is a widespread awareness of these issues that minimizes any problems with recycled mulches.)
  • Fertilizing & compost – mulch does get in the way of applying fertilizers or compost to the soil surface.  You don’t want to put the fertilizer on top of the mulch, it will absorb it and pass it on to the soil much more slowly.  However it is usually easy to rake back the mulch before applying a fertilizer.
  • Floating – heavy rain can create temporary ponding and water flow across the ground, and bark chips can float up and travel with the water.  This can create piles of mulch in low spots, sometimes blocking drains.  This usually means you need to take a little extra effort to rake the mulch back in place after storms.  Using dome-top (“atrium”) drainage grates with small openings will help keep the bark from creating blockages. Bark mulch should definitely not be applied in drainage swales, various types of rock mulch can be used in its place.

Types of Bark Mulch
Bark mulch comes in several types, with variation in size, color, and source.  For general planting beds I prefer a 1” or smaller fir bark mulch as a balance between providing the maximum benefit and nicest look.  However the larger sized bark mulches in the 1” to 4” range are generally better at blocking weeds.  They also last longer since the bigger pieces take longer to decompose.  There is a trend of adding color dye to commercially sold mulch – in my opinion this is a waste – it looks artificial and regardless of what the suppliers claim, it adds an unnecessary chemical to the mulch that goes into your soil.  An excellent alternative to commercially supplied bark mulch is recycled content mulch.

Recycled Content Mulch
There are two general types of wood mulch with recycled content – Green Waste Mulch and Recycled Wood Mulch.  Green Waste Mulch comes from tree removal, tree trimming, and other plant clippings that normally go into landfills as a waste product.  This material is shredded into appropriate sized chips for use as mulch.  It is produced by commercial tree trimming companies such as the Green Waste Recycle Yard in Richmond.  City tree trimming crews also provide this sort of mulch for homeowners, here in the city of Albany they regularly deposit piles in public spaces where anyone can load up for home use.  Recycled Wood Mulch turns construction wood waste into mulch sized chips for garden use.  The trash collection company Waste Management produces this mulch locally “from 100% recycled, clean, untreated lumber”.  These mulches are without a doubt the best to use in terms of landscape sustainability and overall environmental health because they take local waste products and turn them into a beneficial material.  This keeps a huge amount of material out of landfills and eliminates the negative impacts of trucking over long distances.

I’ve focused here on the most common type and use of mulch, bark in a planting bed, but there are many other variations.  Sheet mulching is a process I’ve described previously as part of my Native Meadow Experiment.  Loose gravel is also a type of mulch I use often, it gives a nice clean look to a planting area, but it does not have the full range of benefits that you get from bark mulches.  Recycled rubber mulch has some applications in commercial situations but comes with its own set of pluses and minuses.  Fallen leaves and grass clippings also have mulch-like uses and benefits.  Don’t let those leaf-blowing gardeners get out of control in your yard, keep your soil protected with a nice thick layer of mulch!

Bay Friendly Gardening Guide  and  A Bay Friendly Landscaper’s Guide to Mulch

State of California – Cal Recycle  information on mulch benefits:

Green Waste Recycle Yard, Richmond

Waste Management Mulch Products


Posted in Plants | Comments Off

47. What are those? Oak Galls

You see these ball shaped things on Oak trees all over the San Francisco Bay Area.  They are especially noticeable in winter time when deciduous Oaks have no leaves.  I get asked all the time what these are and what to do about them.

They are called Galls, and it may be hard to believe but they are actually homes for the larvae of tiny wasps and other insects.  The most notable ones seen around Oak trees are ball shaped growths like the above pictures.  These are Oak Galls, or Oak Apples, and they serve as the homes for the development of wasps from the family Cynipidae.  These are very tiny wasps – 1 to 8 millimeters in size.  They form when an adult wasp lays eggs into the tissue of the tree triggering a swelling around the eggs.  When the larvae emerge from the eggs they further stimulate swelling and create the Gall, an almost tumor-like growth of tree tissue.  This structure protects and nourishes the wasp larvae as it grows into an adult wasp.

A Wide Variety
It is amazing how many different varieties of insects use galls as a part of reproduction, approximately 800 different types just on Oak trees in North America and over 200 wasp species that associate with California Oaks.  There are also a wide variety of shapes and locations for galls, with some interesting spiky pink ones, cup shapes, sea urchin shapes, very small ones on leaves, and many others.  Not to mention that there are also insects that invade and parasitize the galls of other insects, all part of that wonderful web of life we are a part of.


A Hazard to the Tree?
It is generally thought that galls don’t harm Oak trees unless there are other stress factors already weakening the tree.  Some birds are natural predators of these wasps and usually there is a balance of predator and prey that keeps the gall wasps from becoming overpopulated to the point of causing problems.  However there are cases of extreme infestation where treatment may be needed.  Heavily infested branches can be removed in the early spring and disposed of to prevent the wasps from developing.  There is a chemical insecticide called carbaryl that can be sprayed on trees, but like all insecticides this should be a last resort since it kills other beneficial insects and is a toxic carcinogen for humans.

A Hazard to People?
Because the wasps are so small, and they do not sting, the insects are not thought to be a hazard to people.  The galls themselves are sometimes called Oak Apples, but they are definitely not tasty.  Apparently they contain tannin compounds and have a bitter taste, but I have not read anything about them being poisonous.  It is said that they were once used for inks and dyes, and even cleaning wounds.

Beneficial Insects?
I couldn’t find much about the benefits of having these insects in your garden. In part it depends on which of the hundreds of insects that make galls you are talking about.  There are definitely wasps that prey on other insects that damage plants such as aphids and caterpillars, so it seems like a good thing to have a few gall wasps around.


I can’t help but wonder about the connection between different meanings of the word “gall”.  In a way these wasps do have some gall in using the tree to create a home for their eggs!  I wonder if there is any etymological connection here, perhaps one use of the word led to the other?

Oaks of California, authors Pavlik, Muick, Johnson and Popper

Sunset Western Garden Problem Solver,  by the Editors of Sunset Books

KQED Science article: What Gall!  The Crazy Cribs of Parasitic Wasps, by Craig Rosa https://ww2.kqed.org/science/2014/11/18/what-gall-the-crazy-cribs-of-parasitic-wasps/

Wikipedia article on Gall Waspshttps://en.wikipedia.org/wiki/Gall_wasp

Posted in Plants | Comments Off

46. Spring Green

The Spring Equinox has just passed, and Spring is definitely upon us here in the Bay Area!  The hills are once again coated with an amazing bright green that signals the rapid growth of grasses and wildflowers.  This is looking like our best spring in a few years because of all the rain, especially the heavy rain we just got in the second week of March – perfect timing for St. Patrick’s Day!


I was able to get out for a hike in the Crockett Hills Regional Park a few days ago and take in some nice views of the green hills and the San Francisco Bay beyond.  Growing up in Tennessee I remember a very lush environment rich with many shades of green that lasted spring through fall.  However, here in California the green of spring seems all the more intense because of the contrasting golden brown that happens just as soon as things dry out.  All these grasses and wildflowers are racing to flower and produce seed before things get too hot and dry.

These green hills exist as a grassland in part because of cattle grazing, but the typical plant community native here is the Coast Live Oak Woodland.  Without grazing, there might be more scrubby shrubs on the hilltops, but the larger trees and shrubs naturally grow in the valleys and on the north slopes.  This is because of the extra moisture in those areas.

Many of the wildflowers were just starting to come out, with the California Poppies (Eschscholzia californica) a noticeable accent in the steeper, more bare spots.  The Poppies in my yard grow so fast they start to choke out other plants, but it looks like they can’t out-compete the denser growths of weedy annual grasses in this environment.


Blue-eyed Grass (Sisyrinchium bellum) was noticeable among the other grasses providing a nice blue accent, along with the interestingly named Ithuriel’s Spear (Tritelea laxa), and the non-native weed Redstem Stork’s Bill (Erodium cicutarium) with its tiny lavender flowers.


This park not only has great hills to hike but also excellent views of the north bay, especially looking towards the Carquinez Strait and the city of Vallejo.   Definitely worth a visit in the spring, as long as you are sure the trails have dried out and you don’t mind dodging the cow patties!



Posted in Plants | Comments Off

45. Rhyne designs’ 3rd Anniversary

It’s time to look back on 2015, Rhyne designs’ third official year in business. The year ended with some good rainfall here, a hopeful step towards getting over the drought, but still a ways to go. The dry weather earlier in the year meant that construction work went quickly on several Rhyne designs projects with great results. Also, quite a few projects moved through the design process in 2015, making it a very exciting and busy year!

Built Work
Most exciting was the completion of landscape construction for three different properties in the Napa Valley, the culmination of years of design work, permitting, and construction coordination. In July I was thrilled to see the landscape for a 4 acre Wine Country Estate near Yountville finish up. Personal on-site placement of hundreds of plants for installation was a rewarding experience that allowed for some key fine-tuning of the design as it all came together. In October the landscape for a St. Helena Residence was installed just in time for the rainy weather. The landscape for a one-acre North Napa Residence was about 95% complete by mid-November, but the rains slowed things down after that. Likewise a landscape remodeling project in Moraga got underway in the fall and came close to finishing up before things got too soggy. I look forward to seeing all of these gardens in a few months after the winter rains and spring warmth have allowed the plants to grow and flower!

Designs In Progress
On the drawing boards in 2015 are several exciting projects that will start construction this summer. In the East Bay I have been working with a nice family to design a new landscape for their steep hillside house in Kensington. This older house has a front door that sits about 20 feet higher than street level, and the original connecting stairways have crumbled to the point of being a hazard. Working through many design options and keeping a close eye on the budget, we have come up with a pleasant sequence of stairways and terraces that lead up to the front door, tied into the existing architectural style with paving materials, railing designs, and lighting.


In Marin County, I have had the pleasure of working with another nice family on their hillside property in Belvedere, which has amazing views of the Bay. This has involved working to create a well-defined entry route up to the front door, a challenge because it is on the back side of the house at the second floor level. We looked at various design alternatives for different pieces of the project, working within a minimalist modern style to complement the house. Also in this design is a habitat garden, an outdoor terrace, an expansion of the existing lawn, and a sport court.  All are carefully arranged on this steep site to allow for all kinds of outdoor living. This project goes before the local Planning Commission soon and then on to construction.

Under construction right now is a major Rhyne designs project consisting of three residences set in a 9 acre vineyard in the Napa Valley. The house construction has moved along quickly, and landscape installation on the first house should begin in a couple of months. As the form of the first house has taken shape Rhyne designs has continued to work with the clients to fine tune the landscape design to fit with their vision of a garden full of spaces for outdoor living in an elegant modern style. I am very excited to see this one become a reality.




Updated Web Site
Rhyne designs business has increased and I have learned much in the last three years and the web site has been updated to reflect that. More projects have been added, with more photos of built work. The core information on Rhyne designs has also been updated, with clearer and simpler writing in the About, Approach, and Services pages.

Off and Running in 2016
With all the work that came up in 2015, I wrapped up my last outside consulting jobs by mid-year. This has allowed me to take on more work of my own, and stay focused on delivering quality designs to my clients. 2016 has started out at a good pace and I’m looking forward to more fun design work and seeing more drought tolerant garden designs come to life!

Posted in Design | Comments Off

44. The Native Meadow Experiment – Fall in a Drought

It has been almost 4 years since I started my so-called Meadow Experiment, tearing out my back yard lawn and replacing it with native grasses and other grassland plants, testing out all the recommended steps along the way to get firsthand knowledge of what works best. The main planting happened almost 3 years ago in February 2013, with additional plants added that November. These plants got supplemental water for the first few years, but this summer I have stopped watering entirely. I have heard from multiple sources that native plants should be established enough after 1 to 2 years that they no longer need irrigation, they can live off the winter rains. But I wanted to see how true this is, how they would survive a severe drought year without water.

Ornamental Dormancy
I think the results of this won’t be too surprising: many of the plants have gone dormant, turning brown and dying back. In the case of many of the grasses, this is a normal occurrence each year, and the brown seed heads are actually quite nice looking. Other plants have remained green but grown slower, and a few are probably not going to make it.

The Grasses
I think the grasses in my meadow will mostly survive this dry summer. Cool season grasses typically have late-summer dormancy, turning brown and essentially going to sleep until brought back to life by the winter (cool season) rains. As I’ve mentioned before, the normal maintenance for these grasses is to cut them back in the fall to make way for new growth, and I’ll be doing that in the next few weeks. So I have confidence that my various Festuca and Calamagrostis grasses will sprout new growth here in a few months with only a few losses.

Buckwheat and Iris
It has been interesting to me to watch the native Buckwheat’s behavior this summer, it’s a plant I don’t know that well. They have done fine without water this summer and put on a nice flower display and still have green leaves at this point. The hybridized native Buckwheat (Eriogonum grande var. Rubescens) has done better than the locally native one (Eriogonum nudum auriculatum).  Definitely a plant type I am going to start using more in my garden designs. The Irises (Iris douglasiana) are the other plant that still has plenty of green foliage which is a little surprising to me because you see Irises on the coastal bluffs of Northern California that turn mostly brown this time of year. I guess being a little inland and probably a different soil type has made a difference.

Yarrow and Poppy
The Yarrow plants (Achillea millefolium and A. millefolium rubra ‘Rosy Red’) have been interesting with mixed reactions to the drought depending on the plant. Some went completely dormant by mid-summer while others had a new spurt of growth in August and September with smaller leaves and shorter flower stalks.

The California Poppies (Eschscholzia californica) have also had a second wind this summer with smaller and sparser growth that wasn’t all that attractive, but I did get a few flowers. Both of these plants die back and turn almost black which calls out to me to be cut back and cleaned up, but I tried to leave the seed heads out on the ground for the birds. And not to leave out the Blue-Eyed Grass (Sisyrinchium bellum) and Sea Thrift (Armeria maritima) plants, but they are more typical perennials that consistently die back in the late summer.

Winter Refresh?
Now we enter the “rainy season” which technically started on October 15 in the Bay Area, but the last few years it has hardly rained at all before January. Soon I will start cutting things back, removing dead flower heads and foliage but keeping the core of each plan intact. Hopefully some rain will come in November and December and all my meadow natives will sprout new growth. If not I’ll be filling in some spots with new plantings. As always it will be interesting to see how things evolve!

Handouts and Notes from my attendance at the California Native Grass Association’s workshop: Using California Native Grasses in the Water-Conserving Landscape www.cnga.org



Posted in Experimenting | Comments Off

43. Sustainable Materials (part two)

We are talking again about sustainable landscape materials, another one of those big topics that gets bigger the more I learn about it.  I previously covered some key points on the best types of materials to use, now I want to dig deeper into some issues related to potential toxics in some landscape materials and then focus a bit more on wood and its alternatives.

Toxicity in Landscape Materials
Gardens are generally great things for the environment compared to parking lots, buildings or factories, but there are a few materials commonly used in landscapes that have toxic properties.  These properties include hazards to construction workers during installation, as well as unhealthy chemical emissions over time after things are installed.

An obvious example is the chemicals used to control weeds and pests (herbicides and pesticides).  I have written before about herbicides and won’t get into the specifics here, but in general these types of products should be avoided.  Use alternative natural methods where possible, and when they are necessary hire a professional with proper training and equipment to apply them.  Beyond that, there are a several commonly used materials that do have some potential toxic environmental effects that I want to discuss.

PVC (Poly Vinyl Chloride) is one of the more toxic landscape materials and is the main plastic used in the irrigation and drainage piping needed for almost every garden project.  PVC has negative environmental effects throughout its life cycle – in manufacture, installation, use, and disposal.  It has a high level of chlorine in it, which releases very toxic (carcinogenic) dioxins when manufactured.  Once installed, PVC will off-gas unhealthy chemicals that are especially dangerous in enclosed spaces.  With irrigation piping that is not such a big issue but over time PVC does emit toxic chemicals into the soil that will contaminate the groundwater.  Disposing of it is a big issue as well, it is not recyclable and again gives off toxic dioxin if burned.  I’m not very expert in the chemistry or other details of this issue, but see the references below for more detailed information.  Suffice it to say that we should be limiting the use of PVC as much as possible.  Unfortunately there is no good alternative for irrigation piping that I’m aware of.  Copper is of course a good irrigation piping material, but quite a bit more expensive, energy and resource intensive, and not without its own contamination problems.

Paints and Coatings
There are many different kinds of paints, stains, sealers, glues, etc. used in landscape construction and quite a few have negative environmental effects.  A common issue is the off-gassing of volatile organic compounds (VOC’s) that are toxic when inhaled and have serious long term health effects.  These VOC’s also contribute to general air pollution.  It is true that most landscape paints and coatings are applied to surfaces outdoors where there is plenty of ventilation to mitigate immediate health effects, but it is still a good idea to seek out “low VOC” paints and stains for the health of those doing the painting and for overall air quality.

Treated Wood
Wood that can resist rot, fungus and insects is essential in landscape construction, things like fence posts and vegetable beds need a wood that can be in contact with wet soil and not rot away in a few years.  Old growth heartwood from Redwood trees and other species meets this requirement, but gone are the days when that was plentiful.  Therefore chemically treated wood is, as far as I can see, a necessary evil in the landscape.  The options for treated wood have gotten better in the last few decades as we have moved away from using things like chromium and arsenic.  However, it is still a confusing marketplace of different products and limited environmental information and I can’t say I found a clearly superior option in terms of sustainability.

One type of treated wood, CCA (chromated copper arsenic) is clearly bad for the environment, with likely leaching of these highly toxic chemicals into the soil over time.  My understanding is that CCA has been phased out for residential uses at this point in California.  The Wolmanized brand, stocked commonly at big box home improvement stores, seems to be a more benign product; their residential treated wood uses Copper Azole, without the chromium or arsenic.  It still comes with warnings on skin contact, inhalation of sawdust, potential leaching into the soil, and burning, so I’m not sure it is a huge improvement.  It is also regulated in California as a hazardous material, it can only be disposed of in special waste facilities.  Because of this, it is important to only use treated wood when absolutely necessary, perhaps turning to plastic lumber for some of your landscape construction.

Plastic lumber
When compared to wood, plastic lumber it is at least as durable and it doesn’t get eaten by insects or rot when in contact with soil.  Many plastic lumber products are made from recycled plastic, and some are recyclable themselves.  But not all types of plastic lumber are the same, and some do in fact contain PVC or other plastics which have the toxicity issues mentioned above.   Others include a mix of ingredients such as wood fiber or fiberglass that make them more hazardous to work with and difficult to recycle.

The best plastic lumber products in terms of general sustainability are those with high post-consumer recycled plastic content (at least 50%), and a single plastic ingredient, typically polyethylene.  Polyethylene is thought to be a less toxic plastic, and it is one of the most recycled plastics, found in things like milk jugs and detergent bottles.  However, this type of plastic does not typically work well for structural uses like beams and posts – fiberglass and other materials are often mixed in to give the plastic lumber more strength.

I won’t get into specifics on different plastic lumber products but there are a wide range of options and it is important to look behind the “green” claims of the different companies to be sure the product is truly a positive for the environment.  Plastic lumber has come a long way from the early versions of the material that faded and warped, but take a close look at what it is made of and how easily it is to work with.  Trex, one of the most well-known plastic lumbers consists mostly of a wood plastic mix, with a coating of a different plastic.  It does have high recycled content and a nice finished look, but doesn’t actually recycle all that much plastic.  Eco-Tech is a lesser known company, but they manufacture lumber that is 100% polyethylene from post-consumer sources.  Neither of these products is useful for structural applications, so we are still stuck with a less environmentally friendly option in those cases.

Wood – the bad and the good
Wood is the traditional material for some of the most common landscape structures are fences, decks and trellises.  We are now in an era where high quality wood that can last in contact with the ground is often expensive and/or coming from an environmentally questionable source.  Chemically treated wood and plastic lumber are able to replace wood in some cases, but they do have their disadvantages.

Ultimately wood is a renewable resource that will provide more supply over time, especially compared to the petroleum based products that go into plastics.  But our consumption of wood is much faster than the growth of Redwood forests can sustain, and the environmental damage of large scale clear-cutting is well known.  There are some responsible timber operations out there as well as independent certifiers of sustainably harvested wood such as the Forest Stewardship Council that can help inform wood choices.  Bamboo is a much faster growing plant that can be used to build some interesting structures, but is not yet very widely adapted to US building techniques.

In my opinion wood is still a great material to use, it just has to be used wisely.  A good sustainable designer should use high quality wood like old growth Redwood only for special situations where it can be appreciated.  Good design can also work with the known dimensions of wood to limit the amount of waste produced, for example adding a few inches here or there so that the standard 8 foot board doesn’t have to be cut.  Otherwise seek to use alternative materials with high recycled content and limited toxicity and save some of that wood for the next project!

Bay Friendly Gardening Guide and Landscaping Guidelines https://www.bayfriendlycoalition.org/publications.shtml

Bay Friendly Landscaping Guide to Recycled-Content and Salvaged Materials https://www.bayfriendlycoalition.org/publications.shtml

Sustainable Landscape Construction, by J. William Thompson and Kim Sorvig

PVC information resources:



Blue Vinyl – an award winning documentary about PVC and the environment, released in 2002

Treated Wood information resources:


Plastic Lumber information resources:
The Healthy Building Network’s Guide to Plastic Lumber, June 2005:

Trex information on eco-friendly processes:

Eco-Tech information:

Posted in Sustainability | Comments Off

42. Sustainable Materials (part one)

Continuing my series on various aspects of landscape sustainability, I’d like to get into the subject of sustainable landscape building materials.  Landscape construction uses a wide range of materials, including natural things like plantings and soil.  However in this case I am talking about manufactured materials such as stone, concrete, tiles, irrigation piping, lumber, and so on. 

Your choice of landscape materials effects the environment in many ways, but generally you are looking for materials that conserve natural resources, reduce energy use, reduce greenhouse gas emissions, don’t contain toxic substances, and/or keep waste out of the landfill.  With so many aspects to this subject, it is good to begin evaluating a material in terms of two general concepts: embodied energy and life cycle analysis.

Embodied Energy
A major part of sustainable materials is reducing energy use, especially non-renewable fossil fuels that contribute substantially to global warming.  Embodied energy is the sum of all the energy used to create the material and get it to the building site, including raw materials extraction, manufacture, and transportation.  A deck board may not take much energy to get from the lumber yard to the site, but if it came from a rainforest in Brazil it has a much higher embodied energy because of the transportation involved.  Although we won’t get into the details here, the calculation of embodied energy for various materials is an evolving science with great promise for making informed choices, and it is a useful concept to keep in mind.

Life Cycle Analysis
It is also important to consider the environmental impacts of a material throughout its “life cycle”.  This is often called the “cradle to cradle” view where you consider everything from how the raw materials are extracted to the ability to recycle or re-use a material at the end of its current ‘life’.  A clay brick may take a lot of energy to create, but if installed in the landscape without mortar it is completely salvageable for reuse again and again for many years, making it highly sustainable.  Again, we can’t get too much into this complex topic, but it does help us to think about how a material is or is not sustainable.

Based on these concepts, there emerge three main categories of sustainable materials that are best at minimizing environmental impacts:  locally produced items, salvaged materials, and those with recycled content.

Local Materials
In an ideal situation, the structures and paving of a landscape would consist of materials taken directly from the project site – trees cut down would be milled into lumber, rocks would become stone pavings, and clay soils would be turned into adobe walls.  This not only eliminates the considerable environmental cost of transporting heavy building materials, it gives the design a pleasing uniqueness tied to its location.  A beautiful example that I have seen is the incorporation of site soils into building walls using a technique called rammed earth.  There are also a variety of mixes that combine site soil with concrete and other binders that have promising landscape uses.

More commonly the materials are transported to the site, requiring the use of gas-guzzling, polluting trucks, but you can still seek out relatively local materials to minimize this impact.  Often the heavier landscape materials such as stone, gravel, concrete and sand are already mined/manufactured locally to keep transportation expenses low.  However in our modern world of cheap global container shipping, many things such as finish stone materials come from other countries.  These materials are made cheaper than local stone in part because of a lack of environmental regulations and cheap, exploitative labor – definitely not sustainable.

I often curse at the lack of information on exact sources for many landscape materials, especially things like river rock and decorative gravel. I am hopeful that people will increasingly question the sources of those materials and pressure suppliers to make that information available.

Salvaged Materials
Salvaged materials are things that you save from going to the landfill, but don’t require any manufacturing to make them useable.  These materials fall into two rough categories: commonly used materials and unique items.  Unique items can be almost anything that you can find; your creativity is the only limit to how they can be used in the landscape.  To find unique items takes some time, creativity and even luck.  I think that the best way to put it is “let the materials inspire the design.”  One beautiful example is incorporating colorful glass bottles into an adobe or concrete-like wall.

Commonly salvaged materials include stone pavers, concrete, brick, lumber, metalwork, tiles, tires and many others.  Using reclaimed wood lumber from old buildings has become quite the trend lately, showing up as a finish material in bars and restaurants all over the Bay Area.  Its use is ubiquitous enough to make me wonder how much of the reclaimed wood is truly a waste product being re-used.  Of course if you are using it for your own project, be sure to get documentation of the source.

One good common material that can be re-used is concrete.  When you have a concrete slab or sidewalk that is going to be removed, you can break it up into pieces commonly called “Urbanite” for re-use.  It can be stacked into low walls or laid in a gravel area as stepping stone paving.  One thing I learned in doing my own small urbanite wall was that not all concrete sidewalk pieces have a uniform thickness, this can make it harder to create nice brick-like rows for a wall.

With urbanite and all salvaged materials it is especially important to carefully design their installation to make them lasting pieces.  It is also critical that you use an expert installer for construction, someone with experience working with your specific salvaged materials.  Don’t forget that these materials have already had years of wear and tear and if you don’t fit them into your new garden appropriately they won’t last very long.

Recycled Content Materials
Recycled content materials are those that are manufactured using waste products.   This isn’t guaranteed to have a net positive overall benefit, but is generally better than putting trash in landfills.  One question to ask of recycled materials is the transportation and manufacturing energy that goes into converting a waste product into something useful – it can be energy intensive.  But there are many great recycled materials for use in the landscape including asphalt and crushed concrete, yard waste, plastic, rubber, glass, paint and many others.

Here in the Bay Area we have pretty established systems for collecting and recycling yard waste into mulch and compost.  Curbside pickup in many cities collects yard and kitchen waste and takes it to centralized facilities where it is composted into soil.  In my neighborhood the garbage company actually holds regular events where it gives away bags of this composted waste that is ready to go back into the garden as a soil amendment.  City landscape maintenance staff as well as private tree companies often offer chipped tree trimmings for free to use as bark mulch.  Just be careful of the source, there is some risk of plant diseases contained in the chips, and some that are heavy in Eucalyptus or Pine chips may alter your soil chemistry negatively.

Tumbled glass and ceramic bits are one of my favorite recycled materials, with great design potential.  Crushed glass bottles and tiles are tumbled to remove the sharp edges, they start to resemble the “beach glass” you may have seen while beachcombing.  I have experimented with the use of tumbled glass in the landscape and it does have its limits – it is fairly expensive so you don’t want to use it over larger areas, it is better as a filler for gaps between paving or as a mulch in pots.  It also does lose its brightness over time, especially when set at ground level where it easily collects dust and other debris, so keep that in mind.

Materials Matter
You can start to see how your materials choices matter to the environment. As the Bay Friendly Landscape Guide says: “use materials for the highest use – avoid ‘down-cycling’.”  In terms of embodied energy the best materials are locally made, are salvaged from the waste stream, or at least have recycled content.  There are, however, other considerations for the overall sustainability of materials, such as potential toxins they release into the environment, or how renewable their raw materials are.  We will get into these and other topics in Part Two, to follow soon.

The ongoing challenge with sustainable materials is finding consistently good ones that perform as well as the mainstream materials.  Many innovative materials have great promise but still lack the testing and proof of long term durability.  Unfortunately this is enough to deter their use by the construction industry because any failure leads to angry clients and expensive replacements. I am hopeful that good research on sustainable materials will continue, and that the total environmental cost of building materials will become clearer so that conscious consumers like you can make better decisions.
Bay Friendly Gardening Guide and Landscaping Guidelines https://www.bayfriendlycoalition.org/publications.shtml

Bay Friendly Landscaping Guide to Recycled-Content and Salvaged Materials https://www.bayfriendlycoalition.org/publications.shtml

Sustainable Landscape Construction, by J. William Thompson and Kim Sorvig

A sampling of Salvaged Materials Suppliers:
Urban Ore (Berkeley)  http://urbanore.com/

Building Resource & Red Shovel Glass Co.:  (San Francisco) http://www.buildingresources.org/index.html

Artefact Design and Salvage (Sonoma) http://www.artefactdesignsalvage.com/

Green Waste Recycle Yard (Richmond)

Driftwood Whole House Salvage (Peninsula)

California Materials Exchange CalMAX

California State Recycle Store:  searchable listing of companies making products from recycled materials

Posted in Sustainability | Comments Off

41. Walk-on Lawn Substitutes

Even in times of normal rainfall, I try to discourage residential lawns unless someone really needs a backyard play space for their kids.  With California’s severe drought, its time to consider replacing any lawn areas in your garden.  There are many ways to replace that thirsty, chemically dependent, monocultural lawn.  These include a native meadow, other Mediterranean climate shrubs, or permeable pavings like crushed stone.  However, it is a little harder is to find a drought tolerant substitute for a lawn that can take the same kind of uses.  Especially difficult is finding a non-grass plant that has such a uniform texture for activities like soccer and croquet.  Fortunately there are a few good options out there.  Some are simply other grass types that can use less water, while others are low-growing plants that don’t mind foot traffic.  If the foot traffic is very light, or you can add some stepping stones, the options expand to a longer list.  You will also see in local nurseries a few low mat-forming plants that are walkable, but some use as much water as a traditional lawn.

Five Plants to Consider
Based on my experience and research I’ve picked five plants to look at in more detail as good walk-on lawn substitutes for Northern California gardens:

1. UC Verde Buffalograss
(Buchloe dactyloides ‘UC Verde’)
This species of grass is native to central North American prairies.  The UC Verde is a selected variety that grows better in California, although not as good on the immediate coast.  This grass is a little slow to fill in but eventually spreads by runners to form a uniform lawn.  It naturally grows to about 4” tall with minimal water, but added irrigation will cause it to grow taller.  Once this grass is established (usually about a 2 year process) it becomes a nice lawn that needs about 20% to 40% less water than traditional turf.  Besides the somewhat long establishment period, its other disadvantage is winter dormancy:  it turns brown in the late fall, still covering the ground but not as nice looking.  It greens back up with new growth in the early spring.  There are some excellent resources online that provide all the details on installing and maintaining this type of grass lawn, see the References below.

2. Dune Sedge / Meadow Sedge
(Carex pansa)
This is a fairly well-known lawn substitute, along with a few other members of the Carex genus such as Carex praegracilis.  A California native plant, this Sedge is grass-like, but a little more coarse in texture than lawn grasses.  It tends to grow higher than most lawn grasses, but with regular mowing it can have a pretty uniform texture.  This grass is considered a moderate water user, but still uses less than a traditional lawn in most situations.  One article reports that this grass uses 50%-70% less water than the typical Los Angeles lawn (see article reference below).  Meadow Sedge is great choice for those that definitely need a walkable lawn but want to save some water.

3. Dymondia / Silver Carpet
(Dymondia margarete)
This plant has wider leaf blades than a lawn grass but still grows low and forms a fairly uniform carpet.  Native to South Africa, this plant has a nice grey-green and silver foliage and occasional yellow flowers.  Once established it needs little water, however with too little water the texture will change, with the leaves curling up a little bit.  It can only take light foot traffic, so it is not suitable as a replacement for a lawn that gets heavy use.

4. Beach Strawberry
(Fragaria chiloensis)
Although not similar in appearance to a lawn, the Beach Strawberry is an excellent California native alternative.  It is related to the commercial edible strawberry, but its fruit production is less prolific, with smaller, bitter berries. It has some white flowers in the spring, and the leaves can take on a nice reddish color in the fall.  Although it forms a fairly even carpet that can be kept uniform by mowing, it is a little lumpy for some lawn play activities like croquet.  It can do well in partial shade, but may not form as much of an even carpet in shadier spots.

5. Creeping Thyme
(Thymus praecox arcticus)
There are several good varieties of this low growing Thyme, all of which have low water needs and fragrant leaves.  It spreads quickly and easily as long as the soil has good drainage and it isn’t overwatered.  It is covered with pretty small lavender flowers in the spring & summer, however they can attract a lot of bees.  The variety ‘Elfin’ is smaller leaved than most and has only a few flowers, so that helps with any bee issues.  Like the Dymondia, Creeping Thymes also tolerate only light foot traffic.

Other Planting Options
Below is a more comprehensive list of alternative plantings, including several good options that will still have a low uniform look but aren’t walkable.  In a garden it is always nice to have low open areas to keep the design from getting too busy and cluttered, so plants like the Groundcover Manzanita and Stonecrop are great ones for those situations.

I’ve also included on the list some common low groundcovers like Blue Star Creeper that can take the place of a lawn but won’t help you conserve water.  Normally I would not recommend these, but they could have a place in certain small areas.  They do have one advantage over lawn, they provide a more interesting looking ‘carpet’ that can include seasonal flowers.  They also tend to require less fertilizer and herbicides, and probably provide more habitat value than a traditional lawn.


Artificial Turf
Artificial turf is another option when looking for water-saving ways to replace a lawn while still providing a good space for recreation.  Its high installation cost is generally offset after a few years by savings in watering, fertilization and other maintenance.  You will still need to occasionally hose artificial turf down to keep it clean, and also on hot days – it can get hot to the touch.   The fact that it is artificial does mean it has no value as habitat and doesn’t provide any of the other benefits that living plants do.  The pros and cons of artificial turf is a larger discussion that I will follow up on later.

Hopefully this inspires you to get rid of that lawn and make a significant impact on your garden’s water use while creating a more interesting looking space!

Reimagining The California Lawn, Water Conserving Plants, Practices, and Design, a book by Carol Bornstein, David Fross and Bart O’Brien

Master Gardeners of San Francisco – web article “Lawn Alternatives – Ground Cover Trial”  interesting study of 3 lawn substitutes for coastal northern CA:  http://smsf-mastergardeners.ucanr.org/Elkus/ground_cover/

California Native Plant Society – web article “Alternative to Lawns”  by Deva Luna  http://www.cnps.org/cnps/grownative/tips/lawn_alternatives.php

Steppables – a supplier of low-growing “steppable” plants:  http://www.stepables.com/

UC Verde Buffalograss Links:      http://ucverdebuffalograss.com/     http://ccuh.ucdavis.edu/industry/ucverde

John Greenlee Associates has great information and photos on many grasses:  http://www.greenleeandassociates.com/plant-gallery.html

The Lowdown on Dymondia and Three Other Lawn Alternatives, article in the LA Times, January 23, 2013 http://articles.latimes.com/2013/jan/23/news/la-lh-dymondia-and-three-other-lawn-alternatives-20130123

Bay Friendly Gardening Guide and Landscaping Guidelines http://www.stopwaste.org/home/index.asp?page=8


Posted in Plants | Comments Off