The Loma Prietan - July/August 2009

Gardening Green

Gardening by Plant Community

story and photo by Arvind Kumar

The Seabluff Section of the East Bay Regional Parks Botanic Garden contains plants such as rock cress, live forever, and polypody fern.
The Seabluff Section of the East Bay Regional Parks Botanic Garden contains plants such as rock cress, live forever, and polypody fern.

Since 1960, the US Department of Agriculture has published hardiness zone maps to help gardeners determine which plants will survive in their location. For Western states, Sunset Magazine defined a more precise zoning system based on winter lows as well as summer highs, soil types, length of growing season, humidity, and rainfall.

For the environmentally conscious gardener who wants his or her space to be more in tune with its natural surroundings, there is another way to view the garden: by plant community.

Botanists and ecologists tell us that in nature plants don't occur in isolation from each other. They are found in rather predictable groups or associations called plant communities. Plants from a given community — from annuals and forbs to shrubs and trees — have evolved under the same conditions of soil, climate, slope, and exposure.

The notion of creating gardens based on plant communities is becoming popular among environmentally minded landscape designers and homeowners. Gardening by plant communities provides you with a palette — nature's palette — of plants to choose from. Caring for plants in the same plant community is easier because their needs are similar.

Botanist Philip Munz defined 11 plant communities covering all of California:

1. Coastal Strand
2. Salt Marsh
3. Freshwater Marsh
4. Coastal Scrub
5. Coniferous Forest
6. Mixed Evergreen Forest
7. Woodland-Savanna
8. Chaparral
9. Grassland
10. Alpine Fell-Field
11. Desert Woodland

No matter where you live in the state, your garden naturally belongs to one of these plant communities. Just as you would want to know your USDA and Sunset zones, you also want to know what your plant community is.

Find Your Plant Community

So how do you find your plant community? You can consult Munz's A California Flora, or the weighty Jepson Manual. For most of us, it is sufficient to look it up on the Las Pilitas Nursery website at www.laspilitas.com: click on the Nature of California menu, then California Plant Communities. From there, you can look up your plant community by zip code or city name.

As an example, according to Las Pilitas, my home in San Jose lies at the intersection of two plant communities: Central Oak Woodland, and Coastal Sage Scrub.

Typical oak woodland plants include valley oak (Quercus lobata) and coast live oak (Quercus agrifolia), and shrubs such as toyon (Heteromeles arbutifolia), coffeeberry (Rhamus californica) , currant/gooseberry (Ribes sp), and manzanita (Arctostaphylos sp).

Common plants of the coastal sage scrub are California sagebrush (Artemisia californica), California buckwheat (Eriogonum fasciculatum), California lilac (Ceanothus sp), sticky monkey flower (Mimulus aurantiacus), sage (Salvia sp), and coyote brush (Baccharis pilularis).

I can vouch for the accuracy of this data: all the plants named above are doing very well in my garden!

Another useful website, www.calflora.org, allows you to look up plants by name, by county, or by plant community. Its "What Grows Here" link lets you query reported occurrences of native plants growing near your town, zip code, county, or park.

One caveat is that your garden, surrounded by fencing, concrete, and stucco, is no longer a pristine natural environment. Each microclimate in your yard — the bed by the south-facing fence, hot and dry due to reflected heat, or the bed next to the house that is shaded all year long — may deserve its own plant community, different from the dominant one for your region.

Sierra Club life member and California Native Plant Society director Arvind Kumar grows native plants in his Evergreen garden. He can be reached at chhaprahiya@yahoo.com.