Using Non-potable Water on Native Plants

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Yesterday I attended an all-day conservation forum given by the County of Los Angeles Department of Parks and Recreation called Recycled Water/Plant/Soil Compatibility. There were two talks on the effects of recycled water on soil and plants, and these were pretty technical. Not surprisingly, Debbie Evans from Tree of Life Nursery reported that recycled water is probably not appropriate for use in a commercial nursery. Carol Bornstein gave the talk that I think many people were eager to hear: Native and Drought Tolerant Plants Suitable for Use with Recycled Water.

In preparation for her talk, Carol visited a number of parks in the Santa Barbara area that used recycled water on drought-tolerant plants. She then compiled a list and showed pictures. She was clear that the resulting list is not: the best list, the only list, or even an appropriate list of plants that would work well with recycled water. She pointed out that the idea behind using native and drought-tolerant plants is to reduce the irrigation needed for their success. A better strategy, therefore, might be to use potable water during the occasional years when there is little winter rain. One might even accept the losses that occur during dry years so that over time only plants that can survive and look good in our climate will be part of the parks.

Carol was clear that the plants on her list was based on a small number of parks in the Santa Barbara area, and many of these plants would not be successful in hotter, drier inland areas. She also pointed out that there is no good research comparing how plants perform when watered with potable versus recycled or greywater. Controlled experiments on this would provide very useful and interesting information.

The list was comprised of the fairly typical native plants that one finds in gardens and parks. It was interesting to see how Carol determined which plants she thought would be good candidates for poor water. They were usually coastal plants that receive salt spray or are found in salt marshes, and therefore are tolerant of higher salt levels.

I’d like to pursue this further and want to ask if there are any native plant gardeners who have tried this: growing native plants using greywater water. (I don’t think anyone has access to recycled water for residential landscaping yet.)

Even without field data, ancedotal or otherwise, on native plants and recycled or grey water, it would be helpful to have a list of plants that are more likely to be tolerant of poor water.
Criteria, as suggested above, could include plants found in: coastal areas with salt spray, salt marshes, and heavy soil with poor drainage, especially desert washes where salts and minerals from the soil cannot leach out. I’d also include plants that seem to be tolerate of a very wide range of soils.

Finally, before giving my first stab at this list, Jane Tsong emailed me with information on greywater use in her garden:

For the record, last summer, like a boor, I watered newly planted Encelia californica, mahonias, mimulus, heuchera, eriogonum giganteum, penstemon and salvia apiana among other things with greywater that had traces of soap/shampoo in it. Although all survived but the penstemon, the salvia has never taken off, and I this summer when I used clean water from the hose, all the plants seemed a LOT happier.

As for the list, so far I have come up with the following (please excuse the use of botanical names only, once there is a more complete list I’ll add common names):

Achillea millefolium
Argemone corymbosa

Aster chilensis
Baccharis pilularis
Baccharis salisifolia
Biden laevis
Carex praegracilis
Ceanothus maritimus
(and others found at the coast)
Chilopsis linearis
xChitalpa tashkentensis
Erigeron chilensis
and cultivars
Eriogonum arborescens
E. cinereum
E. latifolium
E. parvifolium
Eriophyllum nevinii
Fragaria chiloensis
Juniperus california
Justicia californica
Myrica californica
Prunus ilicifolia
ssp. lyonii
Rhus integrifolia
Shepherdia argentea
Stanleya pinnata
Washingtonia filifera

Any other thoughts?

10 thoughts on “Using Non-potable Water on Native Plants

  1. Barbara, are you acquainted with the City of Santa Monica Office of Sustainability and the Environment? If not, here is a link to contact info on their site:<br />Scroll down for the Urban Runoff, Water Efficiency and Landscape folks. (May be best to start with Russell Ackerman.) Santa Monica has a water reclamation

  2. Oh, and thanks for sharing the info. Very interesting, timely topic given the new graywater regulations, and my prediction, worsening of our water situation! Score: one point for adaptable natives and zero for H2O-guzzling lawns!

  3. My experience with graywater and natives is limited to this summer and hasn&#39;t been anything approaching a scientific survey. All the plants survived with the exception of Baja native Verbena lilacina. Galvezia speciosa (both the type form and the &#39;Firecracker&#39; strain) seemed to not mind it much. Less-than-year-old plants of Encelia californica, Solanum parryi and S. xanti, Salvia

  4. Janis, I am familiar with the Santa Monica Office and their wonderful Garden/Garden program. I haven&#39;t spoken with them in quite a while so thanks for reminding me about them. I will give Russ Ackerman a call.<br /><br />James, I&#39;m surprised that such young plants took the greywater so well. I understand that you didn&#39;t do a comparison. Did the water come from the shower drain?

  5. Western Spicebush and Yerba Buena both get water from our washing machine. They&#39;ve done great.

  6. Ryan, how old were the plants when they started getting greywater and how long have they been getting it? Final question, what is your soil drainage like? These surprise me a little. Both has fairly thin leaves and are adapted to more woodsy locations – presumably with more acidic soil. I think we are just going to have to test every plant!<br /><br />Thanks for the info.

  7. I wasn&#39;t sure how the yerba buena would do, too, but it&#39;s quite happy. It was planted as a 4&quot; three years ago in an open bottomed container filled with potting soil. The container is in the dripline of the calycanthus. It&#39;s a rootbound 5 gallon planted 2 years ago, now about 8 feet tall. It&#39;s the Bay Area champion for clay soil, poor drainage, and general tolerance of

  8. Thanks for the info, Ryan. I definitely agree that plants that tolerant clay soil probably have a better chance with recycled water. <br /><br />Mary Delle, I will be updating the list and posting the updates. If I haven&#39;t done it yet I will make a tag for recycled water.

  9. Mary Delle

    Really interesting post on a subject that&#39;s really on the cutting edge of gardening. Keep us posted on your findings.

  10. Barbara,<br /><br />I&#39;m glad to have found this list. I&#39;m working with the City of Long Beach Office of Sustainability ( where I co-lead simple greywater installations for 36 residents. A few residents have requested a native plant palette and this list is a perfect start. At the moment, I&#39;m developing design guidelines to water California natives utilizing a

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