Watering Strategies from South Bay Botanic Garden

by Susan Krzywicki

Eddie Munguia, Horticultural Lab Technician South Bay Botanic Garden

Eddie Munguia, Horticultural Lab Technician South Bay Botanic Garden – Photo by Susan Krzywicki

After so much debate about how to water native plant gardens, you’d think it had all been said. Let me add some tips and techniques from Eddie Munguia, who is the Horticultural Lab Technician at the South Bay Botanic Garden, located on the campus of Southwestern College in Chula Vista. Eddie installed a native garden over four years ago and one of the key objectives of the botanic garden is to do just this sort of closely observed research and analysis.

Split Cycle Watering – preventing root zone waterlogging
Last July, after attending a professional workshop, Eddie decided to experiment with split cycling – taking the duration of watering proposed, and dividing it into two segments with a two hour gap in between. For example, instead of running a sprinkler zone for 10 minutes, he runs the zone for 5 minutes, in the early morning hours. This allows for absorption by the soil, while avoiding swamping the plant, which can lead to disease and plant death. Eddie has decided that his clear mandate is to “imitate rainfall” by providing supplemental irrigation that looks more like our natural pattern: gentle, sparse summer rains, not heavy storms. During Santa Anas, he recommends 2 minute spritz to cool the plants off. If the plant is suffering from summer stress, he doesn’t dump a lot of water on it, he just refreshes it.

The garden, which is well over 5,000 square feet, is mostly Diablo clay with native hybrid species originating in San Diego county and the Channel Islands.

A view of South Bay Botanic Garden

A view of South Bay Botanic Garden – Photo by Susan Krzywicki

Results: longer bloom times, good growth
Within two weeks of implementing this strategy in July, everything was flourishing. Coast sunflower (Encelia californica) now blooms two months longer. Bladderpod (Isomeris arborea) now produces flower for him all year round. Showy penstemon (Penstemon spectabilis) is blooming later in the year. Bush poppy (Dendromecon rigida) species doubled in size. The garden stay a little greener into summer. And Eddie even observed a third flowering cycle for San Miguel Island buckwheat (Eriogonum grande rubescens).

Advice: Experiment and adjust
Eddie says, “Don’t be afraid to experiment with your watering cycles. As long as you are not bogging them down, or the root zone is getting drenched, they will do OK.” He says he got lucky on the first try with his split-cycle low-impact changes. So, if you follow his method, note garden changes over at least a month, then adjust again.

Would you consider this for your native garden? Please let us know your thoughts, and, if you try this method, please do keep us up-to-date with your progress and observations.

This article was first published in the San Diego Horticultural Society October 2016 newsletter.

Susan Krzywicki is a native plant landscape designer in San Diego. She has been the first Horticulture Program Director for the California Native Plant Society, as well as chair of the San Diego Surfrider Foundation Ocean Friendly Gardens Committee, and is on the Port of San Diego BCDC for the Chula Vista Bayfront.

CNPS Takes It to the Capitol!

CNPS (1)On September 14, CNPS and partners celebrated the launch of Save Our Water’s “Fix It For Good” public education campaign by breaking ground on the Capitol landscape conversion project with a sheet mulch demonstration on the East Lawn of the Capitol. The event was put on by the California Department of General Services to showcase their commitment to rethinking the landscape on the Capitol grounds by converting lawn and other high water use areas to water-wise landscapes featuring California native plants. The goal of the demonstration is to teach the public about sheet mulching, an environmentally friendly lawn conversion technique that removes your lawn, creates a weed barrier, and fortifies your existing soil all without having to haul material off to the landfill. The demonstration was accompanied by a small water conservation expo where partner organizations hosted educational activities and information booths.

2015-09-14 22.50.15CNPS had a table set up with a beautiful array of native plants, all which were grown by the Sacramento Valley Chapter’s Elderberry Native Plant Nursery, making the table an instant hit by all passersby! People stopped to tell stories about their own landscape projects, asking for tips on gardening with California native plants and local native selections. This was an ideal opportunity to refer them to upcoming CNPS Chapter plant sales. A plethora of resources were distributed to encourage the blooming interest in native plant horticulture and excitement was rallied for the upcoming California native plant gardens.

The launch of the ‘Fix it for Good’ campaign also celebrates CNPS’s partnership with Save Our Water– California’s official statewide water conservation education program. CNPS and Save Our Water are joining forces to teach Californians about the numerous benefits of gardening with California native plants and how they play a critical role in conserving water in the landscape. CNPS developed content for their Gardening with California Native Plants page and wrote a guest blog post on CNPS’s drought resources. This partnership will allow CNPS to reach a wider audience, greatly expanding our outreach efforts on a statewide platform.

Castles and Moats for Smart Drought Irrigation

Jessica Dowell

Plant Basin-flat3

Diagram of a “Castle and Moat” plant basin by Jessica Dowell.

Have you tried dumping dish water on your plants just to watch the water flow away from the plant? If so, try using the castle and moat plant basin method. Whether watering your garden by capturing water from your kitchen sink or installing drip irrigation, good plant basins make a big difference. Basins capture water, rain or otherwise, and allow it to sink in around the plant’s roots. It is conceptually similar to mulch basins used for “Laundry-to-Landscape” grey-water systems or rain gardens. With the continuing drought it makes sense to give our plants all the tools we can to make the best of the little water available.

Example of a Castle-and-Moat plant basin on a slope by Jessica Dowell.

Example of a Castle-and-Moat plant basin on a slope by Jessica Dowell.

When working with people unused to building basins when installing plants, I like to compare the structure of the basins like a castle surrounded by a moat. The moat is then backfilled with mulch. The mulch leaves space for water to fill up and soak into the soil around the roots. Basins can take a variety of forms depending on your soils and slope. For example, if you have heavy clay soils then your plant should be set on a hill about one inch overlooking its moat above the surrounding soil. For most soils though, the plant should be set at the same elevation as the soil around it and the moat is dug 3- 12 inches from the root ball depending on the size of the plant and your soils. I like to dig my moats wider than deeper but adjust to the space available and your site. Castles and moats work for sandy soils too. In that case, the organic matter backfill ends up being the source of moisture holding. The most important thing is to avoid putting your plant at the bottom of a bowl. Even with the little water available, it can rot your plant. The same is true if your soils are poorly drained and are left to create a berm, impeding water flow.

For illustrations of this method, I like Caltran’s details for plant basins (2010 Standard Plan H3 ). They are simple and available to the public.  You can also find out more at the Arbor Day Foundation  and from Master Gardeners. In fact, here is an El Dorado Master Gardeners slide presentation  (link opens as a large pdf) on harvesting rainwater and greywater use from CNPS El Dorado Chapter president Alice Cantelow.

As always, experiment and adapt to your site and needs.

Greg Suba spotted this:

The New York Times article about our new paradigm was an interesting read.

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People are still confusing “drought-tolerant” with “native plant” and I have mixed emotions about that.  There are specific benefits to putting native plants into our gardens:

  • Heritage
  • Larval hosting
  • Soil interaction
  • Ethnobotanic connections

So, we continue to work on getting the message out. Have any ideas on how we can do that? Email me with suggestions – skrzywicki@cnps.org