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.

One thought on “Watering Strategies from South Bay Botanic Garden

  1. This is a very nice article on the South Bay garden. I couldn’t agree more with the idea of watering slowly. I water rarely in the summer, but when I do I water a lot (i.e. 1/2″ – 1″ deposition). In order to get the water to penetrate the soil, I stretch the watering out for a long time (i.e. three or four hours, or overnight). Rain gets water into hydrophobic soils because it deposits the water slowly over a long period.

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