California Landscape Design

Beyond Juncus: Fresh Planting Ideas for Rain Gardens

Marilee has committed herself to improving the landscape of Los Angeles.  She sees potential, applies alternative, responsible, sustainable principles and develops projects that consider land stewardship, potential local impact, water conservation, soil health, and the overall environment. She has participated in award-winning rainwater harvesting projects, LEED projects, water conservation demonstration gardens for public agencies and gardens funded by Santa Monica Sustainable Landscape Grants. As President of Urban Water Group, Inc. she oversees the design, budgeting and construction management of each project, drawing on her expertise in rain water harvesting, infiltration systems, LID (Low Impact Development) Best Management Practices, climate appropriate planting, and efficient use of potable and alternative water sources.

Marilee also currently serves as a member of the Los Angeles Community Forest Advisory Committee, as a landscape consultant for the City of Santa Monica, as a board member of theSouthern California Horticultural Society,  and speaks to groups all over southern California about water conservation and the importance of watershed awareness.

"Plants that can thrive in swales or rain garden are plants that I’ve been hunting down for a few years now. It’s not functional or aesthetically pleasing to my eye to fill a rain garden or swale with rocks or gravel, over time if a swale or rain garden doesn’t have plant roots, it will not drain as effectively as it will with roots to keep the soil open and stable and the biological activity in the soil thriving. But only gradually has my swale plant list grown. The list is constantly being edited—sometimes expanding, sometimes shrinking—as a result of testing prove that a plant doesn’t like the conditions of particular area.

My list started like most swale plant lists started with Juncus, which is a fine plant if you like stiff perky green forms. I like a bit more variety and a more of a curvy form to make a swale look natural or more relaxed. Streams curve, storm channel are stiff. I am always on the lookout for plants I can add to my list. These plantings can be tricky. In Southern California it rains only in the winter thru spring and then nothing for 9 months of the year, so plants in these areas may be covered in rain water for some period of time depending on how quick the swale/rain garden drains and the frequently and intensity of a rain shower and they might be rained on day after day, then nothing for weeks, then nothing for months. I prefer not to add irrigation to a swale for the dry times. 

I take trips just to botanize in Mediterranean regions. Learning what plants do in their “natural” environments in the regions where they grow is a very informative way to learn what plants need or how they like to behave. While botanizing in Western Australia, a climate very similar to my So California roots and where I currently practice, I asked Warren Roberts one of my fellow travelers what his experience was with plants that would do well in a swales / rain garden situation. For the next 2 and a half weeks, Warren would ask for my notebook and write down another plant name that he thought would be of use and tell me a little about it, what position in the swale it would prefer or if it had other interesting and useful characteristics. The list was not extensive, but it was more than I had so I was excited to start testing my new-found friends as soon as I got home. On looking further into each plant some were just too wild looking for a typical groomed landscape or unavailable in the nursery trade, but it did open up a new way of thinking as I read each description. I started to notice the natural swale conditions we were traveling though on each trip I took, asking locals or guides for their options of what might work. Any time I saw a dry creek bed I would examine the plants that were present to try to determine their natural water flow frequency and time of year. This has now become a habit when I am on botanizing trips but now I look for other plant characteristics; 1) what is growing in a swale and what is its position; 2) does it go summer dormant; 3) does it grow chasmophytically, (on the rock cliffs or crevices) getting no irrigation at all; 4) overall appearance. All these can be useful in a swale design: which position would best suit its habit, which ones should be up out of the water line above the swale that gets no irrigation at all and may love to scamper over the boulders and rocks.  

I passed a grove of Alyogyne huegelii in the sand bar of a river flood plain while on the Western Australia botanizing trip and thought wow I never thought of using that plant in mass like that, how gorgeous is that idea. When I got home I did a little research and some thinking on its position in the riverbed. Wikipedia says it likes Coastal Sandy Soil… I think it just might like to be in a rain garden in the upper position, so I am currently testing how it does in that position.

The Anemopsis californica Warren introduced first to me is now on my permanent list. Its layering habits can cover the bottom of a swale in a minute but its just great to have a big leaf in the swale along with the Juncus.

I use Carex sedges to sup up water in a lined swale and also an unlined swale. The clumping species do well when covered with water and the runners do well holding the structure together where there are fast flows. Some can go summer dormant coming back to life with  the first rain of the season."

FOR THE BOTTOM OF THE SWALE:

Anemopsis californica, YERBA MANSA*

Carex barbarea, SANTA BARBARA SEDGE*

Carex praegracilis, CALIFORNIA FIELD SEDGE (good near inflows for erosion control)

Distichlis spicata, SALT GRASS*

Hibiscus lasiecarpus (syn. H.californica), ROSEMALLOW*

Juncus, many species & cultivars, RUSH (I like Juncus inflexus, 'Afro' & ‘Elks Blue’)

Salicornia, PACIFIC SILVERWEED*

FOR THE SIDES OF THE SWALE:

Alyogyne huegelii, BLUE HIBISCUS (upper sides)

Iva hayesiana, SAN DIEGO POVERTYWEED* (upper sides)

Lomandra hystrix cultivars, MAT RUSH (midpoint or higher)