Text and Photos by Lee Gordon Native Garden Committee
This is fifth of a short series on some of our local native plants that are superb for our gardens, but that are largely overlooked.
Bush rue (Cneoridium dumosum), is one of our common small shrubs, found in San Diego from the coast into the foothills. Bush rue is found in a few locations to the north, but it is otherwise a truly local San Diego native. Even now, after our long dry summer and fall, most of the plants growing in our open spaces remain green.
Our local wholesale nurseries report that most of their bush rue are destined for habitat restoration rather than our San Diego native gardens. It seems that few of us are aware of how nicely bush rue works in our gardens. Two of our most prominent native plant landscape designers know better.
Clay Tschudy (executive director of San Diego Canyonlands, https://www.sdcanyonlands.org) and Greg Rubin (owner of California's Own Native Landscape Design,
Because bush rue grows in locations from the relatively cool moist coast to hot dry hills and valleys, it is adaptable to a wide range of irrigation. They do not need much water to stay vibrantly green. Watering them a few times during the hot season may be all it takes. They look good on my hill with a monthly 1 inch. The most important consideration is to avoid irrigating them too often. Bush rue grows better with neglect than it does with too much water.) have long appreciated bush rue as a backbone plant in their designs. Both design native gardens on a foundation of evergreen plants, and bush rue serves that purpose well. Bush rue is a slow growing but sturdy shrub, 3-4 feet tall and 3-4 feet wide, reaching full size in 3-5 years. It fits nicely between ground covers and full-size shrubs to add vertical interest to our gardens. I have seen some in our open spaces as tall as 6’, but their slow growth makes it easy to keep them the size and shape you want. Clay adds that their moderate size suits them particularly well for smaller gardens.
Below: This 3’ tall, 4’ wide bush rue has grown here since I first began to pay attention. It has never been trimmed. It is at the edge of where I water, & soil receives around 1/2” of water monthly.
Once established, bush rue stays green with no water at all, but as the dry season progresses, the green dulls. Fall or winter frost can turn the foliage a lovely yellow/orange. Bush rue needs full sun to be happy. I have lost plants in shadier sites.
Bush rue produces abundant scented white flowers as soon as rains end our long dry season. They bloom most often in January, but irrigated bush rue can have flowers almost any time of the year.
A few months after flowering, bush rue displays colorful quarter inch berries that look like small oranges. In fact, bush rue is a member of the citrus family.
Below: Bush rue blooming in December 2014 after good early rains. It is usually one of the first plants to bloom in the rainy season.
Below: Colorful bush rue berries come in shades of red, yellow and green. The plant holds them in the air through the summer, where they bake chocolate brown in the sun. They do not germinate until after they turn brown.
Bush rue berries can be found on plants into the late fall. The image below shows berries photographed in December. Berries turn brown in the summer and hang on the plant well into the fall. These brown berries will germinate but the red ones will not.
Later in the summer and fall, the berries turn chocolate brown, and then they are ready to germinate. Moist stratification at 55°F produces radicles in two to four weeks. I transplant the seeds when the roots appear, but you can probably get seeds to grow in well-watered pots left outdoors during the cool season.
One caution is that oils from bush rue foliage can be phototoxic. Phototoxicity can be a property of oranges and other citrus as well, and it causes some of us to blister after exposure to the plant followed by exposure to the sun. This affects relatively few people, but bush rue has caused both Greg and Clay to get blisters. I am not affected. If you are worried about it, handle the plant with gloves and wash the gloves when you are done. Greg and Clay both place bush rue away from pathways to prevent casual contact. This sounds to me like a great opportunity for a border of willowy mint planted in front of the bush rue!
Next month: Scrub oaks