Ceanothus varieties that thrive on neglect

29 July 2008 Prev Next

Over the past few years, Krzysztof Kozminski has planted many ceanothus varieties – and many plants of each variety – and has become an expert in which ones are the most forgiving of neglect. None of the plants are watered after they have been in the ground one year. Last month's column described his planting method on a hot, dry slope in San Jose. Good drainage is a must for ceanothus, so if you don't have a slope, you can improve drainage by planting on a mound at least a foot high.

One of the main advantages of not watering ceanothus after the first year is that it may increase their longevity. It's not uncommon to hear that ceanothus are short-lived in gardens, but this is probably because most varieties have limited tolerance for garden water.

At a talk sponsored by the Gardening with Native group, Kris discussed his seven favorite varieties of California lilac, or ceanothus.

Trewithen Blue ceanothus (C. arboreus 'Trewithen Blue') grew 5 to 6 feet high within one year and flowered profusely from mid-March to the third week of April. This selection of island ceanothus drops half of its leaves by July. Selected from a garden in Cornwall, England, for its vivid blue flowers, its mature height is 15 feet.
Buckbrush (C. cuneatus) grows all over California and has sparse white flowers from early March to mid-April. It can take a lot of neglect, and has survived with a single watering after planting. Along with chamise, buckbrush is the most common plant in the Mt. Hamilton range, so it's a good plant for local wildlife and for restoration projects. It can reach 10 to 12 feet.
San Diego ceanothus (C. cyaneus) holds its spikes of blue flowers high above the light green foliage, from the end of April to late May, like a blue cloud. It can grow up to 12 feet.
Mt. Vision ceanothus (C. gloriosus porrectus) is a mounding groundcover that looks good all year. From mid-March to mid-April it sports some blue flowers. It can grow 2 feet high and up to 7 feet wide. A coastal species, it usually needs some afternoon shade inland.
Santa Barbara ceanothus (C. impressus nipomoensis), another coastal variety, is surprisingly clay-tolerant on a slope. Pink buds open to profuse blue flowers from late March to late April. It gets 2 feet high and 3 feet wide.
Napa ceanothus (C. purpureus) looks good all year and has purplish flowers fading to white during March. It can get 3-6 feet high and 3 to 9 feet wide. Blue Jeans, a hybrid selection related to Napa ceanothus, is more widely available and just as easy to grow.
Arroyo de la Cruz ceanothus (C. thyrsiflorus thyrsiflorus 'Arroyo de la Cruz') grows very fast and is very forgiving of neglect. Sky-blue flowers appear from late March to the end of April. After a year it was 2 feet high and 4 feet wide, increasing to 4 x 6 the next year, and 8 x 6 the third year.

To obtain these plants and other natives, try the nurseries specializing in native plants (Yerba Buena, Native Revival, Gold Rush, Bay Natives, East Bay Wilds). Local varieties are often available at California Native Plant Society or botanic garden (Tilden, SF, Santa Cruz, Berkeley) sales. For the southern California selections, you can mail-order from Las Pilitas. One of the easiest ways to obtain natives is by placing a special order at your local independent nursery, which gets the plants from one or more wholesale nurseries specializing in natives, such as Suncrest Nurseries or Native Sons.