Plants with Panache - Ricinus communis 'Carmencita' ((under construction))
Plant Family: Euphorbiaceae (spurge)
The tender, shrubby castor bean is a half-hardy annual that often performs like a short-lived evergreen perennial in my Northern California garden, growing from 3 to 15 feet tall and 3 feet wide with broad, deeply divided palmate leaves that can reach 12 to 18 inches across. The only species in the genus, R. communis has foliage and stems that are generally green or an undistinguished gray-green. The choice variety, 'Carmencita,' is strikingly colored, with ornamental foliage a mahogany to red to purple hue. Look for the eye-popping inflorescence, with insignificant flowers that form as summer draws to a close, followed into the fall by brilliantly red spiny seedpods held aloft on long stalks (peduncles). Especially on older plants, main stems become woody and the upper growth noticeably softer.
The profile of the seed is the basis for the botanical name, which means common tick!
Note: All plant parts are poisonous, particularly the seeds, so you won't want to grow castor bean around children.
In a hot, sunny location, castor bean flourishes in humus-rich, well-drained, moisture-retentive soil. Under these conditions, plants may grow treelike in two months' time. Plant seeds directly in the ground when all chance of frost is past. In late spring, before the ground warms, you can grow seeds indoors in peat pots for four to six weeks, then settle the potted seedling in a spot where the showy plant architecture is meant to be a focal point. Young, self-sown plants do not fare well when pulled up and relocated. In general, castor bean roots should not be disturbed.
Listed as an invasive plant in Florida and Hawaii, I find that in my Marin county garden, with frosty nights and soggy winter soil, almost every self-sown seedling is killed off.
If you're going for a tropical look, castor bean is an unbeatable specimen for containers or in the ground. Still, in the first growing year, gardeners should monitor plants to be certain that not too many plants survive the winter and that none escape from the garden.
If a problem is identified, it's good practice to clip off the entire flowering stalk as soon as the seedpods begin to fade, so there's no possibility of plants overwhelming an area. Or focus on the dramatic foliage and immediately remove any flowering racemes as soon as they emerge.
If you do clip the stalk after seed capsules form, you can harvest the beans to propagate more plants. Once the capsules mature, they begin to split, making it easy to collect the seeds. Store in a clean, dry container and label it clearly.
For a handsome plant marriage, combine castor bean, with its oddly thorny seedpods, and clary sage (Salvia sclarea), a floriferous biennial herb boasting terminal spikes & showy bracts.
I've witnessed surprising differences in the size and longevity of plants in my garden. One towering plant developed a central treelike stem and a sprawling branching habit, living for three years. Another remained compact and never thrived.
Provide good air circulation and a consistent temperature of 60 degrees or warmer to avoid seedling blight when propagating. Plants in the garden are generally trouble free.
Plant society seed exchanges can be a source for castor bean seeds.
Thompson & Morgan at times offers seeds of Ricinus communis 'Carmencita' online at www.seeds.thompson-morgan.com.