Euphorbia (yoo-FOR-bee-uh) is a diverse group that includes a variety of fierce and exotic looking succulents. These oddballs are easy to grow and make quite a statement when potted solo or in arrangements. Use caution when handling Euphorbia, as they contain a caustic white sap that causes skin irritation.
Form: Succulent Euphorbia can take a lot of different forms including thick, water-storing trunks, pencil-thin stems that stand up or sprawl, and large, intimidating thorns.
Colors: Varies greatly in this genus, with some varieties displaying vibrant orange and red tones and others in frosty blues, silvers, and greens.
Foliage: Not all succulent Euphorbia have foliage, but some are topped with large, thin leaves.
Flowers: Unique from the rest of the plant kingdom. The structure that resembles a flower is actually a "cyathium" or cluster of simplified male flowers and one larger female flower. Below the flowers are colorful pairs of cyathophylls that look like petals but are more like leaves (more info).
Light: In general, give lots of direct sunlight to encourage growth, though Euphorbia can also tolerate indoor light conditions for long periods of time.
Soil: Pick a gritty, well-draining mix like a cactus and succulent soil (available at garden centers) or mix your own (more info).
Water: Water deeply enough for water to run out the container’s drainage hole. Allow soil to completely dry before watering again. Keep dry in winter.
Hardiness:Euphorbia are not frost hardy and should be brought indoors to a sunny window sill if there is a chance of frost. (What’s my zone?)
Propagation: Most produce new offsets around their bases and can root from stem cuttings (use gloves and eye protection to avoid contact with sap). Euphorbia is also one of the easier varieties to propagate from seed.
NOTES FROM THE NURSERY
This genus includes at least 2,000 extremely variable species, most of which are not succulent (e.g. poinsettias). The 500-600 succulent Euphorbias share sweet, round flowers and a white, latex sap that can irritate skin. They are easily mistaken for cacti, though the two are unrelated.
Euphorbia can display a wide diversity of forms, partly due to their extensive geographical distribution throughout the Old World. The flower structure is unique from those of all other plants and Euphorbia is the only genus known to utilize all three photosynthetic pathways (C3, C4, and CAM).
Because they are adapted to a wide geographic range, different species of Euphorbia have different care needs. For the most part, a normal succulent regimen of bright sun, rapid drainage, and deep but infrequent water suits them just fine. They tend to be summer growers and should be kept fairly dry during their winter dormancy.