Calliandra, commonly known as powder puff plants, are fairly common landscape plants in the tropics and subtropics (they are regularly seen growing in the steamy Zone 10 in South Florida). There, they are grown as small trees with woody stems and especially prized for their profuse displays of red “powder puff” flowers that blanket the tree every year. The puffs are actually the stamens of the flowers, and they really are beautiful. Indoors, these plants are kept smaller by necessity and, under the right conditions, can be coaxed into winter blooms or year-round blooms. Even though they are somewhat drought tolerant, they are not especially easy to bring to bloom inside. They are sensitive to cold, dry air, which perfectly describes the conditions in many homes. Even if the plant doesn’t bloom, however, its fern-like, segmented leaves are drooping and beautiful.
Calliandra needs bright light—especially indoors, the more the better. During the height of the growing season, they might need protection from direct sunlight that is magnified by windowglass, but generally for the rest of the year, they like very bright, direct light.
During the growth season, water frequently and never allow potting soil to dry out. You can reduce watering somewhat during the winter, but because the most common species is a winter-bloomer, you never want to completely suspend watering.
A rich, peat-based potting soil with excellent drainage is beneficial.
Feed with a weak liquid fertilizer
throughout the growing season. Cut fertilizer back to once a month or so in the winter.
Calliandra can be relatively easily sprouted from stem cuttings. During the spring, when new growth emerges and the winter bloom (if there is one) has faded, take a cutting and pot it in seed-starting soil. Rooting hormone and bottom heat increase your chances of success. These are not especially fast-growing plants, so don’t expect a bloom that first year.
Repot in the early spring (when you take cuttings). In their native habitat, powder puff plants grow to medium-sized shrubs or small trees, depending on the year-round conditions and species. Indoors, they won’t become that large, but if your plant is very healthy and thriving, it can easily outgrow your pot and overpower the space. To keep it smaller, only repot every other year.
There are hundreds of species of calliandra, all native to the New World. Of these, only two are regularly seen in garden centers. Both can be grown successfully indoors:
- C. haematocephala. Native to Bolivia, this plant becomes a small tree with many-segmented, eight-inch leaves. The flower clusters are bright red, although it is sometimes called a pink powder puff. This plant is synonymous with C. inaequilatera.
- C. emarginata. Perhaps a better specimen for indoors, native to Mexico. This plant is naturally smaller than its cousin and blooms year-round under the right conditions. It is somewhat less drought tolerant than other powder puff species.
Powder puffs are not especially difficult to grow indoors, but it can be tricky coaxing them to bloom. They prefer regular moisture, high humidity, bright light and high temperatures. In the absence of these conditions, they will not grow as vigorously and will likely not bloom at all. If you have a conservatory or sunroom, you’ll likely have more success. Calliandra are not especially susceptible to pests, but will sometimes suffer from infestations of mealybugs
, and mites. Signs of infestation include tiny webs on plants, clumps of white "powdery" residue, or visible insects on the plant. Treat infestations as soon as possible to prevent them from spreading to the rest of your collection. As always, start with the least toxic treatment option first, only progressing to more serious chemicals if your initial efforts fail.