Some blooming houseplants love bright sun, but others thrive in filtered bright light. A few even bloom in relatively low light. Light is not the only variable that affects blooming, though. Soil moisture, fertilizing, and temperatures play a role, too.
Here are some favorites that bloom reliably, are easy to care for, and are readily available from garden centers and mailorder growers:
Flamingo flower: Anthurium (Anthurium spp.), or flamingo flower, is closely related to the peace lily. It needs similar growing conditions, with one major exception: Anthurium requires more light to bloom well. Mine blooms constantly in a west-facing bay window, with sheer shades lowered in summer to protect it from intense sun.
In recent years, plant breeders have developed new types of anthuriums. You might find one with a curly spadix or unusually colored spathes, some of them quite small. But the most popular plants produce large, waxy, heart-shaped spathes that start out dark pink or red, then turn greenish as they mature. For a long-lasting cut flower, harvest a flower stem and display it in a vase—it won’t hurt the plant.
African violet: Probably the most common of all flowering houseplants, this member of the Gesneriaceae family is a favorite of indoor gardeners. African violets (Saintpaulia hybridus) are easy to grow, which explains their popularity—that, and the beautiful flowers they produce in relatively modest light. There are thousands of cultivars, and the list keeps expanding.
Use a peaty potting mix for African violets. Most garden centers have potting soil and fertilizer labeled specifically for African violets. Water thoroughly whenever the soil surface feels a bit dry, and spill out any excess water that flows through the drain hole. Many insist these plants should be “bottom watered” (allowed to absorb water from a saucer) because their fuzzy leaves are prone to water spots. If you use this technique, water thoroughly from the top every six to eight weeks to flush accumulated salts from the soil. Bottom watering isn’t necessary, though, if you direct water toward the base of the plant and keep its foliage dry.
African violet grows best in bright, filtered light, but will bloom in a north window—though less frequently. It won’t bloom in a dark corner or in intense sunlight. It’s an excellent choice for growing under fluorescent lights, where it often blooms continually. The plant grows best in relatively warm temperatures.
Use a very weak fertilizer solution with every watering, or fertilize at half strength every two or three weeks when the plant is growing actively. Almost any houseplant fertilizer will do, provided it is balanced or has a higher phosphorus than nitrogen percentage.
Cape primrose: An African violet relative, Cape primrose (Streptocarpus spp.) should be grown more often than it is. Its large, velvety blossoms are borne on wiry stems that arch over strap-like, stiff leaves. Flower colors are similar to African violet—deep purple, maroon, blue, white, lavender, and many shades of rose and pink. Its needs are different from African violet in two areas: It requires brighter light year-round and filtered light in summer, and it blooms best when temperatures are on the cool side (50ºF to 65ºF), particularly at night.
When Cape primrose gets too scraggly—it’s less tidy and compact than African violet—it’s easy to start new ones from a leaf cutting. Remove a medium-sized leaf and cut it almost in half, lengthwise. Keep the portion that contains the mid-rib, and plant it horizontally in moist potting soil so the mid-rib is buried. Small new plantlets will form all along the mid-rib.
Peace lily (Spathyphyllum spp.), sometimes called white anthurium, is a member of the Araceae family, a large group of plants encompassing some of our best houseplants—Chinese evergreen, philodendron, arrowhead vine, and dieffenbachia. (Jack-in-the-pulpit and calla lilies are also in this family.) Their flowers are minuscule, packed together on an elongated structure called a spadix, with a showier sail-like spathe behind it.
Peace lily does well in low light. It blooms sporadically in a north-facing window or several feet away from brighter exposure, but will bloom year-round in an east-facing window or in bright, filtered light. Flowers (spathes, really) unfurl pure white, then slowly fade to green over many weeks. To encourage more blooming and keep the plant looking its best, remove flower stalks once spathes look greenish.
Keep the potting soil evenly moist, watering thoroughly whenever the surface feels slightly dry. Spill out excess water that flows through the drain hole. Peace lily tolerates low humidity and does best in relatively warm conditions with nights no lower than 62ºF and days up to 80ºF. Fertilize lightly during periods of active growth, which typically lasts from late winter through early autumn.
Wax plant: This old-fashioned vining houseplant (shown above) belongs to the Asclepidaceae (milkweed) family, and it’s often referred to simply as hoya. A slow-growing succulent with plump, leathery leaves, hoya (Hoya carnosa) thrives in bright light and prefers well-drained soil that’s allowed to grow quite dry after watering.
Hoya’s reputation for being slow to bloom is well-deserved. It often takes years of good care before hanging clusters of star-shaped, velvety blossoms develop, but it’s worth the wait. The flowers are not only beautiful, but also delightfully fragrant at night. Flower clusters reappear annually on the same short spurs that hang from hoya’s woody vines. Don’t prune those vines; train them up supports or twist them in big hanging loops.
Keep hoya cool (it can tolerate temperatures in the low 50s without being damaged) and make sure it’s dryer in winter than in spring and summer when it’s growing actively. Fertilize only when it’s putting on new growth, usually from late winter or spring through summer. If you’re lucky, you may see two flushes of bloom each year.
(Deborah Brown is professor emeritus, University of Minnesota Department of Horticultural Science, and “Expert Advice” columnist for Gardening How-To)