Q. How can I get my tuberoses to bloom? I have three bulbs planted in 6-inch pots that I bring indoors during winter. Last season, I had lush foliage but no flowers. The year before, I had only one flower in late fall.
-- Lynda Montgomery,
A. It sounds like your tuberoses (Polianthes tuberosa) might be just about ready to bloom when the weather turns cold.
Tuberoses are slow-growing, summer-flowering bulbs that need four to five months of warm weather and abundant moisture to bloom. In Mexico, where they are native, and Hawaii where they are grown to make leis, tuberoses flower easily. But plants need a head start here in the Midwest where the growing season is shorter and periodically drier.
This March, move your container-grown tuberoses to a warm spot in bright light and resume regular watering. Once they are actively growing begin fertilizing regularly. Wait until the danger of frost is past to move the pots outside. A spot in full sun usually means earlier and better flowering, but tuberoses will tolerate shade.
Consider replanting your tuberoses into larger pots. Plants up to 3 feet tall grow best when planted 3 inches deep and 6 inches apart. Use fresh, moisture-retentive soil and only pots with drainage holes. Tuberoses need consistently moist soil and larger pots also will make it easier to keep them properly watered.
Fragrant flowers should bloom from midsummer through the first light frost, when it's time to move the pots back indoors to rest in a cool, dark spot.
Q. Ten years ago, I grew a bird of paradise plant from seed. It looks healthy but has never bloomed. What should I do?
-- Jeannine Denning, Madison, Wis.
A. It's possible your plant just needs more time. Bird of paradise (Strelitizia reginae) usually needs at least four years to begin flowering, but it's not uncommon for blooming to take 10 years or more.
To encourage your plant to bloom, allow it to become root-bound. Instead of regularly repotting it, keep the plant snug and happy by adding just a layer of fresh potting soil each spring.
You also might consider supplemental lighting. While the foliage looks healthy, to produce flowers that bloom in late winter or spring, bird of paradise needs as much bright light in fall and winter as it does in spring and summer.
Finally, evaluate your fertilizer schedule. Bird of paradise needs water-soluble fertilizer every other week in spring and summer. Too little fertilizer can inhibit flowering; too much can produce lush foliage at the expense of flowers.
Denise Corkery writes for the Chicago Botanic Garden in Glencoe. Write to: Gardening Q&A, House&Homes, Chicago Tribune, 435 N. Michigan Ave., Chicago, IL 60611-4041; e-mail to house& firstname.lastname@example.org.