Garden Detective: How to get whiteflies off hibiscus, make calla lilies bloom

DEAR JESSICA: I planted calla lily bulbs some time ago. They are the sunset mix. I don’t know why, but they produced only large leaves with white speckles and no flowers. I don’t know why some have flowers and no speckled leaves, and the others have only extremely large speckled leaves. The only thing I could think of is that there might be male and female bulb plants? — Angela Amato, Garden City Park

DEAR ANGELA: There are no male-female distinctions, but there are different varieties of calla lilies, and it sounds like your mix included speckled and standard varieties. There could be a few reasons some aren’t blooming. Is this the first year you planted them? If you purchased them potted and in bloom, I would tell you they were forced in a greenhouse and have spent all their blooming energy for the year. In that case, you would reasonably expect plants to bloom well next year.

But you said you planted bulbs. If this isn’t the first year you’ve had the bulbs, I wonder if you cut back their foliage or dug them up prematurely last year. After plants bloom, their leaves get busy producing and storing food for next year’s flowers — so they shouldn’t be cut back or dug up until frost has killed the foliage. When you do remove them from the soil, brush off bulbs (but don’t rinse) and allow them to cure for a few days at room temperature, then wrap in newspaper and move to a spot that is cool (roughly 50 degrees) and dry for winter.

These plants require all-day full sunlight, consistently moist soil (not just the surface, but moisture down at the root zone, about 6 inches deep) and the right fertilizer at the right time. In spring, as plants are emerging, provide a high-phosphorus fertilizer to boost blooming. Phosphorus is the middle number in the three-number ratio provided on all fertilizer packages, so look for 5-10-5 or 0-10-0, or something similar. If your nonblooming plants are growing in or near a lawn that is fertilized, that could be to blame, as lawn fertilizer is pure nitrogen (the first number listed). Nitrogen forces plants to produce green leafy growth — great for grass — but all that energy spent growing foliage leaves little for flowers.

DEAR JESSICA: Can you help identify this flowering shrub? It’s so pretty and the flowers are a vibrant orange but I don’t know where it came from. I threw a couple of seeds in the bed from a packet labeled “Old Fashioned Garden Mixture,” but after researching all the plants listed on the package, none of the seeds would seem to produce this particular plant. I really like it and would want to grow it again next year. — Diane Rubin, New Hyde Park

DEAR DIANE: That’s Mexican sunflower. Bees, birds and butterflies love it, and it’s considered deer resistant. Plus, it actually prefers poor soil, so it’s easy to grow and doesn’t need fertilizer in order to thrive.

DEAR JESSICA: Can you tell me what these bugs are? They are all over my hibiscus plants, but they don’t seem to be doing any damage. They do fly. — Mary Ann Pugliese, via email

DEAR MARY ANN: Those are whiteflies, a common pest of hibiscus and other plants. The damage they cause might not have been visible when you snapped this shot, but make no mistake, they are injuring the plant. Whiteflies typically hang out on leaves, often on their undersides, where they suck sap from foliage. This can weaken the plant, but usually isn’t fatal. If the flies are just on a leaf or two, remove those leaves and discard them in the trash. If, however, they’re all over the plant, your best course of action is to wash them (and their eggs) away using as strong a stream from a hose as the plant can handle.