Gardening with Gary

Gardening Advice from an Expert

Gloxinia

Q. My gloxinia is a florists gloxinia. Can you give me some info please. Is it true they can't last thru the winter because they're florists gloxinias?

A. Florist Gloxinia is a member of the Gesneriad family, just as are African violets and streptocarpus. They are in the genus Sinningia and are different from the Gloxinia. They have a large tuber underground where food is stored. They come up and bloom massively and then take a rest, dying all the way back. Old foliage is removed and the pot is placed into a dry dark spot to rest. Several months later, shoots will appear, plant is moved back into the light, watering and fertilizing is resumed and flowering follows.

They will last for years if properly raised. They are very sensitive to water. Too much in a compacted soil mix will lead to root and tuber rot and death. Repotting should be done every year, after they have gone dormant. Brush off old soil and place into new, fresh organic potting mix with some perlite added.

They respond well to feedings of Peters, Optimara, Dyna Grow and Miracle-Gro. Also, give them good indirect light or place under fluorescent plant lights.

Additional information can be located at www.avsa.org under Other Gesneriads.

Olinda writes~
I have a large tubular flowering plant which someone told me is a Gloxinia. It is growing well and has had a couple pretty flowers, but I see round brown spots on a couple leaves. Why is that happening and will it kill the plant?

A. You do indeed have the Florist Gloxinia--Sinningia speciosa:

The Gloxinia [a relative of the African violet] begins to die back naturally in the fall and should be allowed to do so to complete this phase of its life. Allow the tubers to dry completely. Restart the plant by dividing the tubers and when new foliage appears, you can further propagate by taking leaf cuttings.

With the florist gloxinia, the soil needs to be kept moist, but not soggy. Fertilize with a flowering houseplant material every two weeks, and keep in bright, but indirect light, in a warm location (70 F+), free of drafts. After flowering, the plant will go into a dormancy, so back off on the watering and allow the plant to dry down. Store at about 50 F in a dry, dark spot in the pot and then repot in fresh humus/compost potting soil next spring.

Gloxinias are not very forgiving of any human misgivings. They need to be kept moist--moist soil, not the foliage--with tepid water. They require high humidity, which is accomplished by placing the plant on a water-filled pebble tray or place containers of water around the pots.

They also need bright, but indirect light--no direct sunlight. Allowing the sun's rays to reach the plant would be one of many causes of spotting on the foliage and flowers. As a sweeping generalization, it is usually the dry air of winter heating units t hat causes the most trouble. That, or a cold draft of air could cause brown spots on the leaves.

Gloxinias are purchased as tubers in the spring and brought into flower in summer. You will know when that period is over when new shoots become visible. Then, the life cycle starts over again.