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House Plants
Martha Maletta, Home Horticultural Consultant
Dated - January 20, 2004

Gray January. It’s the time when house plants are welcome reminders of warm seasons past and those ahead. It is also the time when it is tough to keep them flourishing. Some special precautions and care will help plants make it through this season when we most need them.

Reduced light and temperatures in fall and winter slow plant growth and reduce water use. It is easy to overwater plants now, so be sure they need a drink by feeling the planting mix first. When the surface of the mix of small plants is dry, they should be watered, but poke a finger into large pots to be certain of not overwatering. When plants need water, water generously. Adjust watering by reducing frequency not the amount of water. Plants’ needs for water will vary a lot from week to week with the amount of sun we have and the humidity levels in the home. Slow growing or resting plants should be fertilized sparingly, if at all.

When outside temperatures drop, indoor relative humidity generally drops, below levels satisfactory for plants (and people, too). A simple and effective way to provide more humidity for plants is by letting them help themselves. Group plants together and they create a micro-climate of increased humidity. Group them on a pebble-filled tray to which water can be added for an additional boost, but make sure the pots do not stand in that water. Never try to compensate for low humidity by giving the plants themselves more water. A room humidifier can be good for plants and people. Misting plants is generally not practical and not effective unless done several times daily.

Cool temperatures are recommended for winter resting plants, but few can tolerate cold. Remember that the temperature right next to windows can fall well below room temperature and low enough to damage plants. Cold drafts can be devastating, too. Move plants away from those locations or provide some extra protection.

Keeping plants free of dust, always important, is especially so in winter. Give the leaves an occasional sponge bath or shower. And be on the look out for plant pests. Check plants regularly for scourges such as mealybug, scale and white fly. Or look for signs of pests - discolored, distorted, or sticky leaves. New plants should always be “quarantined” for a month or so to make sure there are no problems that might spread to other plants.

If new, apparently perfect, holiday gift plants develop problems shortly after they have been received and no insects can be found, consider these other causes. Some plants respond to a change in environment with yellowing and dropping leaves. Ficus benjamina and Dracaena marginata are notorious for dropping leaves when moved even from one spot to another in the same room. If a new plant is appropriate for the new location, it will eventually adapt to the change. A gradual transition to different light level (especially low light) can help.

Yellowing, browning, dropping leaves could signal a more serious problem. Because of frequent watering, commercial growers use more intense fertilizer applications than the home situation requires. In the home setting, when the plant is probably maintained in a drier condition, the existing salt levels in the potting mix of a new plant may damage roots and leaves. It is a good idea to water a new plant generously when it’s brought home to wash excess salts away from the roots. There’s generally no need to fertilize new plants.

Given the right care, a holiday cyclamen can keep blooming for at least several weeks. Then it is decision time: keep the plant and try to rebloom it or discard it, let the professional growers do the work and buy a new plant next winter.

A popular holiday…and year round… flowering houseplant is the cyclamen. They are not easy to grow, however, being quite particular about having their needs for light, temperature and water met. Cool temperatures, bright light and uniform moisture are the keys to keeping cyclamen vigorous and blooming. These growing conditions mimic those of their native Middle Eastern wet, cool fall and winter. The plants are dormant during the hot, dry summers.

“Cool” means maximum 70 degrees during day - 60’s is best - and around 50 degrees at night. “Bright” means as much light as possible without direct south sun. An east window is a good choice. “Uniform moisture” means watering the plant frequently enough so that the mix does not dry out but not so often that it stays soggy. Water thoroughly but never let the plant stand in water, and do not apply water into the center of the plant. Try to provide some extra humidity.

Given the right care, a holiday cyclamen can keep blooming for at least several weeks. Then it is decision time: keep the plant and try to rebloom it or discard it, let the professional growers do the work and buy a new plant next winter.

To rebloom, the plant - actually the tuber - needs a rest. To mimic summer and force dormancy, gradually reduce watering when flowering has finished. The leaves will gradually yellow and dry up. After carefully removing the dry leaves from the tuberous stem, there are various ways to proceed. One approach is to place the pot in a cool dark place until mid to late summer when the tuber can be repotted (leaving it half exposed), watered and, when leaves appear...hopefully...grown as before with the addition of regular fertilization.

An alternative suggestion is to repot the tuber right after the dry leaves are removed, begin watering immediately and grow the plant outdoors in a bright protected location until frost threatens. Or, remove the tuber from the pot, clean it up and stored in dry peat moss or vermiculite in a plastic bag at 50 degrees. Then repot in early summer and grow as above.
The plant must grow well and develop plenty of leaves to flower well. Bright light and proper night temperatures after buds form are also important along with a big dose of... good luck.

Events

The 14th Annual Winter Conference of The Northeast Organic Farming Association of New Jersey will be held January 31, 8 a.m. to 5 p.m. at the Cook College Campus Center in New Brunswick. The conference is for the organic and sustainable farming community in New Jersey and the region, but anyone with an interest in organic growing is welcome to attend. Topics on the day’s program include: Pesticide Choices of Organic Producers; Organic Land Care [for landscape and garden]; Getting Started in Viticulture; Edible Forest Gardening. The complete conference program and registration information can be found at the NOFA-NJ website www.nofanj.org

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