WINTER GARDENING INDOORS

by Joelle Steele

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In many parts of the country, outdoor gardens become dormant or disappear entirely during the late fall and winter seasons. During those times, the emphasis on plants comes indoors. Azaleas, gloxinias, cyclamen, chrysanthemums, poinsettias, and other bloomers are for sale as indoor plants. Other outdoor plants from your garden are potted up, and along with those which are already in containers, are brought indoors to weather the cold months. You can prolong the flowering lives of many of your winter houseplants, and in some cases, you can extend their lives long enough to introduce them into your outdoor garden come spring. You can help your foliage houseplants make it through the shorter days as well.

QUARANTINE FOR OUTDOOR PLANTS

When you first bring your outdoor flowering plants inside, you should keep them in "quarantine" for a couple weeks to make sure they don't have any insects or other pests which could spread to and devastate any of your existing indoor foliage plants. If you pot your flowers up every fall, be sure that you rinse them off thoroughly and use only sterile potting soil and clean pots to prevent disease. If necessary, spray all your outdoor plants with the appropriate insecticides to eliminate any traces of white fly, thrips, aphids, mealy, etc., which they may be harboring but which are not visible to the naked eye.

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OVERWINTERING CONDITIONS

Maintaining any plant indoors takes a bit more work than it does outside. Controlling the indoor environment isn't that simple and it's harder to correctly water a potted plant inside. Most blooming plants need good air circulation, cool temperatures, about 50% humidity, and direct or indirect sunlight. These are not easy to achieve when all the windows are shut, the heat is on, the air is bone-dry, and the skies are grey. Whenever possible, keep yours bloomers in the coolest places and close to your windows — areas that are frequently one in the same. Keep your foliage houseplants in your warmer windows but away from the cold glass and out of the direct sun unless they are used to it. To maintain humidity for moisture-sensitive plants such as poinsettias, try putting a layer of pebbles in the saucer so that you can leave water in the saucer without any danger of rotting the plants' roots.

WATERING AND MOISTURE

Most indoor plants, bloomers and foliage alike, prefer that their soil be kept evenly moist since their roots are easily damaged when the soil gets too dry. But, rather than drenching them with water, try smaller, frequent waterings every two or three days and do not let water sit in the saucer for more than a couple of hours, if at all, unless you have a layer of pebbles in the saucer. Poinsettias in particular are very sensitive to water stress. They do not like to dry out and they should not be left standing in water. To ease water loss from soil evaporation, you can apply very clean, sterile mulch to the soil surface of your flowering plants or to moisture loving foliage plants. And, when you apply water, avoid splashing it onto the leaves or flowers because many plants, particularly the flowering ones, are highly susceptible to water-borne diseases such as powdery mildew.

CLEAN UP PLANTS

Keep all your houseplants looking fresh by removing old and faded flowers and yellowing or dead leaves. Do not drop them onto the soil surface of the plant. That's fine outdoors where they will quickly decompose in a natural environment. Indoors it's much better to throw dead flowers and leaves directly into the trash. Keep leaves clean by gently wiping them off with a clean, soft, damp rag or sponge. Always wash the rag or sponge off thoroughly in hot water and detergent before using it on another plant. If you find it more convenient, use soft paper towels. Many diseases and pests are spread from plant to plant by using non-sterile maintenance techniques.

Once your flowering plants have finished blooming some, like poinsettias, will retain their green foliage until the next flowering season arrives. These are the plants you should concentrate on as the ones that will be returned to the outside once the ground thaws. Remove any remaining dead flowers and leaves, and if they have long, leggy stems, cut them back being sure to leave at least a half dozen leaves per stem. Keep them evenly moist, but do not be surprised if you have to decrease the water since they will not be using as much once they have stopped blooming. As spring approaches and the days grow longer, they will probably start to get some new leaves. When the first ones appear, you can lightly apply some fertilizer formulated especially for blooming plants. To help the plant grow into an attractive shape, pinch back the new growth a little. Once the weather is warm enough, you can move them outside, preferable into a covered or semi-shaded area first where they can slowly acclimate to their new environment. Once they have adapted, you can gradually move the sun-lovers into the direct sun.

DORMANCY

Your foliage houseplants will go into a period of dormancy as soon as the days start growing shorter. You won't see any new growth and they may even look a little droopy. Unless they are in a very bright, warm window, they will require very little water during the winter months so you should cut back on watering and give them only enough to keep them on the damp side, but not ever wet. Also, do not fertilize them at all until at least a month into the spring season. As a rule of thumb, cut back or stop fertilization as soon as the fall season starts.

Some of your blooming houseplants will simply not make it through the winter. They may be annuals that were never meant to last beyond the season, or they could be weak or damaged plants similar to those found in many grocery stores where the maintenance before you buy them is haphazard at best. But, with a little extra attention and TLC, many of your flowering plants will survive to join your spring garden, and your foliage houseplants will come through their dormancy and sprout new lush green leaves for you to enjoy all year long.

This article last updated: 01/12/2000.