Having houseplants around us is very important, especially during the winter. They soften our space and add beauty and color to our indoor environment. In addition they absorber air pollution and provide oxygen. If you have simply been keeping your houseplants watered all winter, now is a good time to get reacquainted and check out their health.
Yellowed leaves are often a sign of a watering problem: overwatering or under-watering. Most houseplants need a thorough watering rather than just keeping the surface moist. Periodically set the plants in a sink or tub and water them until the water drains out the bottom drainage holes. Depending on the plant, some need watering more often than others. Low humidity in the house is a common problem in the winter and plants can dry out faster. Yellowing leaves may also be an indication that nutrients in the soil are depleted. Repotting in new potting soil and/or fertilizing may be the answer. Certainly, as spring is approaching, encourage new growth by fertilizing.
Every time you water the plants, check for signs of insects. Look at all visible parts of the plants, including the stems and underside of the leaves. Common houseplant pests include aphids, white flies, scale, spider mites, thrips and mealy bugs. If you discover an insect problem, isolate the plant to avoid transferring the problem to the rest of you houseplants. If the infestation is light, try non-chemical methods of control including washing with a lukewarm mild detergent solution, spraying all sides of the leaves and stems with lukewarm water and using sticky traps. Note that sticky traps will only reduce the number of insects, but not eliminate them. There are several insecticides on the market that are available in ready-to-use containers. Be certain to read the label thoroughly before use. Finally, if nothing works to eliminate the pest problem, discard the plant and soil in the trash and purchase something new that pleases you.
Houseplants need to be kept clean of household dust. Large smooth leaves can be cleaned with a damp cloth. If the plant has many small leaves, put the plant in a sink or basin and spray lightly with lukewarm water. Do not use your furniture dusting cloth or feather dusters. In addition to cleaning the plants, remove any dead or dying leaves. Use a scissors or pruner to remove the entire leaf. If a leaf is turning brown on the edges and only the brown part is trimmed, the remaining leaf edges will turn brown and die. It is best to prune the entire leaf.
Some plants like to be root bound, while others may need repotting. When repotting, you may want to divide the plant. Use new potting soil for repotting as the old soil may be depleted of nutrients or may harbor insect eggs or larvae. Garden soil and top soil are generally too heavy to be used for houseplants. Some plants such as cacti, orchids and violets require special soil mixtures. Garden centers and garden nurseries carry all types of soil mixtures.
Poinsettias are houseplants, too. At this time of year those beautiful Christmas plants are probably getting pretty scraggly looking. You can cut them back to about 6 to 8 inches and grow as a foliage plant. Poinsettias can be grown outside during the summer, but they will not winter over outside. Bring it indoors in the fall when night temps drop below 50 degrees. It is possible to get it to bloom again if it is given the light/dark treatment consisting of six to eight hours of direct sunlight followed by 12 to 14 hours of darkness for about two months. Indoor night temperatures should remain between 60 and 70 degrees.
For more specific information check the following websites: http://www.extension.umn.edu/distribution/horticulture/M1183.html and http://www.extension.umn.edu/distribution/horticulture/DG1130.html.