   Winter Care for Indoor Plants - January 12, 2005 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Most, but not all, indoor foliage plants are native to tropical areas. This is why most indoor plants prefer a humid atmosphere and indirect light. During Arizona winters, we usually have enough light, but humidity is often low. This is especially true when outdoor temperatures are below freezing and the indoor environment is heated without humidification. To successfully grow house plants, you must learn sound cultural methods and pay careful attention to the plant’s appearance and soil conditions. Most people depend on natural window light for the growth of their plants. Natural light may be adequate if plants are close to windows. However, the amount of natural light a plant receives, decreases dramatically the farther it is placed from the window or its source of light. Usually, plants must be located close to windows to receive enough light for them to grow and flourish. If plants are not receiving enough light, their growth will be spindly and the leaves may turn yellow and die. Some plants can survive with lower light intensities such as: Sansevieria (snake plant), Aspidistra (cast iron plant), and Aglaonema (Chinese evergreen). Hanging basket planters, glass shelves, or bay window greenhouses can create extra growing space for plants that require higher light intensities. Light from reading lamps is also beneficial, but the new “broad spectrum” fluorescent lights are usually better. Generally, artificial, fluorescent light 10 to 14 inches above the plants will provide sufficient light for plants requiring medium light intensity, such as the pothos. If you use fluorescent light, remember that as they age, they fail to produce the proper wavelength for growth and should be replaced. For even growth, turn the plants once a week so they receive light on all sides. Most indoor plants grow well between 60 and 75 degrees F. They may become spindly if kept warmer. Always keep plants away from hot or cold drafts, warm appliances, and heat registers. Temperatures above 75 degrees F increases stress and make plants spindly as well as less resistant to disease and insect attack. Most indoor plants require higher humidity than that of the average home. Sprinkling or syringing plants with water is not effective as the water evaporates rapidly. Growing plants on a tray of gravel with moisture in the tray is a more practical method to raise humidity. Improper watering is the cause of most house plant problems. Both under- and over-watering can cause leaves to yellow and fall. Check plant soil daily to see if they need water. With small plants, weight is a good indicator of when water is needed. Dryer plants feel lighter than those with moist soil. Otherwise, stick your finger into the soil medium. If it feels dry ¼ inch deep, then it could probably be watered. When needed, add water until moisture drips out of the drainage hole of the pot. Wait a few minutes and water the plant again until moisture drips out of the drainage hole. Be sure to discard drainage water. Never allow the bottom portion of the pot to stand in water. Water all plants from the top at least once a month to leach salts. A build-up of white or brown crusty material on the soil or rim of the pot indicates salt accumulation. Indoor plants also require fertilization although the requirement is lower in fall and winter than it is during the spring and summer. Many indoor plant gardeners like using the water-soluble fertilizers such as Miracle Gro, Peters, or Shultz. These fertilizers are convenient and have the advantage of not burning plants, as stronger fertilizers might. However, they must be applied frequently, usually every 2 weeks. Another fertilizer option is a timed-release product such as Osmocote. They are sold in small-sized bags and bottles and contain fertilizer pellets coated with a plastic polymer that causes the slow, timed break down of the fertilizer into the soil. Timed release fertilizers have the advantage of reducing the frequency of application. Growing house plants can be tricky, but the best thing you can do is keep a close eye on them. You can also increase your success by learning which plant species suit your home’s growing conditions. Naming of companies or products is neither meant to imply endorsement by the author nor criticism of similar companies or products not mentioned. The University of Arizona Cooperative Extension has publications and information on gardening and pest management. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |