   Indoor Plant Care - June 20, 2007 Jeff Schalau, Associate Agent, Agriculture & Natural Resources, Arizona Cooperative Extension, Yavapai County Indoor plants can create a cool, spacious indoor environment while adding color and interest. While indoor plants can thrive in some settings, many homes and other indoor spaces are poorly suited to their needs. Growing indoor plants successfully is dependent upon selecting plants that are best suited to available growing conditions, providing proper care to maintain health and vigor, and monitoring for insect and disease problems. Light is probably the most essential factor for house plant growth because it is the energy source that drives photosynthesis. The direction the windows face affects the intensity of natural sunlight that plants receive. Southern exposures have the most intense light, eastern and western exposures receive about 60% of the intensity of southern exposures, and northern exposures receive 20% of a southern exposure. Curtains, trees outside the window, weather, season of year, shading, and the cleanliness of the window also affect light intensity. Increased hours of lighting allow a plant to make sufficient food to survive and/or grow. However, plants also require some period of darkness to develop properly and should be illuminated for no more than 16 hours per day. Plants receiving inadequate light may have elongated stems, small/pale leaves, and/or exhibit poor growth. Excessive light can also be harmful. When a plant gets too much direct light, the leaves become pale, sometimes sunburn, turn brown, and die. During summer it may be necessary to protect plants from too much direct sunlight. Over- and under-watering account for a large percentage of indoor plant losses. Some plants like drier conditions than others. Differences in soil or potting medium and environment also influence water needs. House plant roots are usually in the bottom two-thirds of the pot, so do not water until the bottom two-thirds starts to dry out slightly. To determine whether or not a plant needs water, stick your index finger into the pot about one-third the overall depth of the soil. If the soil feels damp, don't water. Keep repeating the test until the soil is barely moist to the touch. When it’s time to water, irrigate the pot until water runs out of the bottom. This serves two purposes. First, it washes out all the excess salts (fertilizer residue). Second, it guarantees that the bottom two-thirds of the pot, which contains most of the roots, receives sufficient water. Do not let the pot sit in the water that runs out. Watering frequency will vary by season and increase as the plant grows. If your finger can't penetrate 2 inches deep, you either need a more porous soil mix, or the plant is becoming root-bound. In general, foliage house plants grow best between 70 and 80 degrees F during the day and from 60 to 68 degrees F at night. Excessively low or high temperatures may cause plant failures, stop growth, or cause spindly appearance and foliage damage or drop. A cooler temperature at night is actually more desirable for plant growth than higher temperatures. Humidity can be increased by ether using a humidifier or placing gravel trays under the flower pots or containers. This will increase the relative humidity in the vicinity of the containers. As the moisture around the pebbles evaporates, the relative humidity is raised. Air conditioning and heating dries plants rapidly and can overtax their limited root systems. Placing plants too close to air registers can lead to cause damage or plant loss. House plants require fertilization due to the limited root space in pots. Commercial fertilizers used for house plants are sold in granular, crystalline, liquid, or tablet forms. Each should be used according to instructions on the package label or even more diluted. As a general rule, use a fertilizer recommended every 2 weeks from March to September. During the winter months no fertilizer need be added at all because reduced light and temperature result in reduced growth. The guidelines listed above are a simple overview, but provide the basics for growing indoor plants successfully. The University of Arizona Cooperative Extension has publications and information on indoor plants. 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 cottonwoodmg@yahoo.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/. |