Houseplant growing conditions are rarely as good as native conditions. It is even more critical that the potting mix be of good quality. It must be porous, yet able to retain water and nutrients.

Most commercial potting mixes are soilless. Soilless mixes have the advantages of being light, easy for roots to penetrate, and free of insects and disease. High-quality mixes contain slow-release fertilizers that provide nutrients for several months. Inexpensive potting soils are found in many retail stores. They are often very dark in color because they contain large amounts of organic matter. Problems arise because these mixes compact readily and retain too much moisture. The home gardener can prepare soilless mixes at home. One mix that can be used for starting seeds or growing houseplants is the Cornell “Peat-Lite Mix A.” The recipe follows:

One Peck Mix One Bushel Mix

Vermiculite #2 size 4 quarts 1/2 bushel Shreaded Peat Moss 4 quarts 1/2 bushel Limestone 1 tablespoon 5 tablespoons Superphosphate (20%) 4 teaspoons 2-1/2 tablespoons 5-10-5 1-1/2 - 3 tablespoons * 6 12 tablespoons * i * Use the lower rate for sowing seeds.

Slightly moisten the peat moss prior to mixing. The mix can be used immediately or stored until needed. Keep the mix moist during storage (such as in a plastic bag) which makes it easier to use. Be careful not to overwater, as it is difficult to dry the material out once it is saturated. When plants will remain in the mix for long periods of time, apply a water soluble fertilizer about every two weeks.

Potting mixes that contain mineral soil provide larger plants more stability because they are heavier. For larger plants, a potting medium containing soil is best. However, homemade mixes that contain soils have several disadvantages. Finding good quality topsoil is often difficult. Garden soil will contain pathogens and insects. Before using garden soil, it should be pasteurized. A growing mix that contains soil has a tighter structure and less pore space for root growth. It must be amended with equal volumes of organic matter, sand, and vermiculite or perlite.

Be aware of the special potting media that should be used with some plants. One group of plants, EPIPHYTES, are grown on pieces of bark or potted in a special mixture that may contain sphagnum moss, bark, or plastic chips. Know the proper soil for the specific plant.