On Gardening/Problem-Free Houseplants

11-10-97
University Park, Pa. -- Some homeowners become discouraged when they are unable to maintain a variety of plants indoors. Granted, most plants require some care and attention to survive indoors. Cacti and succulents, however, will survive on a minimum or care, at least in the winter months, and may be a group for you to consider.

Sunlight is essential and windows with a southern or western exposure are the best location for cacti and succulents. A few will grow under artificial light, but natural light is still the best.

Cacti and succulents are dormant during the winter months, so they will need less water at this time. During active growth periods in spring and summer, these desert plants actually consume as much water as foliage plants. Your watering schedule will have to change at that time to meet the demands of the plant. During late October and November you should be gradually reducing the amount of water available for these plants.

Like other indoor plants, water cacti and succulents thoroughly. A light, shallow wetting of the soil surface is equal to no water at all as far as the root system is concerned. Pots should have adequate drainage holes so the roots never stand in water, not even for a short period of time. The popular wick watering systems are not suited to these plants because the soil should be allowed to dry out between waterings. It is easier for them to survive when the soil is dry around the root system.

Cacti and succulents are well suited to the cooler indoor temperatures we are beginning to adopt. Exposure to temperatures between 40 and 90 degrees for long periods is not harmful. Most homes are considerably cooler than 90 degrees, but many desert plants will develop flower buds when grown in cool, dry, well-lighted rooms.

Not all succulents are suited to a dry soil mixture. The Christmas and Thanksgiving cactus prefer soils that are higher in organic matter. They don't tolerate dry conditions and they must be maintained under a more uniform moisture level. This means watering them on a regular basis to keep the soil damp.

The cultural needs of both cacti and succulents are similar, but the two groups are quite different in their characteristics. Cacti are desert plants that feature thickened stems covered with prominent spines and usually no leaves. Succulents will usually have more slender, thornless stems and thicker leaves.

A few of the more interesting cacti you might consider include:

-- Rat-tail cactus, a spiny plant with small reddish spines.

-- Old Man Cactus, a spiny plant covered with long, silver-white hairs.

-- Peanut cactus, a plant with rows of soft, bristle-like white spines on each of the many branches protruding from its base.

-- Barrel or Fishhook cactus, a barrel-shaped plant covered with hooked spines.

-- Ball cactus, a plant that grows and flowers easily indoors.

Both cacti and succulents prefer well-drained soils with low water-holding capacity. Sandy soil mixes are recommended. Special cacti soils can be easily prepared as long as all the ingredients are free of soil-borne diseases. A good starting mixture for desert plants might include equal parts of good garden soil, coarse builders sand and peat moss. Add one-half cup of bone meal to each 12 quarts of mixture to supply phosphorus. Planting is best in clay pots that allow the soil to dry out quickly between waterings.

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**Dr. Robert Nuss is a horticulturist at Penn State. He coordinates all extension horticulture programs. He has bachelor's, master's, and doctoral degrees in ornamental horticulture and has been on the Penn State faculty since 1966.