Caring for Houseplants
Most houseplants need to be watered only when the soil feels slightly dry, They then should be watered thoroughly. But plants should never be watered slavishly (once a day or once a week) because moisture requirements change with the seasons. Pots holding plants having a natural preference for evenly moist soil should be kept on wet pebbles, so that there is always a moisture reserve. Such plants can be bottom watered in the morning as long as the waterline recedes below the pebble surface by afternoon. Only bog plants or water plants will thrive in pots that remain in water.
Plants in an open terrarium need infrequent watering and are watered only when the soil appears light brown through the glass sides of the terrarium. Plants in a closed terrarium seldom need any water, since moisture cannot escape.
Houseplants should always be watered with tepid water, because cold water injures tropicals. Daily use of a fog sprayer is' very helpful in replenishing air moisture, and an occasional spray bath removes harmful soot and dust. For hairy leaved plants, a camel's-hair brush dipped in water should be used.
The chief danger in caring for cacti and other succulents is overwatering. They should be watered very sparingly in winter. In summer, however, they should be watered whenever the soil becomes bone-dry. Cacti in tiny pots may need water two or three times a week.
Any potted plant with its roots confined in a small volume of soil drained of nutrients by frequent watering is especially dependent on fertilizer. Either a chemical or an organic fertilizer may be used as long as it is water-soluble.
A general-purpose fertilizer may be used for all plants except those requiring an acid fertilizer. Generally, the label directions should be followed carefully. When fortnightly applications are recommended, this refers to the season of active growth. In winter, when plants are more or less dormant, they should not be fertilized so often. It is also important never to fertilize a plant when the soil is very dry. Fertilizers such as bone meal and dried cow manure can also be mixed with potting soil.
Temperature and Ventilation
It is wise to keep a thermometer near plants as a guide in regulating temperature. A drop of 100 to 15° at night is good if the temperature does not go below 50° F (10° C), or 60° F (16° C) for the more tender plants. On very cold nights plants should either be moved back from window glass, or protected by a sheet of insulating material. Providing ventilation can be risky in winter, but since an occasional airing is needed, a window should be opened briefly on milder days, either in an adjoining room or where no draft will hit the plants.
One of the most neglected aspects of houseplant culture is pruning, because many people are hesitant to cut plants. However, a little commonsense pruning and pinching back can make the difference between weak spindly plants and vigorous stocky ones. Sharp pruners, which cut cleanly, should be used, and all cuts should be made just above leaf axils.