Conditions for indoor plants
Few rooms ideal
By nature, plants are denizens of the out-of-doors, the conditions of which are greatly modified inside a house. Out-of-doors a plant has 360 degrees of exposure-in other words, light and air from every direction. Indoors the light must come from a window, and whether facing north, south, east, or west depends upon the good fortune of the householder. And the farther we move from nature, from the country or suburban house to the apartment in the great, crowded city, the fewer the exposures are likely to be.
Indeed, it may astonish rural dwellers to know, in times of normal housing availability, the quest for cross ventilation is one of the chief influences in selecting a big-city apartment.
In the open, under good conditions, plants have not only the light they desire but the moisture they want when they want it, free circulation of air and temperatures to which they are adaptable. Indoors, the amount of humidity healthful for a plant well may rot, warp, or mildew the furniture or furnishings. Indoors a temperature suitable for the plants may mean acute discomfort for humans. Indoors the air may be stuffy or drafty, rather than freely circulating. Indoors, particularly in large cities, soil is scarce and expensive.
Wise selection vital
Even in the most unfavorable indoor conditions, some plants will succeed and the desire to make use of them is almost universal. Obviously the most practical path toward success with house plants is to select only those plants that can make moderate adjustments to the conditions which exist and to provide for them the cultural attentions which promote their development.
Major factor: sunlight
Especially for flowering plants, sunlight is a major consideration. A north window usually gives good clear light but practically no sunlight except for a brief period of midsummer. East windows bring in the morning sun, west windows admit afternoon sunlight. South windows bring in sunlight for the longest period of all, the sun in this hemisphere being in the southern horizon.
The best window
Consequently it would be illogical to put flowering plants in the north window except when the indoor gardener has resigned himself to discarding them as soon as they have begun to fade; but foliage plants or those which go through the winter in a semi-dormant state may well be placed there. By the same token, it would be unwise to take up the sunny space which flowering plants might occupy by placing winter-inactive foliage plants in a south window.
Fortunately, in using window areas for house plants, there are practical means by which the cold air from an open window or the excessive heat from radiators, which are frequently placed in front of windows, may be combatted. A water pan, placed on top of the radiator, increases the humidity as it evaporates. And a shelf or stand for the plant containers, built higher than the level of the sills, permits the window to be opened a bit without the air hitting the plants directly.
Window stands for indoor plants
It is highly advisable to have a metal liner for the shelf or stand. This watertight pan makes it possible to give the plants an occasional soaking from the base. It also provides a serviceable place into which the plant containers may drain, and enables the indoor gardener to place peat moss about the containers, increasing the moisture of the situation.
Soil for indoor plants
Ideally, the soil for house plants would be, in volume, about 3/4 loam and 1/4 animal manure, thoroughly mixed with all organic matter completely disintegrated. Addition of sand will thin out heavy soil to suitable texture. The indoor gardener, however, may very well be unable to achieve this soil ideal. To approximate it he may start off with a foundation of rich, loamy garden soil, adding organic matter such as decaying leaves, grass, and weeds in place of manure. Some of the commercial plant foods or a small quantity of bonemeal may be added from time to time to maintain fertility. In an apartment or small home where there is no ready supply of humus, plants are helped by a mulch of tea leaves, taken right from the kettle.
If the indoor gardener is doing his own potting, his plants should be well established in pots before the season arrives for moving them indoors. The bottom of the pot should contain gravel, cinders, or broken pieces of other pots to provide drainage. The surface of the soil should be at least 1/2 inch below the rim of the container so that it will not overflow when watered. The pots should be of the smallest size that will hold the roots properly, and should be cleaned properly.
Frequently when a plant begins to fade, it may have become potbound, that is, its roots may have shoved right out to the wall of the pot. This means that in their quest for nourishment the roots have used up the soil, and the plant must be repotted. Ferns, however, do not seem to do well until they have become potbound, and they would rather be fed than transferred.
Watering indoor plants
The best general rule for watering potted plants is to give the soil the hand test previously prescribed to determine whether the garden's earth is ready to be worked. Clasp a handful of soil; if, when released, it hangs together, it does not need watering, but if it falls apart, soak it thoroughly. Be sure in watering a house plant that you do not wash the soil away from the crown or get the moisture into the crown. And do not let the roots stand in water; as soon as the soil seems to be saturated put the pot where excess moisture can drain off.
During the summer many of the plants grown in the house may be sustained simply by burying the entire pot, right up to the rim, in the ground in a partially shaded spot. House plants also may be used for decoration of outdoor situations, such as porches and terraces, depending on the amount of sunlight they can stand.
Indoor plant sicknesses
Most of the ailments of house plants are attributable to the artificial conditions in which they must grow and to incorrect cultural practices. If the plant loses all its leaves, gas poisoning, a switch from strong sunlight to darkness, shock of transplanting, or sudden temperature change may be the cause. There is strong evidence of gas poisoning if, after defoliation, the shoots remain dwarfed, branch, and grow undersized leaves. If the leaves lose their normal color, excessive watering, undernourishment, or attacks by certain insects are indicated. Unaccustomed exposure to direct sunlight, causing burning, and excessive watering can result in spotted foliage. Cold drafts, poor watering, and insect attacks are causes of browning of leaf tips.
Fungus leaf spots sometimes attack such house plants as pandanus and rubber plants. This is usually a secondary ailment, to be avoided by maintenance of good growing conditions and cultural attention. Leaves so attacked should be destroyed and all plant debris removed from the pot.
Indoor insect enemies
The principal insects attacking house plants are spider mites, plant lice, mealybugs, scale insects, and occasionally worms at the roots.
Mealybugs are tiny white tufts which gather in masses usually along the stems, in leaf axils, and on the veins on the under sides of leaves. A bath of soapsuds or a solution of 2 level tablespoons of soapflakes, and 1 1/2 teaspoonfuls of nicotine sulphate in a gallon of water used as a spray or bath are helpful in combatting mealybugs. Careful examination of the plants and diligent treatment must be repeated until the pests are dislodged.
The same soapsuds or soap and nicotine preparations may be used to combat scale insects, which live under hard, round or oval scales and arc difficult to dislodge. They most frequently attack citrus, crotons, ferns, ivy, oleander, palms, and rubber plants.
Spider mites, red or green insects so tiny they can scarcely be seen, gather in small webs spun in at the junction of the leaf and the stem. Soapsuds baths, pressure spraying with plain water, or syringing with contact insecticides such as derris extract are recommended.
White flies, when young, are light green and scalelike in appearance; as adults they are covered with a powdery white substance. Tiny in size, their attack causes leaves to yellow and die, and they also excrete a substance on which grows a fungus that blackens plants. Combat them with sprays, several times a week, of nicotine sulphate and soap solution or derris.
Plant lice, which are black, brown, or green, are sucking insects. They infect young stems or the nether side of a leaf, causing it to curl. Pyrethrum or derris spray, nicotine sulphate and soap solution, or soapsuds bath are used against them.
Tiny white worms that eventually take to the air as small flies called fungus gnats frequently injure plant roots. Soak the soil with a corrosive sublimate solution of a pint of water in which a 7 1/2 grain tablet of bichloride of mercury is dissolved. Bichloride of mercury is highly poisonous.