“How often shall I water or feed my house plant?” is the question most often asked by beginning indoor gardeners. The correct answer, “That depends…” is not so satisfying as a rule-of-thumb reply like “once a week” might be, but it’s the only accurate advice that can be given for house plants.
For example, your home in winter may be almost as arid as a desert. If so, your plants will need more water than during warm, humid summer weather. Likewise, plants in small pots probably will need watering more often than those in large pots, the smaller pot dries out faster. But, while a plant in bloom needs more water than it does at other times, in general, variations in water needs from plant to plant aren’t great. Except for cactus and succulents, most plants grow best in soil that is constantly moist _not wet.
A good rule: water whenever the topsoil feels dry, whether daily or weekly. Also, water thoroughly, so to supply enough water to moisten the soil all the way to the bottom.
If you water from the top, be sure to have broken potsherds, pebbles, or other loose material at the bottom of the pot for good drainage. This is not necessary for bottom watering. Instead, insert a wick (preferably one of fiber glass) to absorb water from a dish below, keeping soil moist.
Whether you water from top or bottom, it’s good practice to give plants an occasional ‘dunking’. Place the pot in a pail, or in your kitchen sink filled so that the pot will be half submerged. When the surface of the soil is moist, set the plant aside and allow the surplus water to drain away. Then return the plant to its usual location. (In the process, it’s a good idea to syringe the foliage and remove dust at the same time.)
However, don’t leave the pot standing in water more than an hour. Too much water over a long period prevents oxygen from get ting to the roots, roots must have oxygen.
For most plants (succulents and cactus are exceptions) it’s almost impossible to over- water if you’ve provided adequate drainage.
A common mistake made by amateur indoor gardeners is overfertilizing. A little plant food goes a long way, too much can burn the roots and actually kill a plant. This is especially important to watch, for the various brands of fertilizers on the market differ in strength. So it pays to follow package directions exactly.
How much food you give your plants is also influenced by the seasons of the year. While older plants benefit from a light feeding every few weeks, during winter it is best to stop feeding them except those that bloom during this period. Most of the foliage plants grown as house plants go into a reduced growth period during colder months, and giving them fertilizer disturbs their natural growth habits. You should also guard against fertilizing new plants obtained from your florist. They need no fertilizer for the first six weeks after you buy them _in fact, feeding these plants may be harmful to them.
Commercial fertilizers always indicate on the package the proportions of nutrients they contain. Those usually present are nitrogen, phosphoric acid, and potash, generally represented on packages and in the order stated by the ratio figures.
In your eagerness to help your plants along, you may overdo your feeding. It’s not wise to assume that any sickly looking plant will benefit from a dose of plant food. The plant is more apt to be ailing because of too little light, too much or too little water, too dry an atmosphere, or poor quality of potting soil.
If your plant is suffering from starvation, nitrogen is most likely to be what it lacks. Symptoms are a yellow color in new leaves, and lack of vigor in new growth.
While symptoms of injury from gas fumes, too much water and too little light are similar, when one of these is the culprit you usually find lower leaves turning yellow, while those higher up stay green.
Plant foods come in powdered, granulated, tablet, and liquid form. Experiment with all kinds, following suggestions below, to see which plant food you prefer.
When using dry food, be careful not to get it on the plant, and to water into the soil at once. Tablets may be inserted in the soil at the outer edge of pot. These are absorbed in the course of several waterings.