Fertilizing plants and watering them properly are closely interrelated. Plants obtain sufficient nourishment only when the soil is moist. This horticultural fact is often overlooked.
Many people refuse to believe that plants should be watered every day. They counter with the assertion, "Over watering kills your plants." This is true, but 99% of all container bound plants suffer from drought rather than from excess water.
There are two methods of watering plants; one entails the use of a sprinkling can, the other is automatic watering. If you have gone to all the trouble of mixing soil and installing lights, you will want to understand thoroughly the principles behind each system. You never can quite get away from a watering can, and yet for your tiny seedlings, vegetables, annuals, and perennials you will probably prefer to use automatic watering.
The philosophy of watering is well illustrated in terms of the out of doors. What gardeners call a "really good rain" does not just sprinkle the ground but saturates it thoroughly. It does not come down in a flood but falls gently for some time. Growing conditions are considered excellent when such a rain is followed by sunshine, so that the soil dries out gradually; but before it actually cakes and cracks, another good shower should come along. Try to give your plants these ideal conditions. A number of things will help.
The first important step is to purchase a good watering can. A skillful waterer is able to use anything from a tumbler to a pitcher but a watering can with a long spout is a great help. Many types are on the market. One type has a spout two feet long, which makes it possible to reach all your plants easily. The tips of these spouts vary in diameter from 1/8" to 1/4". The smaller the opening, the smaller the stream they deliver. This is excellent for your plants, provided you do not skimp on the amount of water you give them. Sometimes it seems to take a long time to moisten the soil in a pot thoroughly with a small stream of water.
How to Water
With your sprinkling device in hand and your thinking cap set firmly on your head, you are ready to water. Do not just draw the water from the tap, but test it as you do for a baby's bath by sticking your wrist in it. It must be just lukewarm-neither cold not hot. Study, too, the needs of your plants. For example, our African violets, in three inch pots, usually require about one-fourth of a cup of water apiece per day. The begonias, on the other hand, one whose leaves are about equal to all the leaves of the African violet, takes at least four or five cups a day.
When the soil in a pot looks dry, pour on about 3/8" of water; if it looks quite wet, add 1/8" to 1/4". Add the water slowly. When a small amount seeps through the drain hole at the bottom, the plant is properly watered. If, in the course of a minute or two, no water has penetrated through, add more. Make a practice of letting only a small amount come through the hole, since large amounts of water will carry away the nutriments in the soil. But make sure it does come through; oftentimes you may need to add water two or three times if the soil is dried out. When you have learned to judge the needs of each plant more accurately, only a very small amount of water will seep through the drain hole. That is the whole story of correct watering.
But life is complex. Even in this simple operation there are a number of traps. You may have skipped a day or two so that the soil is thoroughly dried out and shrinks away from the sides of the pot, leaving a space around the edge. As you pour water out of your sprinkling can, it will drench down the sides and come swiftly out the bottom, counterfeiting the real thing. If your thinking cap slips off, you can water your plants in this fashion and scarcely give them a drop to drink, as the the ball of earth is completely dried out and the water will not penetrate.
When the soil in the pot is dried out, it must be thoroughly soaked, pot and all. Submerge the pot in a pan of water so that the water comes nearly to the rim. Remove the pot a soon as the soil is moist. With your fingers press the soil back against the sides of the pot so the gap will be closed and you can water normally again.
You can achieve the same result-but it takes more care-by watering the plant from the top and pressing the soil firmly against the sides with the fingers. The soil, as it gets wet, swells. The process will to be repeated three or four times before the soil is thoroughly moist. The first method is usually safer for a beginner.
Sometimes the drain opening in the bottom of a flowerpot will become sealed off. This prevents the water from draining through, and the soil becomes waterlogged. You can detect that a pot is not draining when water remains for some time on the surface of the soil. Correct the difficulty immediately, for plants cannot live long in water. Drain holes occasionally become sealed off when pots rest on a very smooth surface. Usually there is sufficient dirt or unevenness on a bench to prevent this from happening; but if your have trouble with it, the pots may me set a a hardware cloth, pebbles, or a layer of vermiculite.
You can tell whether soil is too wet or too dry by touching the surface with your finger. Dry soil is firm, and very little will adhere to your finger. Moist soil is soft, and much more will adhere, leaving your finger somewhat soiled. Water-soaked soil is so wet the water will ooze out when you press it. This usually occurs when your flowerpot is placed within a decorative container. Should this happen, immediately empty the water from the decorative container and take pot and plant to the kitchen sink. Lay the pot on its side, and the excess water which has collected in the soil will drain off. It is probably best to leave the plant on its side for about a half-hour, because the roots of the plant will die if they are allowed to remain in water soaked soil. After draining off the water from a water-soaked plant, do not water it until the surface of the soil again has a normal appearance. Soil is always darker when wet; as you observe its color, you will gain experience in gauging the amounts of water needed.
When all is said and done, watering from the top is an art, and many fail to learn it. However, there are other ways of watering plants. Self-watering devices are not difficult to install, and the plants thrive with this method of watering.
We were slow to investigate automatic watering for soil pots because we ourselves had mastered the art of watering, but once we had used it we became enthusiastic devotees of the system and installed it wherever we could. Unlike many automatic devices, an automatic watering system is not difficult to provide and entails very little expense. We got our start in gardening through hydroponics, the ultimate automatic watering device, but moved on to soil because it was less costly and less finicky and you can farm more land than hydro pots. With these simple techniques, the plants grow much better because the soil is kept constantly moist and it saves you a lot of time, hours of time.
One of the simplest forms is the wick method. It is possible to purchase special flowerpots that are designed to be used with a wick, but it is an easy matter to adapt any container. Just as a lamp wick carries oil to the flame, such a wick carries water into the soil as the plant absorbs it.
Wicks may be made of stove door seals or asbestos rope, cylindrical fiberglass, or pieces of cotton cloth or burlap make into 1/4" cylindrical roll and held in place with string or rubber bands. About 1 1/2" inches of one end of the wick are frayed and unraveled and spread out in the bottom of the pot. The other end is threaded through the drain hole and rests in water. The pot is rested to keep it above the water. Empty tuna fish cans, well washed, with a hole punched in the center of the bottom for the wick to pass through, make excellent stands for pots in your decorative water container.
Your plants will grow much better as soon as adopt this method, for it ensures a constant water supply. Of course, you need to keep the water replenished. Washing and packing of the soil and nutriments are also eliminated.
Seedlings which are to be grown in flats can be watered with wicks too. Holes about four inches apart each way are drilled through the bottom of the flat, and wicks run through the holes into a pan underneath, which is filled with water. Watch the flat to make sure it does not dry our even slightly, but generally it will not if the reservoir below is kept supplied with water.
When it comes time to fertilize the plants that are being automatically watered, we water each pot separately with a watering can. A fairly safe rule is to add 1 cubic inch of the fertilizer solution to each 6-8 cubic inches of soil. Thus, a three inch flower pot or a 2" soil block requires 3 tablespoons of the fertilizer solution. A 4 inch pot or 3" soil block requires 1/3 cup of solution; a 5 inch pot, 1/2 cup, and a 6 inch pot or a 4" soil block, 3/4 cup.
If you are using automatic watering for seedlings that you plan to transplant out of doors, and they are in micro blocks, it is very easy to figure the number of cubic inches of soil, and to add the proper amount of fertilizer solution each week. Fertilize when the depth of water is low.
Installing automatic watering does not relieve you of the necessity of keeping a watchful eye on your plants to see that they do not dry out. Oftentimes, it will be necessary to water from the top. Cucumbers, melon, squash, and lettuce seedlings use a great deal of water and will probably need additional amounts.