As a general rule, most potted plants can and should be watered from above. The main exception to this rule is the African Violet, because, as we pointed out earlier, wetting the leaves can be harmful to the foliage, and it is difficult to give them a good soaking without letting a little water splash on them. In almost all other cases, however, top watering is the most successful practice. Be sure that the pot is never filled with soil higher than an inch from the top. The best way to give the plant the soaking it needs is to fill it to the brim and let the water soak down through the roots until the excess flows out through the drainage hole at the bottom.
With those plants which like bottom watering, the procedure is just the reverse. Pour water into the dish in which the pot is standing, and let it soak up through the earth until the soil at the top is damp to the touch. Then you’re sure that the soil is wet through. Never let water stand in the dish after the plant has received a thorough watering. This will eventually soak the bottom of the roots and damage the plant. You have to be especially careful of this with any plants which you keep in a jardiniere. An hour or so after watering lift the pot from the container and check to see that there is no excess water left standing.
A variation of the system of bottom watering is wick watering. This compartively new system utilizes a thick braided wick, such as those used in oil lamps, to conduct water to the roots of the pot. You can buy pots specially designed for this purpose in your garden supply store. They consist of a covered saucer, on which the pot stands, which is filled with water. The wick is trained from the saucer through the drainage hole and spread on the bottom of the pot. As the soil dries out, water gradually soaks up through the wick and is distributed to the soil.
AIways use water as room temperature, or a little warmer. Cold water often has a tendency to blight many plants and is to be avoided for that reason. If you live in an area where the tap water is considered “hard,” it’s a good idea to use one of the commercial water softeners. In their natural state, your plants are used to rain water, the “softest” water you can find, and an excess of minerals in the water tends to stain the leaves and in some cases inhibit the growth of your plants.
At the risk of repetition, then, there are three things you should remember when it comes to watering your house plants: 1) Water when the soil feels dry to the touch. 2) When you water, soak the plants well, don’t use the system of a little often. 3)Use water at room temperature or a little above, not cold.