If there is any one thing about amateur floriculture more earnestly advocated and urged by writers on plant-growing than drainage, and more systematically ignored by the parties to whom the advice is given, I do not know what it is.
It seems difficult to convince amateur gardeners that drainage is a matter of prime importance. "A whim," some of them call it. Others speak of it as a "pet theory." Xow it is neither a whim nor a theory.
On many farms one finds low places where not much but bushes and semi-aquatic plants growT. Farmers clear off these places, and attempt to make grass grow there, but their attempts generally result in failure. Something is wrong with the soil.
But when the farmer under-drains these marshy places by the use of tile, which allows the excess water to drain out of the soil above, and run away, speedily a great change takes place. The land that was sour and soggy because always saturated with water, soon becomes workable, and, after a little it will grow good crops. Why this change ? The explanation is very simple: Water, which had been retained until it had made the soil unfit for use, passes off, and air enters to fill the vacancy left by the water, and the cold, heavy, sour soil is warmer, lightened, and sweetened. "Reclaiming the land" is the term the farmer uses for this process, and it is a good one, for really the land which was wholly useless because it had been neglected is reclaimed and often made more valuable than other portions of the farm.
Now drainage in plant-growing is to plants in pots precisely what under-draining is to the swampy places on the farm. By it all excess water is allowed to settle to the bottom of the pot from the soil above, only enough being retained by it to meet the immediate needs of the plant growing in it. A soil so drained will remain sweet and in a healthy condition indefinitely, and plants will flourish in it as satisfactorily as in the garden beds. But stop up the hole in the bottom of the pot, and allow surplus water to collect until it floods the soil above, and straightway you have trouble with your plants. None but aquatics or semi-aquatics can long survive their roots in mud.
I have explained the principle of drainage at some length because I want to impress upon the mind of the reader the absolute necessity of giving careful attention to this matter if he or she desires to grow good plants. Every pot more than four inches across, and less than six, ought to have an inch of drainage below the soil in it, and pots larger than six inches, and from that size to ten inches should be provided with an inch and a half or two inches of it.
This material may be of any substance that is not readily affected by water. Broken pottery, brick, gravel, charcoal-all these are good. Break them into pieces about the size of a chestnut. Place some of the larger pieces about the hole in the bottom of the pot in such a manner that they will neither fall into it, or allow others to, and fill in about them with smaller pieces to the necessary depth. Some advise placing something flat over the hole in the pot, but I do not, for if any of the soil washes down it will settle and close the opening about the piece, and the first thing you know your soil will be like mud, because there is no chance for the water to escape. Always plan to keep this hole free from obstructions. It is a good practice to turn bottom side up, occasionally, and make sure, by the finger, or a stick, that this hole is not clogged up.
In order to prevent the soil from washing down and filling the crevices in the drainage, a layer of sphagnum moss should be spread over it before any soil is put into the pot. This is important. If moss can not be obtained, use a thin piece of sod, grass-side down. Moss, however, is much preferable, as it does not easily decay under the action of water.