Potting soil should also be in the right condition as to moisture. This is not easy to describe, but it must handle freely, and yet there should be no necessity for the immediate application of water after sowing seeds or planting bulbs. In the event of the compost being too dry, give it a soaking and allow it to rest for one or more days, according to the time of year and the state of the atmosphere.
Pots, new or old, should be soaked in water before use. They are very porous, and by absorbing moisture from the soil they may at once make it too dry, although in exactly the right condition before being placed in the pots. And old pots ought never to be used until they have been scrubbed quite clean. These may appear to be trivial matters, unworthy of attention. They have, however, an influence on the health of plants, and experienced growers know that a few apparent trifles make all the difference between success and failure. Pots which are dirty, or covered with green moss, prevent access of air, and tend to bring about a sickly growth. Cleanliness in horticulture is valuable for its own sake, and for the orderly routine it necessitates on the part of the cultivator.
Pots are known both by number and by size. They are sold by the ‘cast,’ and a cast always consists of the distinguishing number. The following are the numbers and sizes:—
| Number in Cast | Inches | |||
| 72 | Inside diameter | across top | 2-1/2 | |
| Small | 60 | ” | ” | 2-3/4 |
| Mid. | 60 | ” | ” | 3 |
| Large | 60 | ” | ” | 3-1/2 |
| Small | 54 | ” | ” | 4 |
| Large | 54 | ” | ” | 4-1/4 |
| Small | 48 | ” | ” | 4-3/4 |
| Large | 48 | ” | ” | 5 |
| 40 | ” | ” | 5-1/2 | |
| 32 | ” | ” | 6-1/4 | |
| 28 | ” | ” | 7 | |
| 24 | ” | ” | 7-1/2 | |
| 16 | ” | ” | 8-1/2 | |
| 12 | ” | ” | 9-1/2 | |
| 8 | ” | ” | 11 | |
| 6 | ” | ” | 12-1/2 | |
| 4 | ” | ” | 14 | |
| 2 | ” | ” | 15-1/2 | |
| 1 | ” | ” | 18 |
Watering is sometimes conducted on the principle that the usual time has arrived, and therefore the plants must have water. But do they need it? Press the fingers firmly on the surface; if particles of soil adhere it is too dry. Or tap the pots smartly with the knuckles or with a stick, when a clear and unmistakable answer will be obtained. Plants differ widely in their demand for water. Some are very thirsty, others require less frequent attention. The season of the year and the state of the atmosphere have also to be considered, as well as the fact that a heavy soil is more retentive of moisture than a lighter compost. A watchful eye and a willing hand will seldom err on this point. The water should always be of the same temperature as the house, otherwise the plants will be constantly checked. A tank in the greenhouse meets this requirement. In its absence, the watering-pots should be kept full under the stage, and they will be ready when wanted.
In the open ground, it is better to water a few plots thoroughly for two or three successive evenings, and then have an interval, rather than moisten the surface daily. The effect of constantly applying small quantities of water is to encourage the surface growth of roots. Then, if the sun shines fiercely on the soil, the first day of neglect results in immense mischief.
Drainage is easily managed. Into each pot put a crock almost the size of the bottom, with the convex side upwards. There need be no niggling to remove sharp angles, or to make the fragment shapely. Cover this with smaller crocks, and these with moss, or in some cases with small pieces of charcoal. If the compost has a proper admixture of sharp sand or grit, free drainage will be insured, and yet the soil cannot be washed through the pot. Silver sand is often employed, and there is nothing better for the purpose. But the sweepings from gravel walks, finely sifted, may be substituted. Road grit is often infested with weed seeds.
Ventilation is important, for a house full of plants cannot long be kept closed with impunity. The lights should be opened whenever the state of the weather may permit, and by doing this on the side opposite to the quarter whence the wind blows it is frequently safe to give air when it may be dangerous from other points of the compass; and it should be done early in the day, before the sun gets hot. Often the lights remain closed on a sunny morning until the atmosphere becomes stifling; and then perhaps plants which have been made sensitive by excess of heat are subjected to a killing draught.
In managing Temperature, there should be no violent alternations of heat and cold, for these bring speedy disaster; and, it is unwise to employ more heat than is actually necessary. Deviations from this rule are generally traceable to neglect. If the proper season for sowing seed of some important flower has been allowed to pass, an attempt is made to compensate for lost time by hurrying the growth in a forcing temperature. Every needless degree of heat will be harmful, and result in attenuated growth, poverty of colour, or in the attack of some insect plague which the weakly plant seldom invites in vain. It is wise always to employ the lowest temperature in which plants will flourish. This necessitates the proper time for their full development, and will result in a sturdy growth capable of yielding a bountiful display of bloom. Occasionally it is requisite to force some special subject, such as bulbs for Christmas festivities. Even then it is advisable to augment the temperature very gradually, and to defer the employment of its highest power until the latest possible moment.
Plants are frequently taken straight from the forcing pit into a cold room, to their utter ruin. A moment’s reflection will show the folly of such a proceeding. They should be prepared for the change by gradual transfer through lower temperatures; and if only a few hours are occupied in the process it will help them to pass the ordeal with less injury.