HOTBEDS AND COLD-FRAMES

In order to have vegetables early in the season it will be necessary to give them a start some weeks before the ground is in proper condition for the reception of seed. Sometimes this is done by sowing the seed in pots and boxes in the living-room, as advised in Chapter VI, but here conditions are not very favorable to healthy growth, unless great care is taken to follow the directions given in the chapter mentioned, and even then success does not always attend our efforts.

In order to give our plants the early start that they must have if we want vegetables at a time when most gardeners are getting the garden ready for planting, we must make use of the hotbed. If this is done we can gain from six weeks to two months in time, and have lettuce and radishes before our neighbors who are without hotbed facilities consider it safe to put seed into the ground.

At the North the first of March is quite early enough to get the hotbed under way.

I am aware that many young gardeners have the impression that a hotbed is, in some respects, a mysterious thing, and because of this they do not undertake to make one. Now there is nothing simpler than a hotbed when you come to a study of it. It is simply making a place in which summer conditions can be imitated by supplying it with steady, gentle heat, and in confining this heat within an inclosure. The heat is generated by the use of material which ferments, and the inclosure is nothing but a combination of boards and glass so arranged that the temperature inside it can be regulated to suit the requirements of the plants you undertake to grow in it.

The heat-generating material is generally fresh manure from the horse-stable, or a mixture of that and coarse litter.

Because the heat from rapid fermentation is quite intense, at first the material from which it is obtained should be prepared before the hotbed is brought into use. A quantity of it should be spread on the site selected for the hotbed—which should be one that is high and dry—covering a space larger than the hotbed frame is to be. Spread it in layers four or five inches deep, tramping each layer down well. When there is a foot and a half of it, cover it with something that will shed rain, and wait for fermentation to take place. A warm moisture will rise from it like steam. After two or three days fork the material over, and remove all straw, and make another heap similar to the first one, taking great pains to have it firm and compact. It is very important that it should have considerable solidity, as a heap of loose litter will never give satisfactory results. There should be at least a foot and a half of this heat-generating material.

While waiting for fermentation to take place in the manure-pile, prepare the frame for your hotbed.

Let it be about a foot and a half in depth at the back, and eight or ten inches deep in front, with sides that slope from the wider boards to the narrower ones. Cover it with glass set in sash. If possible have the sash hinged to the back-board, so that it can be lifted for ventilation without removing it.

The best location for a hotbed is one facing the south, that all possible advantage can be taken of sunshine, and against a building or fence that will protect it on the north from cold winds. Some persons prefer to make an excavation a foot or more in depth for the reception of the heating material, but this is not a matter of much importance. As a general thing it will not be possible to do this in a satisfactory manner while there is frost in the ground, as there will be at the North until after the first of March.

When the first stages of fermentation are over, set the hotbed frame in place, and fill in with five or six inches of very fine, rich soil. This is what your seed is to be planted in.

The young gardener will be surprised at the amount of heat contained in an inclosure like the one described. It will be very similar to the weather conditions of early or middle May out of doors. In it plants will grow healthily and vigorously, provided they are given plenty of fresh air. This is a matter of the greatest importance. Unless your seedlings are aired daily, if the weather is pleasant, they will make a rapid but weak growth, and when the time comes to put them in the cold-frame or the open ground—provided they are alive then—they will be so lacking in vitality that the change will be pretty sure to put an end to them. On every sunny or warm day the sash should be lifted an inch or two, about ten o'clock, and left in that condition until about two. Care must be taken, however, to see that the wind does not blow from a quarter that will drive the cold air in upon the plants. The admission of a cold blast will often be fatal to the tender plants.

Great caution must be exercised in regard to ventilation. The aim should be, at all times, to admit pure, fresh air without allowing cold to enter with it. This may seem a somewhat paradoxical statement, for at first thought it will seem impossible for air from without to come in without taking along with it the cold air which is in circulation outside, but when one takes into consideration the fact that the warm air inside the hotbed meets the air from out of doors at the point of entrance it will be understood that it repels or counteracts it to an extent that makes it safe to open the sash slightly when the outside temperature is nearly down to freezing-point. The hotbed-owner must study existing conditions and be governed accordingly. It is impossible to lay down any hard-and-fast rules to apply in this case.

On cold nights the hotbed sash should be covered with blankets or old carpeting to prevent the formation of frost on the glass. If you find, in the morning, that the glass is covered with moisture on its under side, raise the sash a trifle and leave it so until the moisture clears away.

If at any time you have reason to think that the warmth inside the frame is decreasing too rapidly, bank up about it with fresh fermenting material.

After constructing the hotbed and putting the frame and sash in place, test the heat inside by an accurate thermometer before venturing to sow any seed. When it registers 85° or 90° the bed is ready for seeding.

In making the frame for a hotbed care should be taken to see that all joints fit snugly. A great deal of cold can be admitted through a very small crevice. A few cracks will let out the heat faster than it is generated, therefore see to it that in constructing the frame a good piece of work is done.

Some persons tell me that they always bank up a hotbed with earth. This enables it to retain the heat better than it is possible for it to do without banking.

A hotbed will be of no particular benefit unless supplemented by a cold-frame. This is simply a snug inclosure of boards covered with glass, into which plants from the hotbed are to be set for the purpose of hardening them off before they are put into the open ground. In other words, it is a hotbed without heat. The temperature in it ought to register from 60° to 65°. Raise the sash an inch or two on sunny days before the rays of the sun striking on the glass raise the temperature inside to a degree too intense for the good of your plants.

It will be readily understood from what I have said above that in order to attain success in the management of a hotbed great care will have to be exercised at all times and frequent attention given. It is not a self-regulating thing by any means. You will have to consider the weather, the time of day when ventilation should be given, frequency of watering, and other matters which cannot be touched on here because of a more or less local character.

Plants in the hotbed should be watered cautiously. An over-supply will often cause the seedlings to "damp off," and a lack of sufficient moisture at the roots will speedily result in injury, if not death. Whenever water is applied, use a sprinkler that throws a fine spray. If thrown on the soil in a stream the water will often wash the smaller plants out of place. It may puzzle one to tell when just enough has been given. This is best determined by an examination of the soil. If moderately moist there is plenty of moisture below.