November 1989

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Gardening for Profit

A Guide to the Successful Cultivation
of the Market and Family Garden


Peter Henderson

first published in 1866, reprinted from 1874 edition
Index to selections from Gardening for Profit

Chapter IX

The Uses and Management of Cold Frames

We use cold frames for preserving Cauliflower, Cabbage and Lettuce plants during the winter, and the forwarding of Lettuce and Cucumbers in spring and summer.

To make the matter as clear as possible, we will suppose that the market gardener, having five or six acres of land, has provided himself with 100 of 3 x 6 feet sashes. The Cauliflower, Cabbage, or Lettuce plants, which they are intended to cover in winter, should be sown in the open garden from the 10th to the 20th of September, and when of sufficient size, which they will be in about a month from the time of sowing, they must be replanted in the boxes or frames, to be covered by the sashes as winter advances.

The boxes or frames we use, are simply two boards, running parallel, and nailed to posts to secure them in line. The one for the back is ten or twelve inches wide, and that for the front seven or eight inches, to give the sashes, when placed upon them, pitch enough to carry off rain, and to better catch the sun's rays. The length of the frame or box may be regulated by the position in which it is placed; a convenient length is fifty or sixty feet, requiring eighteen or twenty sashes.

Shelter from the north-west is of great importance, and if the ground is not sheltered naturally, a board fence six feet in height is almost indispensable. The sashes should face south or south-east. Each sash will hold five hundred plants of Cabbage or Cauliflower, and about eight hundred of Lettuce. These numbers will determine the proper distance apart, for those who have not had experience. It should never be lost sight of, that these plants are almost hardy, and consequently will stand severe freezing without injury; but to insure this condition they must be treated as their nature demands; that is, that in cold weather, and even in clear winter days, when the thermometer marks 15 or 20 degrees in the shade, they must be abundantly aired, either by tilting up the sash at the back, or better still, when the day is mild, by stripping the sash clear off. By this hardening process, there is no necessity for any other covering but the sash. In our locality, we occasionally have the thermometer from 5 to 10 below zero for a day or two together, yet in all our time we have never used mats, shutters, or any covering except the glass, and I do not think we lose more than two per cent of our plants. some may think that the raising of plants in this manner must involve considerable trouble, but when they are informed that the Cabbage and Lettuce plants so raised and planted out in March or April, not unfrequently bring a thousand dollars per acre before the middle of July, giving us time to follow up with Celery for a second crop, it will be seen that the practise is not unprofitable.

But we have not yet done with the use of the sashes; to make them still available, spare boxes or frames must be made, in all respects similar to those in use for the Cabbage plants. These frames should be covered up during winter with straw or leaves in depth sufficient to keep the ground from freezing, so that they may be got at and be in condition to be planted with Lettuce by the end of February, or the first of March. By this time the weather is always mild enough to allow the sashes to be taken off from the Cabbage and Lettuce plants, and they are now transferred to the spare frames to cover and forward the Lettuce. Under each sash we plant fifty Lettuce plants, having the ground first well enriched by digging in about three inches of well rotted manure. The management of the Lettuce for heading is in all respects similar to that used in preserving the plants in winter; the only thing to be attended to, being to give abundance of air, and on the occasion of rain to remove the sashes entirely, so that the ground may receive a good soaking, which will tend to promote a more rapid and luxuriant growth.

The crop is fit for market in about six weeks from time of planting, which is always two or three weeks sooner than that from open ground. The average price of all planted is about $4 per hundred at wholesale, so that again, with little trouble, our crop gives us $2 per sash in six weeks.

I believe this second use of the sash is not practised outside of this district, most gardeners having the opinion that the winter plants of Caulilower, Cabbage, or Lettuce, would be injured by their complete exposure to the weather at as early a date as the first of March. In fact, here we have still a few old fogies among us, whose timidity or obstinacy in this matter prevents them from making this use of their sashes, which thereby causes them an annual loss of $2 per sash, and as some of them have over a thousand sashes, the loss is of some magnitude.

In my own practice, I have made my sashes do double duty in this way for fifteen years; the number when I first started being fifty, increasing to the present time, when I have in use fifteen hundred sashes. Yet in all that time I have only once got my plants (so exposed) injured, and then only a limited number, which I had neglected to sufficiently harden by airing.

We have still another use of the sashes to detail. Our Lettuce being cut out by middle of May, we then plant five or six seeds of the Improved white spine Cucumber, in the centre of each sash. At that season they come up at once, protected by the covering at night. The sashes are left on until the middle of June, when the crop begins to be sold. The management of the Cucumber crop, as regards airing, is hardly different from that of the Lettuce, except in its early stage of growth it requires to be kept warmer; being a tropical plant, it is very impatient of being chilled, but in warm days airing should never be neglected, as the concentration of the sun's rays on the glass would raise the temperature to an extent to injure, if not entirely destroy the crop. This third use of the sashes I have never yet made so profitable as the second, although always sufficiently so to make it well worth the labor.

There are a few men here who make a profitable business from the use of sashes only, having no ground except that occupied by the frames. In this way the winter crop of Cauliflower or Cabbage plants is sold at an average of $3 per sash, in March or April; the Lettuce at $2 per sash in May, and the Cucumbers at $1 per sash in June, making an average of $6 per sash for the season; and it must be remembered that these are wholesale prices, and that too, in the market of New York, where there is great competition. There is no doubt, that in hundreds of cities and towns of the Union, the same use of sashes would double or treble these results.

Cold frames are also used for sowing the seeds of Cabbage, Cauliflower, and Lettuce, instead of hot-beds; if the frames are closely shut up and covered at night by mats, the plants will be but little later than those from the hot-beds, and are raised with far less trouble. In sections of the country where these plants cannot be set out before May, it is useless to raise them in hot-beds. On the other hand, in the Southern States, where in the months of February and March there are no frosts, by adopting the same care in covering up at night, the seeds of Tomatoes, Peppers, and Egg plants, and the sprouts from Sweet Potatoes, can be forwarded with much less trouble in the cold frames than in the hot-bed.

I am sometimes asked the question, "How much freezing and thawing plants of Lettuce, Cabbages, etc., will stand without being destroyed." I have always taken the ground that the freezing and thawing, instead of being injurious, is a necessity for their safety. In doing so I know I run in direct opposition to a large majority of my brethren, but the experience of nearly a quarter of a century, yearly increasing in extent, confirms me that I am correct, and I am further assured in my opinion by knowing that there is not a market gardener in this vicinity but whose practice in the management of cold-frames is the same as my own, though if the question was asked some of them if thawing and freezing did not injure plants, the answer might be in the affirmative, so universally has the dogma been accepted.

Again: "How long can frozen plants be kept from the light under shutters?"—Much would depend on atmospheric conditions. If the temperature ranged at night from 25 to 32—merely sufficient to mildly freeze the plants— they might remain in good condition for four or five weeks, but if subjected to a zero atmosphere, without change, as many days might prove injurious. A very common practice with cold-frames in this vicinity is, if the plants are frozen in the frames previous to a snow storm we allow them to be covered up by the snow often for two or three weeks, provided that it is deep enough to protect the plants from severe frosts, as in that condition the plants, though excluded from light, are subjected only to a temperature of from probably 25 to 32, which simply keeps them dormant. But if, on the other hand, the plants are not frozen when snow covers the glass, it becomes necessary to remove the snow in three or four days after falling, else the plants will become blanched, and

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