What we call a coldframe (low walls of wood or brick supporting some glazed sash) is a miniature greenhouse without any artificial heat. Every grower should know the great value of them and how much they add to his capacity for raising many plants and temporarily increase the area of his glass. There are times, especially with the man who raises bedding plants, when his place is fearfully congested and the addition of another thousand feet of bench room is the greatest relief.
Coldframes are used for many purposes. In the fall and winter for pan-sies, to store away hybrid perpetual roses, to winter pot carnations that are wanted for next summer's bloom, to winter many herbaceous plants that have been raised from seed the previous August, to protect Roman hyacinths, and also the Dutch hyacinths are as well under glass, where they don't get so wet, and the severe frost does not crack the pots.
Some of our common little vase plants we winter in coldframes, viz.: the sed-ums, lysimachia (money vine) and the variegated glechoma. In the spring these frames are of still greater use; not only do they relieve our crowded benches, but many plants do far better in them than in a greenhouse. In the frames you have perfect light, an abundance of air, and on fine, warm days the sashes can be removed, when full exposure to sunlight and air can be given.
Carnation growers can put their young plants into the coldframes the first part of April and a few weeks in them will condition the plants for the open field much better than a lofty hothouse. By the middle of April all the annuals in flats or planted can go into the cold-frames, and many of our bedding plants will be greatly benefited by a few weeks in the coldframes. It is a far better place for geraniums than a shaded house without fire heat.
In the summer, without the sash, we find great use for the frames for plunging out our azaleas, acacias, hardy roses in pots, and many plants that are kept in pots during summer. Boards fastened up to keep your plunging material in place may do as well, but the frame is all ready to hand.
I had forgotten one very important use, and that is for the longiflorum lilies in the fall. Both the Bermuda and the Japan grown are potted and placed in the coldframes, and in case of very heavy rains are much better covered with the sash. Those you keep for Easter and later flowering must be kept in the frame till December or later, and there is where your coldframe will come in right; in fact, it is a necessity.
The ground on which these frames are stood should never be in a place where surface water will stand, even if only during heavy rains. If it is not a naturally dry position make provision to carry off the rains from the surrounding surface. Where a large lot of sash is used for this purpose some of the frames at least can be permanent. By that I mean they can be built of cedar or cypress posts (4x4 is a good size) driven into the ground every eight feet for the back and front line of the frame, which can be any desired length. I have one of thirty sash in length devoted to violets. Where they are built to fixed posts in this way it is best to use 2-inch plank for the walls. Where the frame is movable and is made in length to fit three or four sash, 1-inch lumber will do. The sashes are made of various sizes, but it is wrong to have them an awkward size; six feet long by three feet six inches wide is large enough, and some prefer three feet wide.
For a great majority of our frames, whether permanent or portable, the height at back is eighteen inches and the front twelve inches, giving the sash a slope of six inches to the sun; that is plenty. For a few larger plants we have some frames that are two feet at back and eighteen inches in front. I prefer the cypress sash, butting the glass. Always use double thick glass; these sash get a good deal of handling and occasionally one blows off in a gale. They run risks of breakage far more than a fixed roof; they are moved repeatedly to ventilate and are raised to enable you to water, so the double thick glass will save the extra price of glass in one year.
Always have a rafter for every sash to rest on and slide on. They are very simply made by nailing a piece of pine 2x1 on to another piece of pine 4x1, and have a hook and eye for every sash, to keep them from blowing off in a storm.
There are always enough spare sash in the dark winter days so that you can overhaul the whole lot, mend them where needed and give them a coat of paint. And then when you put on the sash over a young batch of carnations there won't be a glass out in each sash, which you often see decorated with a piece of board, and which blows off to make a hole in the next sash, to chill or drown out the plants beneath, to disseminate profanity and vex all around. Some men may take all the little accidents that ensue from neglect quite placidly, but depend upon it when they do they are sluggish, good natured fellows that won't get far ahead.
A hail storm that knocks out all your glass is no cause to get irritable. The writer has been through it and knows how it feels. It can't be helped, no power could hinder it, and therefore you should be cheerful and clean up and find out the best place to buy glass as quick as possible. But these so-called accidents which are purely neglect are what vex a man.
A good part of your frames should be made to take four sash, because they are what are used on the hotbeds. You seldom need those deeper than eighteen inches by one foot and the ends should be fastened to a 2x4 post in the four corners. All sashes should have a strip of iron running across the middle on the under side, to which each bar should be fastened with a screw. It helps greatly to strengthen the sash and keep it from winding. The strip of iron can be 3/4 X1/4 inch. In summer, when of little use, see that the sashes are laid or stood on timbers, off the ground, not winding, and that a door or some such thing be stood up and tacked to the last one covering the glass, so that your sons or sons' friends, when showing you how they can curve a ball, will be satisfied to break the windows in your barn and not go through three or four depths of sash.