The other method is to construct the frames on the ground before severe freezing, and in this case the front should be at least twenty-four inches high, part of which--not more than half--may be below the ground level. The 2 x 12 inch planks, when used, are handled as follows: stakes are driven in to support the back plank some two or three inches above the ground,--which should, of course, be level. The front plank is sunk two or three inches into the ground and held upright by stakes on the outside, nailed on. Remove enough dirt from inside the frame to bank up the planks about halfway on the outside. When this banking has frozen to a depth of two or three inches, cover with rough manure or litter to keep frost from striking through. The manure for heating should be prepared as above and put in to the depth of a foot, trodden down, first removing four to six inches of soil to be put back on top of the manure,--a cord of the latter, in this case, serving seven sashes. The vegetables to be grown, and the season and climate, will determine the depth of manure required--it will be from one to two feet,--the latter depth seldom being necessary.
It must not be overlooked that this manure, when spent for heating purposes, is still as good as ever to enrich the garden, so that the expense of putting it in and removing it from the frames is all that you can fairly charge up against your experiment with hotbeds, if you are interested to know whether they really pay.
The exposure for the hotbeds should be where the sun will strike most directly and where they will be sheltered from the north. Put up a fence of rough boards, five or six feet high, or place the frames south of some building.
The coldframe is constructed practically as in the hotbed, except that if manure is used at all it is for the purpose of enriching the soil where lettuce, radishes, cucumbers or other crops are to be grown to maturity in it.
All this may seem like a lot of trouble to go for such a small thing as a packet of seed. In reality it is not nearly so much trouble as it sounds, and then, too, this is for the first season only. You will have a well built frame lasting for years--forever, if you want to take a little more time and make it of concrete instead of boards.