How to Build a Cold Frame and Hotbed

Learn how to build a hotbed for your winter gardening needs.

| March/April 1976

Any listing of inspirations for MOTHER EARTH NEWS  just has to include mention of the work done over the years by J.I. Rodale, his son Bob, and the other fine folks at the Rodale organization in Emmaus, Pennsylvania.

Thanks to (I believe) my Uncle Charles, who used to exchange ideas on wholistic agriculture with Louis Bromfield. My father received some of the very first issues of Organic Gardening magazine that were ever printed. And the ideas therein — with others of our own — were what we used to rebuild "one of the most worthless farms in the continental United States" into one of the best back there in the 1940's. 

Well, few of you folks reading this MOTHER have a 144-acre farm to restore, but almost anyone perusing this issue can (or should be able to) use the straight skinny on building cold frames and hotbeds. So here 'tis. Direct from Rodale Press. — JS.

What is the difference between a hotbed and a cold frame? If you want to grow peppers, tomatoes, eggplants, or any of the other heat-loving plants, a hotbed is best to grow them in., A cold frame has the same construction as a hotbed, except that there is no heat used inside it. In a cold frame you can propagate such cold-loving plants as cabbage, the broccoli family, cauliflower. Or you can use your cold frames to taper off and harden plants that have been moved into them from the hotbeds, to get them hardened between the hotbed and setting out into open garden or field.

There are two types of hotbeds. One is heated by a great deal of fermenting straw or fresh manures (preferably horse or chicken) which has been placed in a pit two and one-half feet deep. The manure is packed down to a depth of 18 inches, well watered to soak. Then you shovel into the pit 5 to 6 inches of composted soil or good rich topsoil. This soil — which will make the seedbed — must be sieved fine.

Manure Hotbeds

The making of a manure hotbed is described by New Mexico extension horticulturists as follows:

The first essential in preparing a manure hotbed is to have fresh horse manure, preferably from grain fed animals. The manure should contain one-third straw or other similar litter. Sometimes there is insufficient straw in the manure for proper heating. If it does not have sufficient straw in the manure it may not ferment or, if fermentation does take place, the heat may be evolved rapidly and be of only short duration. About 10 to 12 days before the manure is to be put in the pit it should be placed in a flat pile 4 to 5 feet high. If it is dry it should be dampened with water, but not made soggy. The manure should begin to heat in 3 or 4 days after which it should be turned placing the inside of the pile on the outside of the new one. In 3 or 4 more days the manure should be ready to be placed in the pit. The manure is filled into the pit in successive layers of 4 to 6 inches and tramped firmly to secure uniform heating and prevent excessive settling. It is also desirable to place the soil on top of the manure at the same time, since higher temperatures that develop when the bed is fast made up tend to kill some of the weed seeds that may be present in the sop. Since a high temperature is likely to develop the first few days after the bed is made up, the planting should be delayed until the temperature drops to about 85 degrees or slightly lower.

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