Answer: The hottest of all manures is poultry manure, but any manure will work just fine as long as it is fresh. Hot beds get their heat from fresh manure decomposing. You can also build a hot bed by installing a heating cable under chicken wire in the bottom of the frame.
Be sure you pay attention to venting the hot bed during the day. A lot of heat can build up quickly and you don't want to cook the plants. Otherwise, just use the same principles as you would for a cold frame. Watch your moisture levels, cover the frame on the coldest nights with a blanket, bags of leaves or straw to keep in the heat. Keep a thermometer inside to keep an eye on things. And be sure to harden your plants before putting them out in the garden.
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