How to Use Manure to Turn a Cold Frame into a Hotbed


Horse manure will raise the temperature in a cold frame, and our automatic vent openers will keep the cold frame from over-heating.

Cold frames are heated by the sun. As soon as you add another heat source (via manure or electricity) the cold frame is called a hotbed.

In our video, Cold Frame and Hotbed Gardening, Tricia shows how to position a cold frame in your garden and how to turn it into an electrically heated hotbed. Electricity is the best source of even heat for a hotbed.

Instead of electricity, you can warm up your hotbed the old-fashioned way, with horse manure.

cold frame


Manure generates heat as it decomposes. If you place your cold frame on a foundation of manure you’ll raise the temperature of the air and soil inside the unit.

1) Build a cold frame from our kits or create one on your own.

2) Choose a south-facing site in your garden, with a windbreak.

3) Mark out a hole the size of your cold frame, and dig down about 2 feet.

4) Shovel in about 4 inches of gravel, for good drainage.

5) Fill the hole with horse manure. The ideal manure will come to you mixed with straw.

6) Press down the manure and wet it with a garden hose.

7) Top the manure with 4-6 inches of good soil (no weeds!—unless that’s what you want to grow over the winter).

8) Set the cold frame on top of the soil. And start calling it a hotbed.

Frost Kissed Spring or Fall Mix


1) Use a soil thermometer to see just how hot your hotbed is.

2) Install an automatic, heat-activated, vent opener to open and close the lid of the hotbed. Choose a vent opener that can handle the weight of your lid.

3) Check your seed packs for ideal germination temperature, and plant when the soil is at that point. Soil at 70-75°F is good for germinating most vegetables. Vegetable starts will thrive, too, at that temperature.

4) For fall and early spring planting you can’t go wrong with our Frost-Kissed Seed Collection (shown above) containing 10 Peaceful Valley seed packs of organic, cool-season, vegetables.

For more information about manure heating for hotbeds, check out the Virginia Cooperative Extension, the University of Missouri Extension, and Purdue University.

Many thanks to the Virginia Cooperative Extension for the use of their helpful diagram.