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

cold frame manure diagram

Warm up your cold frame with help from your friendly barnyard animals

Horse or chicken 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 or chicken manure.

Manure can make your cold frame a hot bed

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. 

Get the hotbed ready to plant

  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.


Take the chill off your cold frame, warm it up with manure, and enjoy the gardening flexibility of a hotbed all winter long.

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For a heated cold frame does the manure have to be replenished every year ? Thanks

Graham Miles

Do you have change the manure every year to maintain heat in a cold frame ?- Many Thanks

Graham Miles

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