DIY Garden Hotbeds

Cold frame is a transparent-roofed enclosure that is built into the ground and is used to protect plants from cold weather. The function of building hotbeds in your garden is to provide heat for the plants in cold temperatures. These hotbeds will allow you to plant seedlings outside your house when the weather is still cold for the overwinter tender plants to bear. Hotbeds are great for any winter vegetables such as lettuce even after the temperatures outside have dropped too low for the plants to produce. Cold frames, which are glass-topped boxes, are built to keep the hotbeds inside. The cold frames allow the sun to get through, but prevent the cold winter air from getting inside. Here are the steps on how to build your own garden hotbeds.

You will need:

  1. Cold Frame
  2. Burlap
  3. Thermostat
  4. Sand
  5. Heating Cables
  6. Burlap

Garden Hotbeds


  1. Firstly, measure the width and the length of the cold frame’s base. Make 12 to 14 inches of deep pit that suits the cold frame dimensions.
  2. Then, set the cold frame into the pit before placing the frame, so the slope of the glass lid faces the direction that receives the most sunlight. Place about 6-inch of gravel into the cold frame. Spread a sheet of burlap over the top of the gravel before covering it with a layer of clean sand about 2-inch thick.
  3. Place the heating cable on top of the sand about 3 inches from the side of the cold frame. Run it the length of the cold frame, loop it and then run it down a second row, which is placed 6 inches away from the first cable row. Keep running and looping the cable until you reach the end of the cold frame.
  4. Next, plug the cable into the thermostat and plug the power source of the cable and the thermostat into an outdoor wall outlet. Cover the heating cable with 2 inches of sand before covering the sand with a second sheet of burlap. Place again a second of 2-inch sand on top of the burlap. On top of the sand, you can start to set the plant.
  5. A hotbed can be overheated if the cables even if the cables are turned off on sunny days, so open the top of the cold frame to help the temperature inside regulate. The temperature of the hotbed can be adjusted with the thermostat as seeds germinate at temperatures between 70 to 75 F while plants grow at temperatures between 65 to 75 F.

Image Credit:

Flickr CC

Additional Reading:

The American Gardener: A Treatise on the Situation, Soil, # and Laying Out of Gardens, on the Making and Managing of Hot-Beds and Green-Houses and on the … of Vegetables, Herbs, Fruits, and Flowers.

The English Gardener: Or, a Treatise On the Situation, Soil, Enclosing, and Laying-Out, of Kitchen Gardens; On the Making and Managing of Hot-Beds and … Sorts of Kitchen-Garden Plants, and of Fruit