Root Zone Heat Mat

Heat Mats are an easy, energy efficient way to promote faster germination and stronger seedling growth. They emit gentle, uniform heat to warm soil evenly and encourage root formation. Most seeds require soil temperatures in the 75 to 90 degree F range for successful germination. In your home or greenhouse, the air temperature may be 70 degrees F or warmer, but the moist soil in your seed flats will probably be much cooler than that. Root Zone Heat Mats are a reliable, efficient way to boost soil temperature.

The Heat Mat contains heating elements bonded between sheets of durable Mylar. It can be used anywhere indoors - on a windowsill, table, under grow lights, or in the greenhouse. The mat can raise soil temperatures 15 to 20 degrees F, yet it uses less electricity than a 40 watt bulb.

Using the Heat Mat

The Heat Mat can be placed under flats of cuttings, seeds, or under individual pots. 

  1. Unroll the mat before plugging it in. Center flats or pots on the mat.
  2. To vary the amount of heat, place a saucer, coaster, pot holder, or thin piece of wood between the mat and the base of the container. As the distance between the heat source and the base of the plant increases, soil temperature decreases. It may take up to 24 hours for the soil temperature to increase and level off (especially with large pots of soil).
  3. When germinating seeds, you can help keep soil moist by covering the seed flats or containers with clear plastic wrap or use covers which accompany many growing trays. Do not allow the growing medium to dry out. Be sure to remove the plastic as soon as seedlings emerge.
  4. Check the soil temperature occasionally to be sure it remains near the optimum temperature recommended in the chart at the end of this bulletin.) You can monitor temperatures with a propagation or soil thermometer, available from our catalog or many garden centers.
  5. After seeds have germinated, remove the heat mat and move growing containers to a sunny windowsill or under grow lights. Once they have germinated, seedlings no longer require high soil temperatures. If you are growing in a cool room (50 degrees F or less) you may wish to leave your seedlings on the heat mat with added distance between the flats and the mat (see step 2). Cuttings can be left on the mat until roots are well established.

When using the Heat Mat, please remember:

  • Be careful not to puncture or cut the mat.
  • Use only indoors. It is not rated for use outside.
  • Inspect wires and connections for damage or wear.
  • Do not operate the mat with any plug other than that supplied with the transformer.

Last updated: 06/15/2023