How to Use a Heat Mat for Germination


Starting vegetables and flower plants from seed is more cost effective than purchasing nursery seedlings. You also have a greater choice of plants when you choose to plant from seed. Most seeds don't require light in order to germinate as light isn't required until leaves are present. Most seeds do require warmth to germinate, which there isn't enough of if you just set the seeds in a sunny window. Seedling heat mats are available that allow you to heat the soil, where the seeds need it most, to the best temperature for germination.

Step 1

Fill seedling trays or pots with potting mixture. Water each tray until the mix is evenly moist throughout.

Step 2

Sow seeds in the potting mixture, following seed envelope recommendations for depth and spacing. Cover the trays with plastic wrap to maintain moisture during the germination process.

Step 3

Set the trays on top of the seedling heat mat. Choose a location for the mat and trays where it won't be disturbed during germination.

Step 4

Plug the heat mat in and set it to the proper temperature for the type of seeds you are starting (see Resources). Most seeds require temperatures of 70 F for germination, though it differs by plant variety.

Step 5

Remove the plastic wrap once sprouts appear and relocate the tray and heat mat to a sunny window or under a grow light. Lower the temperature on the heat mat 5 F to encourage stocky plant growth.

Tips and Warnings

  • Heat mats may dry the soil more quickly once the plastic is removed. Check soil moisture daily and water as needed. Use heat mats that are sold for seedlings only. These are water resistant, maintain their temperature well and are made to be left on for long periods of time.

Things You'll Need

  • Seed trays
  • Soil mix
  • Plastic wrap
  • Heat mat
  • Grow lights


  • Maryland Cooperative Extension: Seed Starting

Who Can Help

  • Seed temperature guide by type
Keywords: using seed heat mat, seed starting, germination mat

About this Author

Jenny Harrington has been a freelance writer since 2006. Her published articles have appeared in various print and online publications, including the "Dollar Stretcher." Previously, she owned her own business, selling handmade items online, wholesale and at crafts fairs. Harrington's specialties include small business information, crafting, decorating and gardening.