Starting Seeds with a Homemade Heat Mat


We are about six weeks out from the last frost date around here, which means it’s time start seeds for a lot of the warm season crops. Last weekend we started seeds for 11 varieties of tomatoes, 8 different kinds of chile peppers, and 2 types of tomatillos. Looking at the hundreds of varieties of heirloom tomatoes in the seed catalogs, its hard not to get carried away.


Here are the varieties I’m growing this year:

Tomatoes: Amish Paste, Black Krim, Blue Beech, Goldie, German Lunchbox, Hillbilly Potato Leaf, Mama Leone, Ox Heart, Prudens Purple, Sweet Pea Currant, and Ulster Germaid

Peppers: Ancho Gigantea, Big Jim New Mexico, Black Hungarian, Fish, Joe’s Round, NuMex Joe E. Parker, Santa Fe Grande, and  Tam Jalepeno

Tomatillos: Puebla Verde and  Purple

We started a few flowers too– hollyhocksMexican sunflower, and Bishop’s Children dahlias.

While I’ve found that most other seeds sprout just fine at room temperature, these ones, especially the peppers, won’t do much of anything if they’re not nice and cozy. Some people are able to find a warm spot in their home that works just fine. There is no warm spot in my home, which means we needed a little help. You can buy a seedling heat mat for this purpose, or you can rig one up yourself with a string of rope lights. We duct taped a string of lights to a board and laid a sheet of plexiglas over it. Our seedling trays are sitting on top, where the heat from the lights keeps the soil at about 80 degrees. Just make sure your using old incandescent lights and not LEDs, which won’t give off any heat.


11 thoughts on “Starting Seeds with a Homemade Heat Mat

  1. Very cool. Ok the farmer and I were having the argument this morning is it the light or the heat or both that gets the seeds like peppers to germinate? I think you need both to get a faster germination rate. What do you think?

    • Hmmm. . . I know some seeds need light to germinate (particularly very small seeds) but I haven’t heard this about pepper seeds. They definitely do need heat though. Putting the trays in a sunny spot will help keep them warm at least, so I guess the light can’t hurt!

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  3. I’m passing this along to my husband. We have the same trouble with finding a hot enough spot in our home during the winter for the pepper and some herb seeds. We’ve looked at the heat mats but were reluctant to spend the money. This is a good solution!

    • Thanks. I agree, I hate to spend a lot of money on this kind of thing. I’d much rather blow my gardening budget on seeds and plants!

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  5. Too bad my husband cut up our only remaining string of incandescent Christmas lights to use as a demonstration in a science class. I’ll have to go with finding a sunny spot. :)

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