When you are learning to grow from seeds, often you might see reference to a heat mat for seedlings. Heat mats can really help speed up germination for many seeds, especially tomatoes and peppers. You can buy them, but here I will show you how to MAKE one.
Here’s what I used:
- 2 old humidity domes for seed flats (the flats had been broken)
- 1 string of indoor/outdoor Christmas lights (the orange lights were not working)
- All-purpose sand
That’s it! It’s actually quite simple. I thought of it when I was watching my dad install the tubing for his radiant floor heating. You can use pretty much anything for the tray. Even old drawers! I actually have an idea bouncing around in my head for a grow rack made from an old dresser… anyway, back to making a heat mat for seedlings!
The basic concept is this – set out your trays, whatever you want to use to hold it. They need to be at least the same size or bigger than the seed flats or boxes you will be placing on to them. Arrange the lights in such a way that they are on the bottom of the tray and evenly spread out. Kinda like this!
Then I poured sand over the top to almost completely cover the lights. It went a lot better if I physically held the lights down while I poured the sand, less lights poking out the top. It ended up looking like THIS:
After that, I just set the seeded flats right on top of it. You can use pretty much anything for this, anything that has sides that are at least a couple inches high.
OK, the photo above has unseeded flats on it just for demonstration. So here’s a photo of the flats that I actually DID seed and use with this. This is a day after sticking them on there. Note the condensation on the humidity domes – the sand does a phenomenal job of holding and distributing the heat from the Christmas lights. Consider, also, that this is in an unheated garage, it’s probably in the 30s in there normally, maybe in the 40s. Inside the grow rack, it is just the right temperature for my seedlings. You can feel the warmth when you stick your fingers in the sand – not hot, but a nice gentle warmth.
The best part? The whole thing cost me a big fat whopping NOTHING! Much better than that! Having said that, if you do decide to opt with buying a heat mat for seedlings (and let’s face it, $30 isn’t really THAT much), feel free to check them out at Amazon.com, which is where you generally will find the best prices. Anything purchased through the below link will help go to support this site (at no extra cost to you!) so we certainly wouldn’t mind if you bought one from them