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How to Build a Seed Incubator

Over the years I have always started my seeds in a homemade "incubator" located in the greenhouse. It was a way to get optimum lighting and still not have to spend the money to start up those big giant heaters in the greenhouse quite yet. Using the incubator kept my little babies warm at night without having the fear of losing them to frost.

With a few supplies like heat mats, timber and foam insulation, you can make an incubator in no time flat!

Depending on how much room you have available, you can design your incubator as big or as small as you'd like.

Here's what you'll need:


-Foam Insulation

-Heat mats (Agritape)

-Heat mat temperature controller

(Heat mats and controller can be found at various greenhouse supply companies. Here's one from Harris Seeds. )

-Small piece of gutter

-Capillary mats (for wicking purposes)

I found my capillary mat from Farmtek

-A little bit of silicone to seal ends of gutter


I built the frame of my incubator to fit on the top of one of my greenhouse benches. It allows for easy access and once I am done germinating I can easily lift it off and use my bench space again.

Once the frame box is built (to whatever dimensions work for you and your space), I lined the bottom of the box with foam board insulation. This will help keep the heat in at night.

After the frame is built and the insulation is added, we can now start adding our components. I layed 3 Agritape Heat Mats that went to width of the box. There are various size options, so have your dimensions figured out before buying the mats.

In order for the heat mats to work properly they must be plugged into a temperature controller. This will allow you to set the mats to a particular tempature. Different seeds require different growing temperatures. The common temperature is right around 70 degrees.

Next step; Adding capillary mats.

I recently discovered capillary mats by reading Bare Mountain Farm's Blog. This system has been a big game changer. I no longer have to worry about being home all the time to water. The wicking method works great and is so much better for the seedlings. The mat basically works by wicking the water supply up through the bottom of the seed trays. Keeping the water where the roots are!

Bare Mountain Farm has a great blog on it and shows another method to building a seed bench.

So in order for the capillary mat to work, it needs a source of water. I took the advice from Bare Mountain Farm and used a small piece of gutter and sealed the ends.

Using siccors, I then cut the mat to fit in the gutter and up into the frame, covering the whole bottom of the box. The mats can be layed right over the heat mats.

Spray down the entire fabric to jump start the wicking and fill the gutter up completely. I usually have to add more water to the gutter every other day. (It's alot better than misting every few hours like I had been doing!)

Lay a sheet of polycarbonate over top to keep heat in and still allow for natural lighting. On sunny days, I remove the top and vent the greenhouse. Our objective isn't to fry the seedlings but instead keep the soil at a constant warm temperature to jump start them into production!

If you have any questions and want to reach out, email Jayflora @

"For a seed to achieve it's greatest expression, it must come completely undone. The shell cracks, the insides come out and everything changes. To someone who doesn't understand growth, it will look like complete destruction." -Cynthia Occelli


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