Heat for Hot Peppers

Last year I skipped using a heat mat underneath the flat in which I started my hot pepper seedlings.  That was a big mistake.  I had a germination rate of less than 10%.  This year I picked up a new heat mat and have had great results.

It’s already time to start hot peppers in Austin.  They can be transplanted into the garden as early as mid-March and it takes 8-10 weeks from the time seeds are sown until the seedlings are ready to transplant out.

Hot peppers germinate best around 80 to 85 degrees Fahrenheit.  Since I don’t keep my house that hot they need supplemental heat.  There are fancy heat mats that come with thermostats and soil thermometers, but I picked up a less expensive one that simply raises the temperature of the flat 10 to 20 degrees above ambient temperature.  For my purposes it has worked fine.

In the picture you can see that I’m also using a plastic cover over the flat to both retain moisture and heat.  The heat mat does make the soil in the flat dry out more quickly; I have had to mist the flat daily.  One thing to watch for with the plastic cover is that it may reduce air flow and get moisture levels too high, creating conditions for fungal growth on the plants.

The covered pepper flat.

My flat has 72 cells.  I planted 6 varieties of peppers on January 2.  I first began to see germination on January 6, but some of the seeds are just sprouting now, on January 13, and I expect a few more to still germinate.  The seeds that I had from the 2010 growing season are taking longer to germinate than the seeds packed for 2012, but the slower germination may also have to do with the variety.

I sowed two seeds per cell to ensure getting close to 72 plants.  In the cells that have two seedlings I’ll use a small scissors to cut out the weaker plant.  I don’t want to pull it out as that may disturb the roots of the remaining plant.

Pepper Seedlings

Once the peppers grow their first set of true leaves I’ll transplant them into 3 ½ inch pots.  I like to grow a lot of peppers, but I won’t need 72 plants; so I’ll have a few to give to friends.

Tags: , , , ,

6 Responses to “Heat for Hot Peppers”

  1. Rick says:

    This is my favorite part of gardening- watching the little ones grow.

  2. Geoff says:


    Thanks for the comment. I enjoy this part, too. I miss having a greenhouse, but grow lights are working for me right now.

  3. Cathy says:

    What type of light did you use…I am still shy over starting seeds…I am in a short growing season..so would be nice to get started earlier..I usuallly just but transplants…cost wise I cannot justify buying all the equipment but maybe I am wrong…thanks for your time

  4. Lora says:

    I use an old electric blanket for a heat mat. It works great and only needs a bit of plastic on the top. I live in Washington State on the East Side of the Cascades and I’ve been thinking about starting my peppers too. But wonder if it’s too soon.

  5. Geoff says:


    According to the planting calendar put out by the Washington State Master Gardeners, http://www.spokane-county.wsu.edu/spokane/eastside/june.htm peppers are transplanted out to the garden in June in the eastern Cascades. If this is the case for you, you’ll want to start your peppers indoors 8 to 10 weeks prior. So for a June 1 outdoor planting, start your peppers indoors mid to late March.

    Thanks for visiting our site,


  6. Geoff says:


    I use one of the LED grow lights that we sell on our website. I don’t have a sun room or any windows that get a lot of light in my house. If you do have windows with good light, you might be able to skip the grow lights, but I find that they make a big difference.

    I have also used the less expensive T-5 grow lights with good results. However, depending upon the size of your seedling flat you may want to get a set-up with at least two bulbs as I have found that one bulb does not provide good enough coverage for a large flat of seeds.

    Thanks for visiting our site,