Improve Seed Germination
If you’re looking for a way to kick your seed germination into high gear then check out the video below. By using a simple method of insulating the seed starting tray you can improve you shorten your germination times, increase your germination rates, and save energy.
How To: Improve Seed Germination Time and Rate
Most seeds require, or at least will benefit, from warmth when germinating. Simulating the end of winter and the warming soil and sunshine of spring is what triggers seeds to germinate. If you attempt to germinate in a cool area such as an unconditioned basement the germination rate will likely be slow. Some seeds may not germinate at all without supplementing some heat.

By using a seed tray warming mat you can definitely improve your seed germination rate. Sadly, most of the seed tray warming mats are very inefficient. They’re usually only designed to keep the tray 10-15 degrees Fahrenheit above the ambient (air) temperature. NOTE: Seed warming mats should always be used with a temperature controller! If your seed starting area is 60 degrees the best you can hope for is 70-75F in your tray. Not to mention the seed warming mat will likely run close to nonstop to achieve these temperatures. Additionally, those temperatures are at the bottom of the seed tray, not even at the soil level of the seeds. Some seeds like tomatoes and peppers, especially super-hot peppers, have a recommended germination temperature of over 80F.
Using insulation around your seed warming tray will retain all the heat produced by the warming mat. Additionally, the seed tray will have a consistent temp from top to bottom, even the air in your humidity dome. Using insulation around my seed starting tray I was able to easily achieve 85 degrees F. Some super-hot pepper seeds I have that say might take up to 30 days to germinate. Mine sprouted in just 7 days using this method.
What Materials Can Be Used to Insulate the Seed Tray?
You could use Styrofoam or similar materials to insulate. My preference is the foil backed bubble wrap insulation seen in the video above. The bubble wrap is easy to work with, it’s thin, can be cut with scissors, held together with tape. It also has many other uses. For the best adhesion use foil tape, made with aluminum, for the bubble wrap.
The foil backed bubble wrap can serve many other purposes as well. I even used it to line the shelf of my grow out area. This is helping to maintain a better temperature for my plants. As a bonus it helps reflect light back to my seedlings that would otherwise be lost.
If you’re using a seed starting mat then why not get the most of it. Not only will you make your germinating seeds happier but you’ll save some electricity in the process. Do you have any experience with using insulation around your seed starting tray? If so, I’d love to hear about your experiences in the comment section.
If you live in Michigan, we started a Facebook group for selling and swapping plants and seeds. Click here for more information about our Plants and Seeds Buy/Sell/Trade Facebook group.