It’s seed-starting season and, like every year, the questions begin rolling in. We’ve received a lot of questions about DIY seedling heating mats recently. We absolutely understand the frustration.

The seedling heating mats available at Amazon.com, always our first shopping choice, are garbage, made in China. From mats starting fires to mats that don’t ever heat, it’s a disaster. So, we looked for alternatives.

The DIY solutions we found online typically called for “Christmas lights” or rope lights, buried in kitty litter (the non-clumping type) in a Sterlite container.

It sounded interesting enough but, as skeptics, we needed to find out for ourselves if it truly works.

Since the rope lights (incandescent) struck us as being far safer than a string of holiday lights, we took that path.

We totally bought into the whole concept, buying the Sterlite container from Walmart, the rope lights from Lowe’s and the non-clumping kitty litter from our local grocer’s.

The reality

The rope light instructions clearly state that they should never be “covered.” This was not mentioned in the product description on Lowe’s website.

So, that nifty DIY plan that recommends you bury the rope lights in kitty litter? Won’t work.

Just for ducks, we proceeded without the kitty litter. We placed the rope lights in the Sterlite container, suspending the germination pots above the lights on a rack ( a cookie cooling rack from the kitchen).

Our method

We used one plastic pot and one terra cotta pot, filled with seed starting mix.

Since most of the DIYers who have written about this project online used meat thermometers to check the soil temperature, we did too.

We checked the soil temperature starting at 15 minutes after placing the pots on the rack to one hour and saw no rise in soil temperature.

Ok, we thought, the rack is holding the pots too high, so we got rid of it.

We placed the pots directly on the light string and checked temperatures every 15 mins until we hit the highest.

We were aiming for 80 degrees F soil temperature and the highest reading we got was 72.6 degrees for the soil in the plastic pot and 68.5 degrees for the soil in the terra cotta pot.

And, this was after sitting directly on the rope light for more than two hours.

Needless to say, this is a lame idea.

We recommend that you purchase a real seedling heat mat. We bought ours at Bootstrap Farmer but you can also order a Ferry-Morse heat mat online at Lowes.com.