A Seed Starting Heating Mat Makes an Excellent Worm Farm Heater

I keep composting worms indoors (under my desk at work) and outdoors (on my fully shaded back porch). During the winter, the worms need a little help to stay warm. A worm farm heater can help! Remember, composting worms do their best work (eating, pooping, making babies) between about 60 degrees F and 80 degrees F.
Keeping your worm bin warm in the winter will not only keep them more efficient at their 3 primary jobs, it might be essential to keep your composting worms alive. Remember, worms can freeze if the temp inside the bedding drops too low.
There are lots of ways to keep your worm farm warm in the winter (here are a few: 6 ways to keep you worm farm warm). One of the best and easiest ways is to use a seed starting heating mat as a worm farm heater.

Seed Starting Mat I use as a Worm Farm Heater

A seeds starting heating mat is a flat, waterproof mat used underneath seedlings to warm them up and give them a head start on the growing season. The mat that I use for my worm farm heater is the VIVOSUN Durable Waterproof Seedling Heat Mat Warm Hydroponic Heater Pad. It is available on Amazon for only $12.99.

I use the 10 inch by 20.75 inch model because it fits the best in my worm bin. I am using the Hungry Bin for the test below but the mat also work if you fold the edge to fit in a Worm Factory 360. VIVOSUN also makea a 20 inch by 20 inch and even a 48 inch by 20 inch version for large worm composting bins.
The VIVOSUN claims to raise the temperature 10 degrees F to 20 degrees F above the ambient temperature.

Instructions for Setting up and Using your Worm Farm Heater

• Your worm bin heater will arrive rolled up inside its packaging. Remove the mat and attached cord from the box.
• Plug in the cord to a standard 120 volt outlet and unroll the mat. As it warms up the mat will soften and lay flat.
• Simply lay the worm farm heater mat on top of your worm bin directly on the worm bin bedding. Remember, worms move upward as they process food. Most of your worms will be in the top 4 to 6 inches of worm bin bedding anyway so this is the most important section to heat.
• Add the lid or cover back to your worm bin on top of the worm farm heater.
• Remember to remove the worm farm heater once the winter has passed.

My Test of the Worm Farm Heater

So, does it work? Let’s find out! I used the GDEALER Instant Read Thermometer ($12.99 on Amazon) to test out the impact of the worm farm heater.

Results:

• Ambient Temperature (air temperature outside the worm farm): 51.1 degrees Fahrenheit
• Temperature of the worm bin bedding without the worm farm heater: 65.5 degrees Fahrenheit. It’s important to note that even without the heater the worm bin bedding was 14 degrees F warmer than the air temp outside the bin. So, even when the air temp is freezing it may be warmer inside your worm bin. Always a good idea to have a thermometer to know exactly what is going on temperature wise in your worm bin.
• Then, we added the worm farm heater to the top, plugged it in, and waited an hour for it to do its thing!
• Temperature after an hour with the heating mat: 74.1 degrees Fahrenheit.
• Results: the worm farm heater raised the internal bin temperature by almost 9 degrees.
• NOTE: I completed this experiment for the sake of the experiment. With a bedding temperature of 65.5 degrees, I didn’t really need to add the worm farm heater. In practice, I only use the heater when the bedding temperature drops to around 50 degrees or so.

Worm Farm Heater Conclusion

A seed starting heating mat makes a great worm farm heater. It did its job, was super simple to use, and for $12.99 it is well worth it to keep your composting worms nice and cozy this winter.