Soil Warming Cables

by Bob S

I saw these soil warming cables.

I used a string to string around my bin to determine the approximate length of cable needed. I measured 12 feet. The closest I could get to that was 14 feet.



When I got it, the instructions suggested using a piece of .5” x .5” hardware cloth to tie the cable to using string, twine or the plastic hardware ties. For my bin I cut a 24” x 14” piece of hardware cloth and used twine to tie it in place. The length was almost perfect (better to be lucky sometimes than good).



It suggested placing the thermostat in the center. My thermostat came within about 3” of being in the center. Close enough for me.



I have a test bin with no worms. I took about 2/3 of the bedding out and placed the hardware cloth with the cable facing down (per cable instructions), then covered cable and hardware cloth with the bedding that had been taken out.



I plugged the cable in and began my test. I have holes around the side of the bin near the top of the bin. There are also holes in the lid of the bin. I covered the top of the bin with a large towel. I left the holes on the sides and ends open. The bin is a 31 gallon from Lowes Home Center. The bin does not have any other insulation. With the exception of the towel on top, this is about the worst case environment as far as the bedding being exposed to the elements.



So far the weather hasn’t be very cold. Tonight the temperature is to get down to about 15. That is if you can believe the weather reports.



So far the lowest temperature has been 28 and the high 36. The temperature of the bedding at about the 2-3 in depth has been from 66-70 degrees. The thermostat for the cable is set to come on at 74. Not sure what temp it goes off.




Once I do this worst case testing, I’ll wrap the bin with a product called n-sulate. A friend who has been a master gardener for many years gave me two 6’ x about 40’ pieces to use to test. I plan to wrap the bin with this material and test to see how well it insulates. This n-sulate seems to be a pretty good product, so I expect it to help a lot. Being 6 foot wide, I plan to wrap it under the bottom and over the top to help insulate. I’ll make a few holes for air flow. I’ll probably start with 2 holes, then 4 holes, then maybe 6 holes. This, to me, if it works seems to be the easiest way to warm a bin.



There are some minor problems that I may encounter. Turning the bedding periodically will be a bit more of a problem. I’m not sure of the reliability of the cable: how long it will last or how accurate it will continue to be.



One thing I will not be considering in my testing is any heat that could be generated from feeding worms.



Again temperatures are: 28-36 outside, 66-70 at a depth of 2-3” in the bedding.



This bedding temperature is probably the best case. These temperature to date are taken in the middle of the bin, not out around the edges. That may be done later.



The cable I purchased was from eBay:

http://www.ebay.com/itm/380173048386?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649



Updates will be given periodically. Lessons learned as well as successes will be included.



Good luck, I hope this helps,