Winter Worm Bin Heating – A Novel (and Festive?) Approach

Tis the season to pull out all those dusty boxes of Christmas lights and decorations and start ‘decking the halls’ with the stuff.

While I DO enjoy the end product (the decorated house), the prospect of actually doing the decorating is something I dread each year. Invariably, it seems (according to someone who shall remain nameless) that our current decorations are not quite up to snuff for this year, and as such, that multiple trips to the store to buy more are warranted. Of course, this approach seems to leave us with {cough} perfectly good {/cough} stuff that is no longer needed.

Among the casualties this year there were a couple of lengths of rope light, no longer welcome out on our back deck, where they had added a dull blue shimmer for the last couple of holiday seasons (OK, I’ll admit – these weren’t the nicest of Christmas lights). When told to “get rid of them”, I (being the pack rat that I am) of course snuck off with them and put them out of harms way.


Well, aside from the fact that I’m a “waste to resource” kinda guy in general, these lights MAY be able to serve a different purpose this year – helping to keep some worm bins warm down in my basement.

This particular application (bottom heat for worm bins) is my idea, but credit for the concept in general definitely goes to David LaFerney, and his fascinating article “Home Made Bottom Heat for Seed Starting (or pet bed)” on his website, “The Door Garden” (a very interesting site in general, by the way).

I stumbled on the article back in the summer, and immediately saw the potential for keeping worm bins warm during colder weather (in an unheated garage, cold basement etc). Of course, it didn’t make all that much sense to write about it then, so I made a mental note to revisit the idea again in the fall.

As is often the case with my “mental notes”, this one ended up crumpled up and hidden in the dark recesses of my noggin, and if it hadn’t been for the recent incident with our unloved rope lights, it might have been fallen into the “void”, never to be thought of again!

The basic concept here is to create a simple framework of channels on top of a bench/table for the string of lights to sit in, and then to put some sort of a surface over top (upon which your worm bins, seedling trays, pet beds etc will sit). David used hard styrofoam for the channel walls and a piece of drywall for the surface – he actually took it one step further than that by adding a sheet of vinyl flooring as well (to make the surface waterproof).

Because the lights only get slightly warm to the touch there is virtually no fire hazard (I’m no fire marshall – this is just based on the opinion I share with David), and since the lights are designed for outdoor use there wouldn’t be a shock hazard either.

As far as I’m concerned, David’s creation is nothing short of brilliant. As he points out himself, commercial bottom-heating pads can cost quite a lot of money, and will only heat a relatively small area. With this approach you can create a much larger surface, and for a lot less money. Since these are very low wattage lights, the cost of running this set up won’t likely be very much (or use up much power) either.

The only downside might be the fact that it’s not controlled via a thermostat of any sort (although I wouldn’t be surprised if the really enterprising DIYers out there could come up with something).

Anyway, I HIGHLY recommend you check out the article on David’s site (linked to above)! He outlines everything in great detail and provides a lot of really helpful photos.

Oh, and don’t forget to come back and share your thoughts here about the potential worm-bin-heating application!

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  1. This is pure genius for those of us with worms in a box in an unheated garage. And these light ropes will be discounted soon after the Christmas holiday. I only hope that I can find a red one so the worms won’t freak out. If not red, then I will wrap with duct tape.
    Thanks for the tip!

    • Bentley
    • December 4, 2009

    Hi Steamyb,
    If you create a bottom-heating system the way David (creator) did, you certainly won’t have to worry about bothering the worms with any lights, since the rope lights will be down beneath the surface that your bins sits on. My image above definitely doesn’t depict a suggested set-up, ALTHOUGH – I supposed rope lights could also be used as a lower power method for keeping worms down in their bedding as well!

  2. Great idea! I use Christmas lights on my dwarf citrus trees to keep them warm outside during the Winter.

    • Kate
    • December 5, 2009

    We currently have many ‘Bentley Boxes’ on the side of the house with lights under them. The boxes are sitting on bricks and the lights run underneath. The worms are very happy and active despite the first few frosts here in Sacramento. The only challenge has been that they dry out from the bottom up so keeping an eye on the moisture is important.

    • Bentley
    • December 11, 2009

    JILLIAN – that is cool. I’ve never really though of that as a good way to keep a tree warm – but it makes sense!
    KATE – sounds like this “Bentley Box” notion is getting spread around! LoL!
    Anyway – great idea with the lights!

    • jim144
    • December 15, 2009

    I have 2 55gal gallon drum built into flow thru bins. They are big and bulky, and would normally (I believe) be hard to keep warm. While thinking about how I was going to keep these bins warm in my garage I had an epiphany. Last summer (2008) I did some work on the soffets under the eaves of my roof. I live in Michigan, and have always had a problem with Ice buildup along the edge of my roof. So, several years ago I broke down and bought some of those cables that are used for melting the along the eaves of my roof. They worked, to a certain extent, but I am never satisfied (so my wife and kids tell me). So when I ‘opened up’ the airflow in the eaves, I eliminated 90% of the ice buildup (the blown in insulation helped alot there too!). Long story short …. I wrapped one of these ‘eave heaters’ around the bins (one of these cables was long enough for both). Problem was, they would get really warm. Too warm for prolonged exposure. So I bought an electrical timer, bought extra pins for it, and set it up to turn every 6 hours for 2 hours. This has worked pretty well. The cables are wrapped multiple times around each bin, with an inch between each coil (i still had the wire hangers from when I purchased them). With the temp hovering in the teens ot low 20’s outside, the temp inside the bins have pretty much stablized at between 55 to 60°F. I check the temp daily, as you can never foresee any problems and problems always show up when you don’t want them too …..


    • Bentley
    • December 16, 2009

    Thanks very much for sharing, Jim! Great info!

    • Tim
    • December 19, 2009

    You can solve the regulation problem with a simple dimmer switch like you us in the house for lighting. Pick one up at Lowe’s, or wherever, and simply place it between your power source, and the light rope, or whatever you are using. If you have ever tried one of these for a light switch, then you know they control how much power goes to the light source, it would do the same for the rope.

    • Shaul
    • January 5, 2010

    Thanks Bentley for a great idea. A couple weeks back, after seeing your article, I bought a 5-meter length of rope light. My bin is outside on my patio and (here in Jerusalem, Israel) we do get snow in the winter, so i’ve been looking for a reliable heat source. The rope light says 16W/meter; so 5-meters at 16W= 80W. I tried putting it inside the bin (on top) underneath the cover, but it got too hot (like trying to hold a lit 80W light bulb in your hand), so I came up with the same idea as Tim. I bought a dimmer switch and installed it with a plug and socket. The dimmer plugs into the wall and the rope plugs into the dimmer. This way I can also use the dimmer separately for other things. It works perfectly, giving me the full temperature range from low to high. I want to add that the rope is made up of tiny bulbs (not LED’s) because LED’s won’t work with a dimmer switch. Also I read somewhere that the worms aren’t affected by red light, so if you have a light with a red filter, the worms won’t try to escape. On the basis of that, I bought the rope light in red. Though the lights are white, through the red-colored rope, they appear red as well. It will be interesting to see whether the worms try to escape or not.
    Thanks Again,

  3. So I went to Wally World after Christmas and bought an 18’ red rope light at 50% off ($3.49). I wanted it to be red so that when I buried it in the worm box, the worms would not freak. My worm box is 4’x3’x2’, so I was able to dig a ditch in the VC (6-8” deep), line the ditch with shredded cardboard, and bury the red rope light under the VC. I then leveled everything out and covered it with plastic sheets. This rope light was long enough to make 2 laps around the inside of the box with a 3-6” space between everything.
    Results: Outstanding increased microbe activity and the worms love it. The covering plastic was just barely moist before the rope light addition, now when I raise the plastic sheets, water runs off in streams. This has always been my way of telling that the microbes in the box were doing their thing, and in the winter in my unheated garage, the microbes basically went dormant. And with nothing to eat and cold temps, the worms hibernated to a certain extent.
    With the rope light installed, the worms think that spring is here. No winter slumber party for these guys and gals (whichever?). These kids are hooking up like its prom night. I leave a light on to keep them down, but that hasn’t slowed them down at all. It is almost embarrassing.
    Todays inside garage temp:40F
    Todays inside the box temp: 60-65F

    • Bentley
    • January 8, 2010

    Interesting stuff everyone – thanks for sharing!

    Looks like I will be putting my rope lights to use fairly soon. I’ve let things get really cold in my winter windrow so I’m going to add a bunch of new material and see if I can kickstart a warming trend with the lights.
    Should be interesting!

    • Eric Wichert
    • October 13, 2010

    Has anyone tried using a water bed heating pad? The thermostat goes down as low as 70 deg on the one I have. The only problem I see is since it is a pad it would reduce air flow a little. I have a small 3′ X 2′ flow through design I am experimenting with. Since my wife thinks I am crazy for even having the worms I am trying to keep costs down to a minimum. 🙂


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