It’s getting hot here in Texas. Coming from Northern AZ, this will be the first summer I will have to contend with heat that could potentially kill my worms.
Red wiggler worms need temperatures roughly between 40 and 90 degrees Fahrenheit to survive.
Keeping Worm Bins Cool
In the summer, keeping worm bins cool can be a challenge. Here are some guidelines:
- Keep bins indoors – The easiest way to beat the heat is to keep worm bins indoors. Even if you don’t have air conditioning, your house is probably a little cooler than it is outside.
- 100% shade – No exceptions on this one! Direct sunlight can heat up a worm bin fast and kill worms fast. Make sure you know your outdoor spot gets no direct sun and make sure that doesn’t change as the movement of the sun changes.
The sun will climb higher in the sky and rise further to the north, the closer we get to summer solstice on June 21.
- What about the garage? – It depends on your garage. Garages are shady, it’s true. However, some garages are stifling, hot, and very unpleasant. If you wouldn’t want to spend an hour in there, assume that your worms won’t like it either.
- Earth as insulation – partially burying your worm bin into the ground can help protect worms from high summer temperatures. Make sure it’s in the shade!
- Open lids – Open the lids on your worm bins to help heat escape. For plastic tub worm bins, this is a necessity. During the summer, excess moisture will keep a plastic tub bin soaking wet. If you’re worried about critters and such, put the lid back on at night and open in the morning.
- Water, water, water – Keep bins plenty moist. For one, you don’t want them to dry out and kill the worms. Second, water removes moisture as it evaporates. Put a thick layer of shredded newspaper on top and keep it watered down. As it dries out, it will help remove heat from the bin. Those of you who use swamp coolers know exactly what I’m talking about.
As mentioned earlier, plastic tub bins are prone to water logging, so use a spray bottle and mist frequently instead of adding water directly.
- Careful with food – Adding food to a worm bin can cause it to heat up. In the winter, we welcome foods that cause our bins to heat up a little. In the summer, this could be disastrous. You may want to pre-compost your worm food before adding it to the bin. That way it heats up before it gets to the bin. I talk about pre-composting worm food in this article about feeding.
I hope these tips help you out over the summer. It’s important to remember that what was happening in your bins over the last few months is not necessarily what will continue to happen over the summer.
Food is going to break down faster, hotter, and release more water. Worms will be more active and so will the microorganisms in the bin.
Worm Bin Insulation
Any way you can dream up to insulate your bin can help keep it cool. Things like foam insulation sheets, adobe brick, and shade cloth can all help if properly used. You’ll have to evaluate your situation and come up with a plan.
In extreme emergencies, water frozen in plastic jugs can be added to worm bins to help cool them. However, I personally don’t want to have to deal with freezing plastic jugs on a daily basis.
How are your worms doing this summer? Post in the comments and let us know.
{ 8 comments… read them below or add one }
Hi,
I’m interested in cooling a “vermicomposting trench”. The trench has about 6″ of hay on top. When I’m watering my plants I’d like to include the trench, but I’m concerned about the chlorine in the water. Right now I rely on natural rainfall to keep everything moist. I’m considering spraying the hay lightly. Then I’ll get some evaporative cooling without harming the worms. Any suggestions?
Tom, well it depends how hot and dry it is where you are. If you were here in San Antonio, I’d say water that trench every day! It’s worth the risk of chlorine.
I’ve been watering my outdoor flow through daily with tap water and haven’t had any problems.
If it’s not in the 90′s and/or very low humidity, you might be able to get away with spraying the hay on top.
You could also cover the top with burlap and keep that wet. It might have enough oomph to keep the underside moist but still let it breathe.
I think your best bet is to just water it with the hose.
Does anyone call you Wormmama Cass? I’m in Austin where I have two black bins (I’m going to paint future bins white) and I have pushed the limits on temperature extremes in both directions. In the Winter, a cheapest you can get, aquarium heater in a bin of water works just fine for Central Texas and it only needed to be plugged in for about five days. Last Summer I switched out bottles of ice everytime it went over 90 degrees. This year I did the same thing until I said forget it and left the bottles in place. It has been over 100 degrees for almost 60 days now and I still have worms. Shade makes the difference. I check it with my compost thermometor, every once in the while, and the water temp inside the bottles never seems to get above 90 degrees. The worms hang around the bottles quite a bit right now.
Hey Wormfarmergeorge. No, I’ve never been called Wormmama Cass. Anyway, yes, shade is absolutely essential for keeping worms outside in the heat.
I put a compost thermometer in the flow through on the Northside of the house. It’s reading 80 and the air temp in 96 (not so hot today). I figure it will be easier to insulate the bin than try to keep it cool.
Thanks for the tip on the aquarium heater. Do you put the bucket of water inside the bin? I guess so.
Hi Cassandra,
I also use aquarium heaters, but I put them in coldrink bottles. They work a treat and very safe. picture on the blog
Larry
Thanks Larry. We all want safety for the worms!
connect plastic tubing to the outside airconditioner drip drain. run the tubing through the middle of your worm bed and straight out the bottom. the water in the tube is cool and will help keep your bed cool. the water is contained in the tube so your soil wont get wet. The water that drips out the bottom of the bed will evaporate and also help keep the bed cool. cover your bed with shade. Let me know what you think. total cost is just a couple of dollars for a water cooled worm bed.
This sounds like a great idea for cooling a worm bed/bin. Unfortunately, my AC drain is on the opposite side of the house, but it could work for somebody else. Thanks for the tip.