Red Wiggler Worm farming in the heat.

Written by Matthew on August 11th, 2010

“How hot can my worm composting bin get without killing the red wigglers?”

That is a question I have been getting lately. Worms can actually survive quite high temperatures, but the conditions have to be right. So the answer is complicated, but I think that I can explain to you the problems associated with summer worm bin temperatures and what to do about them. Rest assured that the summer heat will not kill your worms if things are managed properly.

It is my conclusion that it is not the heat itself that kills worms, but instead other conditions that are caused by high temperatures. The primary reason worms might die in the heat is a lack of oxygen. All living things and processes consume oxygen. When food is consumed it takes oxygen to turn it into energy through a process called respiration. Worms are not the only creatures in a bin consuming oxygen but thousands of microscopic life forms as well. So the first thing we should do when the worm bin temperatures start to rise is to reduce the amount of feed going into the worm bin.

So how much and how often do I feed my worms?

The general rule of thumb I use when feeding my worms is well, I don’t really have one. It is really simple actually, start with a pound of food for every pound of worms and feed them every 3 or so days. Do this when it is convenient. If it is easy for you to feed them everyday than that is fine as well, just watch that the bin doesn’t start to get to much food in it and that no smells emanate. Any smell, mold or flies are signs that there is to much food. It is far better to underfeed than to over feed, especially when it is hot. In the heat cut your feeding in half would be a good starting spot.  Although the worms will not grow as fast they will be healthier.

Got worms? Buy here if not. Did you know that the red wiggler worm can consume twice its weight in garbage each week?

Moisture and water is necessary in the worm bin but to much can reduce the amount of oxygen available to the worms. This is due to a couple of reasons. The first one seems obvious, the water reduces available air spaces. Just like plants need good drainage so to due worm bins if they are subject to heavy watering. The second reason is a speculation on my part that to much moisture accelerates the consumption of feed and the composting process further increasing oxygen consumption.

So how wet should my worm bedding be? How much and how often do I water my worms?

General rule of thumb is damp enough so that when a handful is squeezed a drop or two of water comes out. You want the bedding to about as moist as a  wrung out sponge. So extra drainage is important when it is hot. You do not want a soaking wet bedding when it is hot. Watering is important when it is hot because it helps cool, but just be sure it drains well.

  • Keep the worms in the shade
  • Don’t overfeed
  • Well drained bin
  • Screened lid allows for evaporate cooling as opposed to a solid lid

Thanks for reading, now you don’t have to sweat the heat (:


14 Comments so far ↓

  1. Chuck says:

    Thanks for the info Matthew,some really good info as always.


  2. jeanne says:

    I have been reading through your e-mails and haven’t come across a similar problem. I live off the grid and do not have septic. I came across a page on vermicomposting that said the worms could be used for human manure. I have been looking for more info, but have seen nothing specific as what not to do or how to start. We produce a 5 gallon bucket about every 3 days, waste and rice hulls to cover. after 8 years the compost pile is getting pretty big. I would like to use worms to break down the waste faster. Also I worry about having them sent in the mail. I live in Northern Calif. In the coastal mountains It can get pretty hot in the summer into the 3 didgets, in the winter it will get down into the teens. I thought that if I started breaking down the big pile into a new smaller starter pile, but it would not be in a container. Would you follow the same basic steps that you had on your get started page? Thank you jeanne

  3. Diana - Miami Florida says:

    Yes I had a big problem the first of June and lost more than half my worms. I started with one pound, so Im down to a half pound.
    Matthew, what do you think of the wooden bins?
    Oh! Do you know of any worm composters here in south Florida?
    Thanks for all your help, I received my PH testers today in the mail.

  4. Matthew says:

    I don’t have much experience with composting humanure but from what I understand the worms will naturally take hold and multiply in the compost bin in this situation. With a large compost pile the worms can usually migrate to an area which is in temperature range they can stand. And if not the eggs will survive and hatch when conditions are more normal. Shipping is not usually a problem. We ship a lot of boxes each week and rarely have any problem. South Texas during the middle of summer is a slight problem, but otherwise it is not a problem. I would provably use the whole large compost pile as the temperature is likely more stable. Container is not needed at all. The worms can probably make the pile 1/3 the size it is now and make a much more usable product. Starting with a good number of worms will speed the process, but it might be best to buy 2-5# at first and see how things go and then add another amount later if needed.

  5. Judith Coghlan says:

    There is lots of info on production of worms during heat. What do I do in winter to keep them producing and no dormancy? Can they stay outside in a manure pile ( without losing them ) must they be binned and brought indoors? I need more knowledge about winter before I can purchase Please send me some information.

  6. Janis says:

    I have a small worm farm here in South Fla
    I found out the worms prefer from 60 to 75 degrees or something like that, I put my worms in my living room and its been fine. No odor, they dont get loose. They have over populated the thing so I must be doing something right. I have been doing this for 2 years

  7. Matthew says:

    That’s good to hear. Sounds like you are well on your way to being a worm farming pro!

    Sometimes they are a few bumps in the road when learning to raise worms. I had some issues when learning how to raise worms as described here. Can you share any problems you had but eventually overcame? This could help encourage others who are learning.


  8. Matthew says:

    Yes they can be kept outside as long as they are kept above freezing they will survive. As they get use to the worm bin conditions over the winter they will be primed to really take off in early spring. The worms reproduce best as the temperatures start to get warmer in the spring, as the temperatures get hot in the summer they will slow down the reproduction so it is best to get them before it gets to hot.

    Sorry for the delay in responding, for some reason the comment was caught in the spam filter.

  9. Diana says:

    I’ve just started my worm farm and I’m using this site to look for pointers and making sure I’m doing it right. I’m wondering how often I should put new bedding in and how to do this so it doesn’t mix with the food. Thanks!

  10. Matthew says:

    A good trick is to just cover the food with a little paper or other bedding every time you feed. That is all you will need to do.

  11. Mary says:

    Thanks for posting this information about things one can do to reduce the hot temperatures in the worm bin. I started in worm composting this may, and its an adventure, very interesting thing. Today I take the temp. and noticed that it was like 87 farenhit, then checked manually and found that I over fed them with bannanas chunks that were hot, I remove this from the compost and the temp low to 85 degrees. I know its hot but is June and I live in the Caribbean. for your post I realized that I gave them to much food the last time. See? I have a 360 worm factory in the first tray almost with 2,500 red wriglers.

  12. Gene says:


    We are starting up a very large composting project here at the resort hotel I work at in the Caribbean. We are located right on the beach. in consequence we have an abundance of seaweed that is washed ashore everyday. My question is can this seaweed be fed to the worms. Seaweed has always been known to be packed full of vitamins and other healthy resouces but have no idea if good for worms. There might be a salt content problem, however washing it might take care of that. Any thoughts? Thanks.

  13. Matthew says:

    Sounds like a very interesting project. I am thinking that the salt is going to be a problem. Red wiggler worms are very sensitive to salt and will abscond if there is much salt in the worm bin.

    Only thing I can really say is to just give it a try and see, but do the testing on a small scale and for several weeks before going larger with it.

  14. Gene says:

    Thanks for getting back…
    Since I wrote you I’ve done a quite a bit of researching and found several articles saying seaweed can be used but must be soaked and very well rinsed, so I guess I’m going to give it a try. I agree however doing some testing is the smart way to go. Thanks agin for your advice, I’ll let you know how it turns out.

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