Vermicomposting in Arizona Heat

Question from John:

I live in Mesa Arizona and I’m not looking forward to the Arizona heat
which will reach 115 degrees. Last year I lost all my worms when a
worm dealer said just keep them in the shade. Do you have any good
ideas to keep them alive.

Hi John,

Vermicomposting in extremely hot/dry locations can definitely be a challenge, to say the least. Any supplier telling you simply to “put them in the shade” strikes me as someone more interested in selling worms than seeing their customers succeed! Yikes!

Shade is obviously a vitally important first step – but some additional measures will almost certainly be required.

One strategy that may help is partial or complete burial of the system. The further down in the soil you can dig the more moderate the temperatures will likely be. What I might try is using a half- or three-quarters-buried wooden bin with some absorbent material(s) – like burlap or even old sheets – sitting over top (but inside the bin). If you keep these materials moist (without flooding the system every time you wet) there will likely be a nice evaporative-cooling effect. The zone down below the soil would most likely remain in a temp range the worms can handle.

A somewhat similar idea I learned from my friend, George Mingin, is to drape wet sheets over top of your beds (again, a system with excellent air flow would be important here) and to point a fan towards them (obviously would only make sense in a garage or shed).

A more environmentally-unfriendly approach might involve rotating frozen water bottles between a freezer and the bed(s). If you kept them wrapped in the burlap or sheets that could help to extend the melting period – and the condensation moisture would likely help to keep the cover materials damp as well.

Hope this helps!

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    • Damon D
    • January 26, 2014

    I deal w temps in upper 90’s-low 100’s in California desert. I’ve had success using reflective paneling from local hardware store. They sell it in big rolls. Stapled it to all sides of my wooden bins. Also built a PVC frame around bins and attached it to that as well. It made a huge difference and the sun was no longer a problem.

    • John W.
    • January 28, 2014

    I brought my Worm Inn and Worm Factory inside of my office. I put it in the closet and nobody knows its there thanks to the zero smell coming from it.

    • Matthew F
    • February 3, 2014

    I also live in Phoenix and have been fairly successful over the last couple years with no vermicide in spite of our horrendous summers. I have used both an indoor and outdoor bins, and the simplest solution would be to bring the bin indoors for at least the hot summer months. An alternative and/or addition to using frozen water bottles should you decide to keep the bin outdoors, would be to freeze your food scraps prior to adding them to the bin. This not only helps to cool the bin down but once the food has thawed it is easier for the worms to break down, as well as killing any fruit fly eggs that might be on the produce. I personally keep my bin indoors year round now, I never have odors or pests and it seems like the best way to keep worms thriving.

    • Jeb C.
    • February 5, 2014

    Yeah, also in Mesa AZ, keeping them in a shaded garage didn’t pan out for me over the summer. Up to 100 degrees was fine, but past that, some of the little guys would start roaming (and dying out / drying out on the garage floor). I suspect I may not have lost the entire population if I let them tough it out as the contents of the 35 gal tote never felt too hot when I stuck my hand in there, but I caved and brought them inside.

    Outside I’ve had worms are in a flood / drain aquaponics system as well as a soil based wicking bed, and those guys do just fine through the summer. They both get sun too, but the worms seem to do all right in them.

    • Tom Bergstrand
    • February 7, 2014

    We have hot weather here in Kingman so one liter bottles of water kept in the freezer get added every day.

    • Yvonne
    • March 2, 2014

    I, too, live in Mesa. I moved here from California with a bin of worms in July last year. I put the worms directly on the ground in the garden near the roots of a large bush with a drip system nearby. They ultimately succumbed after a month or two when the soil got too dry, but it did show that they were able to tolerate ~110+F weather out of direct sunlight.
    I’m thinking of buying or building a garden tower planter, and putting worms in the center composting tube (see link below). I’m planning to keep it outside in partial shade (back patio, which has a roof). My hope is that the plants and the dirt will provide enough insulation from any direct sun that they’ll survive the summers, and the whole system is supposed to be pretty water efficient, which is an important consideration for a region that’s supposed to run out of water soon. Has anyone else tried this yet? I’d love to know if it worked.

    • MurphyTalbot
    • April 14, 2014

    I am in Chandler, with 3 very large Vermiposting bins that are cut down plastic city trash bins with holes in them They are semi buried and I have great success. I am an avid gardener with 3 gardens a year in raised beds and my worms eat every bit of what is put in the bins. The bins are in shade and kept moist. My raised gardens are thick with worms transfered out of the bins over the years. They do go down deep during the summer. I have been doing this for 10 years.

    • Ray White
    • June 22, 2014

    I’m just getting started planning for vermicomposting and have a few questions.

    1. How deep do my raised beds have to be to allow the worms to survive? Mine are 12″ filled with good quality garden soil and watered mostly by 1/2″ drip irrigation hose (with an occasional wetting from above with a spray head. Only a couple of my 5, 16′ x 4′ raised beds get any shade other than that supplied by the plants I’m growing in them. I could do shade cloth but don’t want to harm vegetable production.

    2. Who do I buy worms from here in Kingman?

  1. A student of mine had good luck with a buried system in Skull Valley, AZ (elevation 4,200 ft). Dig deep enough and you get a root cellar effect. It retained moisture surprisingly well with a loose fitting plastic lined cover so that moisture generated from the metabolic activity condensed and rained back down.

    You can see a report from her project here:

    The Prescott, AZ Farmer’s Market has a great vermicomposting booth but for some reason it is not listed on their website. Patrick sells worms and they are nice quality (I have some in my current bin). He has an outdoor horse manure based system in full sun (windrows). Granted it is high elevation in Prescott (5 – 6,000 ft), but I was amazed. The windrows formed a dry hot crust, but inside the pile it was moist and cool.

    Tucson has some great vermicomposting businesses too:

    • Bentley
    • July 15, 2014

    Thanks for popping by and sharing your thoughts (and interesting resources/info – great stuff as always), Allison! We definitely need to get caught up some time.

    Nice so see one of my Worm Farming Alliance members (Linda Leigh) getting a bit of free press as well!

    • Neil
    • January 12, 2015

    I live in Las Vegas. Fortunately for me there’s a local hobbyist from whom I got my worms. His worms have been acclimated to our harsh temps and can survive outside with no extreme measures, in the shade.

    • Sondra
    • February 25, 2015

    I am also in the East Valley Phoenix area. I’m wondering if anyone has considered getting a used refrigerator (apartment complexes replace old ones on a regular basis and sell them for dirt cheap). You could insulate the worm bin so the worms don’t get too cold and put the bin in the fridge during the hot part of the day….. Just an idea.

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