Thermometers and monitoring temperatures in a worm farm – BLOG 021017

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October 2nd, 2017

The Worm Man BLOG

Hi Everyone,

A question that often comes up is what is the temperature range that worms should be kept in. Another common question is then, what sort of thermometer should I buy if I am buying one?

(I’ve included the figures for the most common worm species at the end of this post for your reference.)

Well, it really depends on where and what you are measuring.

For instance:
You may like to measure the bedding temperature of a CFT or a bin.

You may ALSO like to measure the air temperature around your system, so that you can get a feel for what the bedding temperature does in relation to air temperatures. You may also like to measure the temperature IN your house as well as outside.

And for very little money, you can buy a digital thermometer for any of those purposes.


Measuring the air temperature at the location of the worm farm:

I like to measure the temperature of the bedding in my farms – but I also like to monitor the air temperature in the main location of my systems (my shed).

This is so that I can get a feel for how a system is changing temperature compared to the air temperature of the environment. The environment has a huge influence on the temperature of our farms – and also influences how much you can feed.

To monitor temperatures, I generally use a similar unit to the following one (this is an “unbranded” unit, the same as the ones I use, that you will see me using in my Youtube videos and such.)

This is exactly like the one that I use:  (Purchase link –

Thermometer for worm farms

Thermometer for worm farms

The benefits of this one are that:

– it has a neat probe on a wire that is meant to read the “outdoor” temperature – I use that one to read bedding temperatures

– it also reads humidity (how wet the AIR is) – this allows some understanding of if the farm may be drying out, or whether misting water onto the surface of a hot farm will work to cool it

– it has a maximum/minimum temperature reading, so that you know what the temperature got up to or down to while you were away

– it uses “AAA” batteries – they last a LONG time (one of mine has been going for over 2 years!)

– it is easy to read

– mine have been ULTRA reliable


Measuring temperatures in a deep system like a compost pile or wedge – or deeper in a CFT:

To read temps deep in a compost pile, CFT or in the wedge, for instance, it’s easy to make a little piece of heavy wire into a longer probe. That’s what I have done.

You just tape the probe of the thermometer unit to the end of the wire. Then you can (carefully) plunge it into the depths of the bedding/pile to get deeper readings. If you want to be rougher with it, you could also silicone the probe into the end of a piece of conduit – but I haven’t needed to do that.


Measuring the temperature of the environment (air) around your farm or house:

For a thermometer to measure the environment around your system – the air temperature of your location – you could use the ones I mentioned before.

But, if you didn’t want to run the wire outside – or it was a little distance to your farm – you could use something like this one, that has a neat “wireless slave unit”: (Purchase link:

Wireless Thermometer for worm farms

Wireless Thermometer for worm farms


The temperature of your bedding (and the air temperature that contributes to it) are MUCH more important to monitor than pH, which seems to be the thing people fixate on, but is a LOT less necessary.

So – that’s the skinny on thermometers – and measuring the temperature of your worm farms.

Following: details on temperature requirements of the different species:

This information is a guide only.

Worms have been known to get frozen and re-thaw and live. But don’t do that on purpose !

Personally I have found that at around 88-89° F  ( 31-32° C ) that both euros and africans will leave their bedding. Sometimes they mass on the edges or front of a breeding tray – sometimes they will drop to the floor – even in full daylight – to try to find a cooler spot. Reds and blues seem to stay in the bedding and just perish.

Reds (E. fetida / E. andrei)

Min. 38° F            ( 3° C )
Max. 95° F           ( 35° C )
Ideal 70-80° F    ( 21-26° C )

Blues (P. excavatus / P. spenceralia)

Min. 45-50° F        ( 7-10° C )
Max. 90° F              ( 32° C )
Ideal 70-80° F       ( 21-26° C )

Africans (Eudrilus euginae)

Min. 45° F               ( 7° C )
Max. 95° F              ( 35° C )
Ideal 75-82° F       ( 23-27° C )

Euros (E. hortensis)

Min. 38° F          ( 3° C )
Max. 90° F         ( 32° C )
Ideal 60-70°F   ( 15-21° C)


Thanks very much for reading my blog – and HAPPY WORM FARMING !
Brian Donaldson

The Worm Feeding Guide

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