Best compost thermometers: reviews & buyer’s guide

Did you know that Shakespeare wrote about compost? In a conversation with his mother, Hamlet says: “And do not spread the compost on the weeds to make them ranker.” Now how that relates to compost thermometers, I’m not entirely sure…but if Shakespeare was a gardener, being the rather intelligent chap I’m sure he was, he’d definitely have one.

Compost thermometers are useful little things. They can assist with understanding, turning and moderating your pile. In this little guide I want to offer some general buying advice and also take a look at some of the better-known models on the market. Let’s dig in.

The short version: best compost thermometers

Click here to jump to our selection of some of the best compost thermometers from around the web.

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What is a compost thermometer?

A compost thermometer is simply a thermometer used to measure the temperature of the middle-area of compost heap. The probe needs to be relatively long  (usually around 20 inches) to reach the center and it also needs to be made to withstand moisture and creepy crawlies. Generally speaking, temperature is used to indicate when to turn a pile and to ensure that it has maintained a high temperature long enough for weeds and diseases to die.

REOTemp Compost Thermometer
Colour indicators help you keep within a specific temperature range.

How often should you turn?

Ideally, you want to turn your pile after each burst of heat. Most gardeners work on the basis of turning every few days and, whilst this does work, it’s far from a scientific approach. Compost should be turned when it reaches between 140 and 150 degrees, in the thermophilic stage. It should then be left until there is a rise in temperature again (usually five to seven days).

This information, of course, is only applicable to “hot piles”. Cold composting follows a different process and it’s not usual to use a thermometer.

Features to look for in a compost thermometer

  • Measurement units – If you live in America then you’ll likely want the readings to be in Fahrenheit (°F). Alternatively, those in the UK will want a thermometer that measures in Celsius (°C). You can opt for either or go for a model that has a dual scale (one is included in the selections below).
  • Probe length – Ideally, you want to measure the temperature near to the center of your heap, so the bigger your heap the longer you’ll need your probe to be.
  • Rust-proof materials – Because thermometers tend to be left in compost piles for long periods, it’s important that they’re made from rust-proof materials and sealed very tightly to prevent the glass from misting up.

Best compost thermometers: Some picks from around the web

***Full Disclosure – Where appropriate, I’ve linked product images to commercial sites and Amazon (see Amazon Disclosure). If you buy from these sites, I earn a small affiliate fee, which helps me keep Urban Turnip going.***

REOTemp Compost Thermometer

REOTemp Compost Thermometer

This thermometer from REOTemp is a safe bet for anybody looking for reliability. The consensus from reviewers is that it lasts a long time, is durable and will not be harmed by the moisture and creepy crawlies in your compost pile. It’s hermetically sealed (meaning that it is airtight), so it won’t cloud up if it’s left for long periods or overnight. The probe is also a little thicker than usual to add extra durability.

The colour display – indicating steady, active and hot – is another bonus and will help you maintain your pile in an ideal range. Overall it’s a very well-made and well-priced product and a great option if you’re looking for a standard model.

REOTemp Heavy Duty Thermometer

REOTemp Industrial Thermometer

Another entry from REOTemp! This industrial-grade thermometer is for people who want an absolutely top-notch tool that will last indefinitely. This one has a 36-inch stem (so is suitable for large piles) but the same model is available in a range of longer lengths. The diameter of the stem is 5/16 in. wide (for extra durability).

Like the piece above it’s hermetically sealed to keep out moisture. Importantly, it also has a dual temperature scale, so you can read measurements in both celsius and fahrenheit. It comes with a 1-year warranty. If you want a really high-quality piece of equipment, especially if you’re working in an industrial setting, then this is the one to go with.

Ecocycle Thermometer

Compost Thermometer

I’ve included this thermometer from Eco-cycle because I love the clean, simple dial design. It also has all the features you would expect in a high-quality model. The stem is 20 in. long and the dial is hermetically sealed to prevent fogging. It’s worth noting that the stem is also slightly thicker than typical models, so there’s an added bit of durability too.

Let us know your thoughts! Leave a comment below!

What are your thoughts? Have you tried any of the picks in this article? Leave a comment below and let me know!

Image credit: Mackenzie

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