Anyone measuring soil temperature?

It’s only 42 this morning but we’ve been warm the last two weeks, roughly 80/50. I measured 4 inch soil temperature at sunset yesterday and at sunrise this morning. This is what I found.

Outside shaded all day: 62 at sunset / 58 at sunrise
Outside mulched in the sun: 73/64
Outside under black fabric for melons: 83/74
In the greenhouse: 83/78

Outside black fabric increased soil temperature by 10F over mulched.

There was less difference than I expected between outside with black fabric and inside the greenhouse. The GH has been about 95 high and 60 low for about two months.

Still if the GH is about 80F soil temperature that should be good for mango and my new Medjool date tree.


What tool do you use for that? I’ve thought about getting soil temperature probes for continuous monitoring, but couldn’t settle on what kind to get because nothing seemed compatible with my DIY air temperature monitors (raspberry pi computers). A good quality manual option might be a good alternative to continuous monitoring I guess.

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I use a meat temperature probe that’s $12 on Amazon. It has a steel probe about 4-5 inches long and is very accurate and quickly responsive. TEMOLA Meat Thermometer, Instant Read Food Thermometer with LCD Backlight Calibration, Waterproof Ultra Fast Digital Cooking Thermometer for Candy Deep Fry Liquids Beef Kitchen Baking Smoker Grill BBQ: Home & Kitchenemphasized text

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Aha! Not sure why that didn’t occur to me, that’s a good repurposing. I think I’ve got two meat thermometers already, one could even be dedicated to the greenhouse tool bin.

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I measure and log 4” and 8” temps with my weather station software. I also have a Watermark moisture sensor in there as well.

We’ve had 2” of rain so far today so the ground is pretty much saturated. It’s reading 11cb, but it should be closer to the fully saturated value of 0cb.

4” and 8” depths were 49° at midnight, but with the cold rain they’ve dropped to 46° and 47° respectively.


I have a raspberry pi sitting around and I’d like to monitor the temperature. What is your setup like?

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What would the reason for measuring soil temperature be? I got a meter for ph, moisture and light that was 9 dollars but found the ground soil bent and nearly broke the metal on it after just a few times. It has sat in a drawer for 3 years after that. With knowing if the ground is able to be dug for perennials I can typically see from plants around me in the neighborhood. When soil temps rise the Crocus are the first plants to come up. It is then fallowed by the other bulbs like tulip or daffodils. They will be fallowed by the trees and bushes turning green or turning white on the buds. I am still unclear how some bud as I have not been paying to our apricot in the back and have not seen the bud swell on my recent apricots but know my hazelnut, plums, cherries and pears turn green while my apples and peaches get a almost fuzzy bud when the bud swells. My nuts like pecan are different as they seem to have an apple or peach swell but seem to get bigger. Then locals just know not to plant annuals until Memorial Day. People debate that you can start annuals outside on mothers day but there is often a chance of frost that will not kill or affect perennial crops but will kill annuals off until Memorial Day.

I have a Davis Vantage Pro2 weather station with the soil station add-on with soil temp, soil moisture, and leaf wetness. If you’re good with the pi you should have no problem setting up a probe and moisture sensor. The Davis soil temp probes are in a stainless steel housing…just gotta make sure you install them horizontally at the desired level and not vertically.

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I would love to measure my soil temperature but it is hard to break through the ice even an inch. For the last couple of days I have been scraping my compost pile with a rake so I can get some for a potting mix. At least it being dark it soaks up sunlight better than the soil.

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I have a soil temp / probe type thermometer…

Morels start fruiting at 52 deg ground temp.

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We had a very cold day yesterday high in the 50s and 8 hrs last night below 40. That dropped soil temperature outside under black fabric from 74 to 66. Only an 8 degree drop after 36 hrs of cold. And still good for melons.

In the greenhouse this morning it was 77 rather than 78 yesterday. I like that and I think my plants will also.