How do you measure soil temperature?

[Lavender2]

Lavender, I know that's the truth for my soil too! I can be working in town for two weeks on clear mostly thawed ground, while here I still have mounds of snow.

Since there is such a wide variation in optimum soil temps for seed germination, from onions, lettuce, peas to the really warm soil needs of peppers I like to use a thermometer.

Yeah, I know, who starts their peppers in the ground anyway, besides Bay I mean?

Oh jeez, I thought I was alone in my club...
My mom lives about 5 miles away, when her hostas are poking through I'm just starting to see grass!

For those of you who can sit on the ground with your trousers down on a sunny day ... think about this ... and I could punch myself for looking this up!..

Last year the frost depth here, on this date was 25" (already up from a max depth of 40"). Right now if you dug a hole 60" - FIVE FEET! - you would still freeze your butt! ...

 

[Nyboy]

I also keep a eye on sprng bulbs.

 

[HEChicken]

I also keep a eye on sprng bulbs.

How do you use the info you get from bulbs coming up? I.e., does that mean you start planting immediately, a week later, a month?

 

[PhilaGardener]

Red, please be very careful with that old mercury thermometer. Mercury is extremely toxic and persistent in the environment as a contaminant. If that breaks in your garden, you would have a serious problem that could contaminate your soil and groundwater.

Anyone still using mercury thermometers (filled with silvery liquid) should consider turning them in at a municipal toxic waste collection day and replacing them with newer ones filled with an alcohol solution (usually . . . RED ).

 

[HEChicken]

Oh, I only wish we could still get the mercury ones - I'd buy a bundle of them! I've tried numerous of the newer ones and they are terribly inaccurate. I've never yet found one that had the slightest chance of giving me an accurate reading.

 

[Ridgerunner]

I haven't tried the spirit ones either, but have you tried calibrating them? Mix ice with water until you're sure it has stabilized at freezing, then see how far the reading is off. If it reads 34, just subtract 2 degrees from what you are seeing. Doing that at boiling is probably off the scale. Or take one you trust, like a medical thermometer, and see what the difference is.

Or are you talking about repeatability, where one time it might read 34 at freezing and the next time read 29, also at freezing. I can't help with that.

 

[Smart Red]

All this talk about how to measure soil temps. How about ways to raise the soil temperature?

With my raised beds, I have laid black plastic down on the soil and put a layer of Vis-Screen (plastic) over the sides of the bed. In a few sunny days, the temperature in the bed went up 20 degrees (F) higher than those beds not covered. I could plant earlier and leave the plastic over the sides until the plants were up for cool night protection.

While I'd never do it with the whole bed, it can be useful to get a head start with a few long season veggies. Especially those I can keep covered with hot caps until the weather is warm enough.

 

[HEChicken]

I haven't tried the spirit ones either, but have you tried calibrating them? Mix ice with water until you're sure it has stabilized at freezing, then see how far the reading is off. If it reads 34, just subtract 2 degrees from what you are seeing. Doing that at boiling is probably off the scale. Or take one you trust, like a medical thermometer, and see what the difference is.

Or are you talking about repeatability, where one time it might read 34 at freezing and the next time read 29, also at freezing. I can't help with that.

The main problem I had with the spirit ones is that whatever it reads when I pull it out of the package….never changes. Put it in hot water, put it in cold water, "shake" it (like the mercury therms) - nothing. It reads what it reads without changing (and this is multiple of them, not just one dud) and therefore it seems pointless to try to use it to take the temperature of a mere human.

 

[Smart Red]

Red, please be very careful with that old mercury thermometer. Mercury is extremely toxic and persistent in the environment as a contaminant. If that breaks in your garden, you would have a serious problem that could contaminate your soil and groundwater.(usually . . . RED ).

So noted and thank you! I honestly never did think about it polluting my soil.

I keep in in its storage case in a secure spot out of the reach of the Grands and seldom use it after the warmth of spring seems ready to stay. Being a heavier, lab-type thermometer carefully used, I don't foresee any problem.

 

[baymule]

I have never taken the soil temp.....in the winter it's cold. In the summer......well......I just figure the soil has a FEVER because it's so danged hot. Sitting my bare butt in the dirt? I live on a busy street.......car wrecks......blinded people.......police station a few blocks away......probably not a good idea....