Crawl space root cellars

Helloooooooooo,
So yeh. We have a crawl space and we want a root cellar. We live in Red Lodge, MT. It’s underground, somewhat heated because of all the heat making things down there, and so it’s also ventilated. I don’t think there are mice down there but I thought about just setting it all in a tub and making it so no mice could get to it. We don’t need to store a ton of stuff at this point. Should we just try it out with onions and see how long they last?? Any suggestions? Put a thermometer down there and see what the actual temp is? I already have a ton of projects and don’t really feel like making this into another big one. Thanks!

thermometer to start with, probably? bonus points if it’s one that records the lowest temp.

it must be fairly well insulated if it actually feels warm. i assume your lows there in montana are lower than here in western nc, and it definitely freezes in our crawl space when we see temps in the teens or lower.

Yes, sticking a thermometer down there would be a great start.

Ideally, a root cellar should be close to 32F, but not drop below that for ideal vegetable storage. If I was storing canning, I wouldn't risk it that cold as it's one thing for a carrot to freeze and another thing for a glass jar to.
There are veggies - like onions - who like it a bit warmer, so ideal root cellars have colder zones and warmer zones.
You'll likely have more consistent temps on the north wall. My parents house had a walled off area that was insulated from the rest of the basement, but not from the foundation wall and it did the job unless we had a protracted cold snap. You want a quick project, but even recycled bubble wrap draped down to "trap" the cold of a north wall could get you a cool spot without it freezing. Ideally, you would check the temp first thing in the morning for a while to see what the trends are and how it tracks with outdoor temps.

Rats and mice will be attracted to the smell of fruit and veg and they can chew through plastic, so the thicker the better or look for metal buckets/tubs. The tubs themselves need airflow, so consider using hardware cloth to make mouse-proof lids or drill small holes to allow airflow. That said, last year I used buckets with potatoes layered in sawdust inside a broken freezer inside an insulated out-building and they lasted far longer than any other system I've tried in the past. We generally get only a little below freezing weather.

I think it would definitely be possible to do this as a quick project. Friends I know who used to have a crawl space did get a pair of movers dolly's and fashioned a "cart" so they didn't actually have to wreck their knees crawling on concrete.

Throw a thermometer down or just some onions/potatoes and see how it goes, a plastic tub with some ventilation holes sounds a good idea, but watch out for it being chewed through.

I agree with Skandi. It doesn't have to be a big project, and it never hurts to experiment on a small scale. See how it goes. You'll gain useful information either way.