A cold-storage room for root crops and winter squash needs ventilated bins or slatted crates, shelving that handles damp, thermometers at more than one height, a hygrometer, and screened vents that keep rodents out. That is the equipment list. The harder part is the target: published extension guides give different temperature and humidity numbers for the same crops, so the best buy is instruments that read accurately, not a promise that one number is right.
This guide is for long storage across the winter. It is not about short-term cooling after harvest, which is a different job covered in the vented crate guide.
What long storage asks of the gear
Short-term cooling pulls heat out of a harvest quickly. Long storage holds a steady, modest condition for months, and the gear has to cope with damp, slow air movement and the occasional check. That changes what you buy. You want containers that let air reach the crop, shelving that will not rot or rust, and instruments you can read at a glance.
Also, one room rarely suits every crop. Roots like cold and damp, onions and garlic like it drier, and winter squash sits in a warmer range. Plan separate spots, even if that only means a shelf near the door for one group and a lower shelf for another.
Where the published numbers disagree
Three extension sources cover this topic, and they do not match. The University of Minnesota Extension lists crop-by-crop storage conditions. The University of Saskatchewan's gardening pages give ranges for home cold storage. University of Alaska Fairbanks Cooperative Extension gives a general cellar humidity range and says squash-family crops and onions prefer dry conditions.
| Crop | University of Minnesota Extension | University of Saskatchewan |
|---|---|---|
| Carrots, beets | 32 F, 95% relative humidity | Just above 32 F up to 40 F, 90 to 95% relative humidity |
| Potatoes | 40 to 50 F, 95% relative humidity | 38 to 40 F, 85 to 90% relative humidity |
| Onions | 40 F, 50% relative humidity | 32 to 40 F, 70 to 75% relative humidity, dry |
| Garlic | 40 F, 60% relative humidity | 32 to 60 F, 60 to 70% relative humidity, dry |
| Winter squash | About 50 to 54 F by type, 50% relative humidity | 50 to 55 F, 85 to 95% relative humidity |
Winter squash humidity is the clearest conflict, with one source at about 50% and the other at 85 to 95%. Minnesota also notes that its shelf-life figures assume ideal conditions and may run shorter in practice. The practical lesson is to use your own state extension's figures for your crop and variety, check them against the buyer if you sell, and let accurate instruments tell you what your room is doing. This guide does not pick a winner.
Containers and shelving
The Saskatchewan pages describe several container styles, and they map neatly to gear.
- Slatted crates, ventilated bins and shallow boxes. Potatoes do well in large, shallow bins or boxes. Stackable ventilated bins work if you leave gaps for air. The stackable tote guide covers footprint and stacking, and the vented crate guide explains vent styles.
- Pails, bins or crates with a damp packing layer. For cold, damp roots, the pages suggest clean pails, plastic bins, coolers or crates packed with slightly damp sphagnum moss, peat, sawdust or sand, with the bottom layer kept thin so water does not collect. Check that your container material and packing media suit food use.
- Perforated food-grade bags. Roots can go in clear food-grade plastic bags with holes punched in, closed with clips or ties. Avoid black garbage bags and bags that held meat or fish.
- Mesh bags, baskets and slatted boxes. Onions and garlic need dry storage with good airflow, so avoid piling them high.
- Open shelves. Winter squash should sit on a shelf, not touching each other and not wrapped in plastic.
For shelving, look for materials that handle damp: coated or plated steel, plastic or sealed wood. Bare steel can rust in a damp cellar. Check the listed load capacity for the weight of full bins, and keep the shelving off the floor so air moves underneath. A used shelf in good condition is a sensible buy; avoid any with cracked welds or bent uprights.
Search by category and compare vent openings, stackability and listed load rating. Used shelving and crates are worth comparing, but check for rust, cracks and odor.
Thermometers and hygrometers
The extension pages agree that temperature varies through a room. UAF says to place thermometers throughout the cellar because warm air rises and the top runs warmer. Saskatchewan says cold air sinks, so floors are often colder than higher shelves. Both point to the same gear decision: buy more than one thermometer, and place them at different heights and near the door and walls.
- Min-max thermometers record the lowest and highest temperature since the last reset. They show what happened overnight when you were not there.
- A hygrometer reads relative humidity. Saskatchewan notes that it is not essential if you store crops correctly, but when sources disagree, a reading is more useful than a guess. Check the stated accuracy and how to calibrate.
- A data logger keeps a record, which helps you see slow trends. See the data logger guide and the hygrometer guide for what to look at. Check the operating range, since cellars can be cold and damp.
Compare the stated measurement range, accuracy and how the unit handles damp. Used instruments can drift, so a new one is often the safer buy for a reading you rely on.
Vents, screens and airflow
UAF notes that ventilation helps control temperature and humidity and can remove excess moisture that encourages mold, and says a ventilation system should be screened to keep rodents out. Saskatchewan adds that cellars need insulation so they do not freeze, plus ventilation for air circulation and temperature control. In equipment terms:
- Screened vent covers or hardware cloth for openings. Choose a material that rodents cannot chew through and that does not rust away in damp.
- A small fan for moving air when you need it, rather than running it constantly. The circulation fan guide covers what to check. Any heater or electrical equipment in a cellar should be used according to its manual and local code.
- Door gaskets or sweeps, if your door lets cold air or pests in.
Humidity is also affected by how full the room is. UAF says a small, full cellar holds humidity better than a large, empty one, and that a concrete or wood floor may need pans of water. These are cellar-specific points, so treat them as notes for the case where your room is dry.
Layout, crop mixing and checks
- Keep fruit away from vegetables. Saskatchewan says apples give off ethylene gas, which makes vegetables ripen faster, so give fruit its own space.
- Keep potatoes dark. Saskatchewan notes this prevents greening, so cover bins or use opaque containers.
- Check regularly. Look at onions and garlic often and remove any that are moldy. Check potatoes often, since excess moisture leads to rot. Remove soft or rotting produce promptly.
- Curing comes first. Minnesota says onions and garlic are cured until the necks are dry, winter squash until nicks have scabbed, and potatoes are stored unwashed after curing. A cellar is for storage, not for finishing wet crops.
Frequently asked questions
What containers work best for root crop storage?
Ventilated bins and slatted crates for general use, shallow bins for potatoes, mesh bags or slatted boxes for onions and garlic, and open shelves for squash. For cold, damp roots, bins with a damp packing layer are described by extension sources.
Do I need a hygrometer in a root cellar?
Not strictly, according to one university page, but sources disagree on humidity targets and a reading beats a guess. Check the stated range and accuracy before buying.
Why do sources give different humidity numbers for squash and onions?
Published guides differ. One lists winter squash at about 50% relative humidity, while another lists 85 to 95%. Follow your own state extension service and your buyer's requirements.
Can I store apples with root vegetables?
Extension guidance advises keeping fruit such as apples away from vegetables, because apples give off ethylene gas that makes vegetables ripen faster.
How do I keep rodents out of a cellar vent?
Cover openings with screening or hardware cloth, as one extension page advises, and check it each season for gaps and damage.
Sources and verification
Storage conditions, container styles, thermometer placement, vent screening and crop-mixing points come from the pages below, read in October 2026. Figures are quoted as each source lists them, attributed by name, and they disagree in places. No other numbers are given; confirm targets with your own state extension service.
- University of Minnesota Extension, Postharvest handling of fruit and vegetable crops in Minnesota: crop table of temperature and humidity, curing notes.
- University of Alaska Fairbanks Cooperative Extension, Vegetable Storage in Root Cellars: ventilation, screened vents, thermometer placement, humidity notes.
- University of Saskatchewan, Cold storage of root crops, cole crops, winter squash, onions and garlic: containers, packing media, mesh bags, crop separation, checks.