Can You Store Onions and Potatoes Together?

The familiar onion-and-potato basket asks two different crops to accept the same conditions. Iowa State recommends 90–95% relative humidity for cured potatoes but only 65–70% for cured onions. That gap matters: potatoes lose moisture in overly dry air, while onions are more likely to decay when the air around them stays too damp.

There is also a direct compatibility warning. Iowa State's AnswerLine says onions produce ethylene that can cause potatoes to spoil prematurely and that the high moisture content of potatoes can make onions brown and rot. Illinois Extension likewise advises storing them separately because onion ethylene can encourage potato sprouting.

For homegrown potatoes, cure sound tubers first. Iowa State recommends two weeks at 50–60°F and 85–90% relative humidity so minor cuts can heal and skins can thicken. Then move them into a dark, ventilated container; light causes greening.

Extension recommendations vary slightly because cooking use and household storage spaces differ. Iowa State gives an ideal long-storage target of 40°F and 90–95% relative humidity. Iowa State AnswerLine uses a practical home range of 45–50°F and warns that refrigerator temperatures can make potatoes sweeter and cause dark cooking. The constants are more useful than a single perfect number: keep potatoes cool, dark, ventilated, unwashed, and away from onions and ripening fruit.

Onions must be thoroughly cured before they go into storage. Iowa State recommends two to three weeks in a warm, dry, well-ventilated place, followed by 32–40°F and 65–70% relative humidity. Use a mesh bag, wire basket, crate, or braided dry tops so air can circulate.

Discard decaying bulbs and use thick-necked onions promptly. Never let an unheated garage fall below freezing around the crop, and do not seal onions in a plastic tote or bag. A dry, breathable onion zone is the opposite of the humid environment potatoes tolerate best.

You do not need two rooms. Use two containers in the coolest dark cupboard, closet, basement corner, or insulated garage zone that remains above freezing. Put potatoes in the darker, slightly more humid location and onions in the drier, breezier location. Different shelves are better than side-by-side bins, and one shared closed cabinet is less useful if it traps moisture.

Buy smaller quantities if your home stays warm. At room temperature, potatoes may last only about two weeks, according to Iowa State AnswerLine. A modest amount that you check weekly wastes less money than a large bargain bag that sprouts or rots before you can use it.

Properly cured garlic has storage needs similar to onions. Iowa State recommends 32–40°F and 65–70% relative humidity for both crops, so they can occupy the same cool, dry area in separate breathable containers. Keep high-humidity roots such as carrots in another zone.

Do not treat every cool-storage crop as interchangeable. Apples and other ripening fruit release ethylene that encourages potato sprouting, while winter squash prefers a warmer, drier range. The storage-compatibility table on the Garden & Homestead page gives a quick starting point for these common pairings.

No. Separating onions and potatoes is general produce-storage guidance based on humidity, light, and plant physiology; it is not an exclusively Amish custom. The Young Center notes substantial variation among Amish affiliations and local church districts, including differences in accepted technologies.

This guide is Amish-inspired only in the broad plain-living goal of keeping a harvest useful with simple equipment. Its specific storage targets come from university Extension sources, not from a claim about universal Amish practice.