As gardening grows in popularity, people are figuring out all sorts of clever ways to get their homegrown vegetables to keep through the winter. Now that root cellars have become a rarity, many companies offer a range of storage tools and other items that can help. But creating the perfect storage environment for a particular crop is only half the battle—they have to be cured properly too, if they’re going to store for any length of time. Here are our curing tips for the crops that need it.


Onions from the High Mowing Trials field curing in the greenhouse

Onions for storage have a unique signal to show that they’re ready to harvest: their tops will start to dry out and flop over. Some varieties, like Cabernet F1, will continue growing after this happens. But for most varieties, the necks are crimped when the tops fall, preventing further photosynthesis and growth. These onions should be pulled up for curing.

Onions can be cured in a number of different ways, but regardless of the method you choose, the principle is the same: they need 1-2 weeks of dry, warm conditions for the necks to dry down and the skins to become papery. You can use this test to see if your onions have finished curing: cut the top off a large onion about 1” from the bulb. If you see any green, they need more time. If the neck is completely dry with no green, your onions are fully cured.

Here are several techniques you can use for curing onions in different environments:

  • If the weather is dry and there is no threat of frost, simply pull onions and lay them down in the field to “sun-cure” for 3-5 days
  • In a warm greenhouse or hoophouse, ideally with a daytime temperature around 80-90ºF and humidity around 80%, lay onions out in a single layer on wire racks for two weeks. Check them every few days and cull any bulbs that have spoiled.
  • Onions can also be cured in a single layer on a clean surface in a shed, barn, loft, attic, garage, sunroom or under a covered porch as long as there is good ventilation and no risk of frost for at least 2 weeks

Once your onions are cured, clip the tops 1” from the bulbs and store in baskets or crates (to ensure good air circulation) in an area that is consistently 35-40ºF and 65-75% humidity.


Freshly harvested potatoes ready for curing at High Ledge Farm

Potatoes need curing too, though many people don’t realize it. Fortunately curing them is really easy. Once the potato foliage has turned brown and died back, leave the tubers in the ground for another two weeks to allow their skins to “set”. This is when the skin thickens and forms a strong protective barrier that prevents the tubers from spoiling.

After the two weeks are up, harvest the potatoes and gently brush the soil off. Now it’s time to cure them for a week to 10 days in a dark, well-ventilated area with high humidity. Simply put them in open paper bags, crates or cardboard boxes in a cool, dark place such as a garage or basement so that their skins can thoroughly dry. When the curing period is up, cull any green, injured or diseased tubers before storing for the winter in a dark, humid environment around 40-45ºF.


A coldframe, like this one at High Mowing, is excellent for curing winter squash and pumpkins

Winter Squash should be harvested before a heavy frost, usually when most foliage has died back, the stem is becoming dry and brown, and you cannot easily indent the skin with a fingernail. They can generally handle one or two light frosts, but it’s best to cover them or bring them in when cold temperatures are predicted, since multiple nights below 50ºF can reduce their storage life. Always leave at least 1” of stem attached to each squash, since short, broken or missing stems (as well as injured fruits) mean reduced storage life.

Much like onions, winter squash can be stored in several ways, but they generally need about one week of warm, dry conditions with good ventilation for their skins to dry and harden. The sole exception is acorn squash, which should be immediately put in cold storage after harvest. Try any of the following environments for curing everything from butternuts to pumpkins:

  • If the weather is dry, leave fruits in the sun for 5-7 days, covering in the evening if frost is predicted (a coldframe on pallets is excellent for this purpose)
  • Fruits can be cured in a greenhouse at 80-90ºF with good ventilation for 3-5 days
  • Alternatively, a warm, sunny place such as a sunroom, south facing window or loft inside the house is also suitable

Store cured squashes in a cool place around 50-60ºF with good ventilation (entryways, mudrooms, basements and bulkheads can often provide the cooler temperatures preferred by winter squashes.)

Other crops can store well too, but don’t require any curing. These crops include dry beans, beets, carrots, Brussels sprouts, cabbage, radicchio, kohlrabi, leeks, melons and watermelons, radishes and turnips. And certain cold-hardy crops such as Brussels sprouts, cabbage and leeks will actually improve in flavor and sweetness after a light frost or two.