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Harvest Window for Storage Crops

Storage crops are harvested once, and when you pick them largely determines how long they will keep.

What counts as a storage crop?

Onions, garlic, potatoes, winter squash, pumpkins, sweet potatoes, carrots, beets, cabbage and apples are common examples. They are bred or selected to hold quality for weeks or months, but only if they are harvested at the right stage and handled with care.

University of Wisconsin Extension groups crops by the storage conditions they need, such as cold and moist or warm and dry, so it helps to know which group each of your crops falls into before harvest.

If you are unsure which group a crop belongs to, ask your extension office before you plant, because it affects how much space and what kind of storage area you will need.

What plant signs show that onions, garlic and potatoes are ready?

Iowa State University Extension says dry onions are ready when the tops fall over and begin to dry, and garlic when the foliage falls and dries. Potatoes are ready to dig once the vines brown and die. Those signs mean the plant has finished moving energy into the bulb or tuber.

Harvesting early gives thin skins that bruise and rot. Waiting too long in wet weather can invite rot and, for garlic, bulbs that split. Dig on a dry day when you can, and handle gently.

How do you know when winter squash and pumpkins are ready?

The rind is the clue. Iowa State describes winter squash as ready when the rind is hard enough that a fingernail cannot puncture it, and pumpkins when they are a uniform color. Leaving a piece of stem attached helps the fruit keep.

Cut rather than pull, and bring the fruit in ahead of hard frost. Frost damaged fruit does not keep well, so watch the forecast in the weeks before your average first fall frost.

Fruit that is harvested before the rind hardens often does not keep, and tender-rind fruit also stores poorly. A quick fingernail test on a few fruit in the patch gives you a good read on the rest.

What about sweet potatoes and root crops?

Sweet potatoes are usually dug around the time a vine-killing frost arrives, according to Iowa State, and they are sensitive to cold. Dig on a dry day and handle gently, since bruises and cuts invite decay.

Carrots, beets, parsnips and turnips store well in cold, moist conditions. Several can stay in the ground for a while and be pulled as needed, though a hard freeze can damage them in cold regions. Your extension office can tell you how long you can leave them.

Why does curing matter, and who should you ask?

Several crops, including onions, potatoes, sweet potatoes and winter squash, are cured after harvest to heal minor damage and toughen skins. The conditions differ by crop, and some squash types are not cured at all. Rather than guess, follow the curing and storage guidance from your state extension service.

Because storage and preservation are food safety topics, we do not give specific temperatures or times here. The National Center for Home Food Preservation and your extension office publish tested guidance.

How do you build a harvest window plan?

Work backward from your average first fall frost. Ask which crops must be in before then, which can wait, and how many days of good weather you need to bring them in. Wet autumns shrink the window, so start early if the crop is ready.

Keep notes: date harvested, weather, and how well each crop kept. At the end of the storage season, look back and adjust. If a crop failed early, note the harvest date and handling and compare it with the next year.

What mistakes cause the most losses?

Digging too early, digging in wet soil, rough handling, and mixing crops that need different storage conditions are common. Storing damaged produce with sound produce also spreads rot. Sort carefully and use the damaged items first.

A small amount of care at harvest is the cheapest way to improve how long your crop keeps.

Another common problem is storing crops that give off ripening gases next to ones that are sensitive to them. Apples and other ripening fruit, for example, are best kept apart from potatoes, according to Iowa State. Plan your storage space with that in mind before harvest begins.

Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.

More in Harvest, Storage & Post-Harvest Timing

• Harvest Timing for Root Crops
• Harvest Timing for Leafy Greens
• Harvest Timing for Fruit Vegetables
• Harvest Timing for Brassicas
• Harvest Timing for Bulb Crops
• Harvest Timing for Winter Squash and Pumpkins