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Harvest Timing for Bulb Crops

Onions, garlic and shallots tell you when they are done, and what they say is written in the tops. Your job is to read the tops and pick a dry day.

What signs show bulbs are ready?

Iowa State University Extension says dry onions are ready when the tops fall over and begin to dry. Garlic is ready when the foliage falls over and dries, or just before the first frost. Shallots behave much like onions, and leeks are different, since they can be picked at many sizes.

The tops fall because the plant has finished sending energy into the bulb. Pulling before that point gives smaller bulbs with thick, wet necks that do not keep well.

Shallots and multiplier onions give the same signal, though they often mature a little earlier than large bulbing onions. Keep a few rows of each type and note which one falls over first each year, so you can stagger the work.

What about garlic specifically?

Garlic has a narrow window. If you wait until all the leaves are brown, the wrappers may break down and the cloves can separate, which hurts storage. If you pull too soon, the heads are small and the wrappers thin.

Many growers dig a test bulb or two when the lower leaves begin to brown and check how well the wrappers have formed. Your extension office can tell you how many green leaves to look for with the types grown in your area.

How do weather and soil affect the harvest?

Dry weather is ideal. Bulbs lifted in wet conditions carry moisture that invites rot, and the tops take longer to cure. If heavy rain is coming and the crop is ready, lift early and cure under cover.

Loosen soil with a fork instead of pulling by the tops, which can tear necks. Avoid bruising, since damaged bulbs rot first.

Late nitrogen and heavy watering near maturity can keep tops green and delay fall-over. Use a soil test and local recommendations for fertilizer timing, since nutrient management rules and advice vary by state, and ease off irrigation as the crop matures, within local water rules.

What happens right after lifting?

Bulbs need to be cured, which means drying the outer skins and necks in a warm, shaded, well ventilated place. Iowa State describes curing onions until the tops and necks are thoroughly dry. Keep them out of direct sun, which can scald, and out of rain.

Exact curing and storage conditions differ among crops and climates, so we do not list temperatures or times here. Follow your extension service and tested guidance, and check the National Center for Home Food Preservation for preservation methods.

How do you plan around day length and variety?

Onions respond to day length, and varieties are grouped by the day length they need to form bulbs. Planting a type not suited to your latitude gives poor results. Ask your extension office which types suit your area and when to plant.

Garlic types differ too. Hardneck and softneck types mature at different times and store differently. Planting dates are tied to fall frost timing in many regions, so use your local frost dates rather than a calendar date.

What about green onions and leeks?

Green onions are ready when the tops reach about six inches, according to Iowa State. They can be pulled over a long period. Leeks can be picked small or left to size up, and many are tolerant of cold, so they can stay in the garden into late fall in many regions.

Harvest them with a fork to loosen soil, and trim roots and tops as you prefer.

What mistakes should you avoid?

Pulling in wet weather, skipping curing, trimming necks while still green, and storing damaged bulbs with sound ones are common mistakes. Sort carefully and use damaged bulbs first.

Keep a note of the date tops fell over, the weather at harvest and how well bulbs kept. That record will improve your timing each year.

For example, if tops fall over in a rainy week, resist the urge to bend them down yourself to speed things up. Natural fall-over is the better signal, and forcing it can leave you with thick necks and poor keeping.

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

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