Knowing when to harvest onions is the final, crucial step to getting the biggest, most flavorful bulbs from your garden. For optimal bulb size, timing is everything—pull them too early and they’re small, too late and they might not store well.
This guide will walk you through the clear signs that your onions are ready, the simple steps to harvest them correctly, and how to cure them for long-term storage. Let’s get your onions out of the ground at the perfect moment.
When To Harvest Onions
Onions tell you they’re ready through clear signals in their tops. Unlike many vegetables, you don’t judge readiness by the bulb itself, since it’s hidden underground. Instead, you watch the leaves.
The Top Signs Your Onions Are Ready
Look for these three natural changes in your onion plants:
* The Neck Softens: The area where the leaves meet the bulb (the neck) will start to feel soft and lose its rigidity. This is a key internal signal that the onion is shifting from growth mode to dormancy.
* Tops Begin to Fall Over: This is the most obvious sign. About half to three-quarters of the tops will naturally flop over at the neck. They’ll look like they’re laying down. It’s the plant’s way of saying it’s done growing.
* Leaves Change Color: The green leaves will start to turn yellow and then brown, beginning at the tips and moving down. This is normal and indicates the plant is diverting its final energy into bulbing up.
It’s important not to bend the tops over yourself. Let the plant initiate this process naturally for the best results.
Different Timelines for Different Onions
Not all onions follow the exact same schedule. The type you planted affects your harvest window.
* Bulbing Onions (from sets or transplants): These are the classic storage onions. They typically take 90-120 days to mature. Always check your seed packet for the “days to maturity” for your specific variety.
* Scallions (Green Onions): You can harvest these at any stage when the green tops are tall and succulent, usually just 60-70 days after planting. Size is a personal preference here.
* Onions Grown from Seed: These often take the longest, sometimes up to 130 days. They require more patience but can produce excellent, large bulbs.
Weather plays a huge role, too. A hot, dry season can accelerate maturity, while a cool, wet one can delay it. That’s why watching the plant’s signs is more reliable than the calendar alone.
What to Do If Your Onions Flower
Sometimes an onion will send up a tall, central flower stalk. This is called “bolting.” It’s usually triggered by a period of cold weather after growth has started.
When an onion bolts, it stops putting energy into the bulb and focuses on making seeds. The bulb will often become tough and won’t store well.
* If you see a flower stalk: Snap it off immediately. Harvest that onion first and plan to use it within a few weeks, as it won’t cure for long storage. The bulb might still be usable, but it won’t reach its optimal size.
The Step-by-Step Harvest Process
Once most of your tops have fallen over, it’s time to act. Follow these steps for a successful harvest.
1. Pick the Right Day
Choose a dry, sunny morning if possible. Harvesting after a period of dry weather is ideal. Wet soil can make the process messy and wet onions are much more prone to rot during curing.
2. Loosen the Soil
Gently insert a garden fork or trowel into the soil about 4-6 inches away from the bulb. Lift slightly to loosen the roots and soil. This prevents you from yanking on the stem and damaging the bulb.
3. Lift the Bulbs
Carefully grasp the onion near the base and pull it up. If the soil is still tight, use your tool to loosen it a bit more. Avoid bruising or puncturing the bulbs, as this creates an entry point for decay.
4. Handle with Care
Place the harvested onions gently in a crate or basket. Don’t drop them or pile them too high, as the weight can cause damage. They’re more fragile than they look at this stage!
Pre-Harvest Tips for Bigger Bulbs
A few practices during the growing season directly influence your final bulb size:
* Consistent Watering: Onions need steady moisture, especially during bulb formation (when the tops stop producing new leaves and start falling over). About 1 inch of water per week is a good rule.
* Stop Watering at the Right Time: Once about half the tops have fallen over, stop watering altogether. This allows the outer skin to tighten up and the neck to begin drying, which is essential for curing.
* Feed Them Well: Onions are moderate feeders. A balanced fertilizer at planting and a side-dressing of a nitrogen-rich feed when they begin to bulb can support strong growth. But avoid high nitrogen late in the season, as it can promote top growth at the expense of the bulb.
Curing and Storing Your Harvest
Curing is not optional if you want your onions to last. This process dries the outer layers and the neck, sealing the bulb for storage.
How to Cure Onions Properly
1. Find a Good Spot: You need a warm, dry, well-ventilated place out of direct sun. A covered porch, garage, shed, or a well-ventilated barn is perfect. Direct sun can actually scorch the bulbs.
2. Lay Them Out: Spread the onions in a single layer. You can use screens, racks, or even just lay them on a dry floor. Good air circulation on all sides is key.
3. Let Them Dry: Leave them to cure for about two to three weeks. The outer skins will become papery, the roots will shrivel, and the necks will dry out completely. You should not be able to feel any moisture at the neck.
Preparing for Storage
After curing, you need to prep your onions for their long rest.
* Trim the Roots: Use clean scissors or pruners to snip off the dried roots, leaving about half an inch.
* Trim the Tops: You have two options. You can braid the tops if they are still flexible, or you can trim them down to about 1-2 inches above the bulb. Never cut the top flush with the bulb, as this opens it up to rot.
* Sort Your Onions: Gently feel each onion. Any with thick, soft necks, bruises, or soft spots should be set aside for immediate use. Only store the firm, perfectly cured bulbs.
Best Practices for Long-Term Storage
Store your cured onions in a cool, dark, and dry place. Ideal conditions are around 35-40°F with 65-70% humidity, but a cool basement or cellar works well for many gardeners.
* Use the Right Container: Mesh bags, old pantyhose, or woven baskets are excellent because they allow air to circulate. Avoid plastic bags, which trap moisture.
* Check Periodically: Every few weeks, give your stored onions a quick check. Remove any that have started to soften or sprout immediately to prevent spoilage from spreading.
* Know Your Varieties: Some onion varieties simply store longer than others. Generally, pungent yellow and red storage onions last the longest, while sweet white onions have a shorter storage life and should be eaten first.
Frequently Asked Questions (FAQ)
Can you leave onions in the ground too long?
Yes, you can. If left in wet soil after maturity, the bulbs can start to rot or re-sprout. In very dry soil, the protective papery skin can split, making them vulnerable. It’s best to harvest within 1-2 weeks after tops have fallen.
What if it rains before I harvest?
If a rainstorm is forecast and your onions are ready, go ahead and harvest them. It’s better to get them out of soggy soil. You’ll just need to be extra diligent during curing to ensure they dry thoroughly, perhaps with a fan for added airflow.
How do I know when my onions are fully cured?
The neck will be completely dry and tight, like a paper straw. The outer skin will be uniformly papery and rustle when touched. You should not be able to squeeze any moisture from the top of the bulb.
Why are my onion bulbs so small?
Small bulbs can result from several factors: planting the wrong variety for your day-length zone, overcrowding, inconsistent watering, poor soil fertility, or harvesting too early before the bulbs have fully expanded.
Can I eat onions right after harvest?
Absolutely! Fresh, uncured onions are delicious and often juicier. Just remember that they haven’t developed the protective dry layers, so they won’t last more than a week or two on the counter. Use these first and save the cured ones for later.
Getting the timing right for your onion harvest is a simple skill that pays off with a bounty of beautiful, large bulbs. By watching for the natural signs, handling your crop gently, and taking the time to cure them properly, you’ll enjoy homegrown onions for months to come. There’s nothing quite like reaching into your own storage in the middle of winter for an onion you grew yourself.