How To Know When Red Onions Are Ready To Harvest

Knowing how to know when red onions are ready to harvest is the key to getting sweet, crisp bulbs that store well. If you pull them to early, they won’t have developed their full flavor or size. But if you wait to long, they might not store properly or could even start to rot in the ground. This guide will walk you through the simple signs that your onions are perfectly ripe and ready.

Growing red onions is rewarding, but the waiting can be tough. Unlike some vegetables that give obvious signals, onions are a bit more subtle. You need to watch for changes in both the tops and the necks of the plants. With a few easy checks, you’ll gain the confidence to harvest at just the right moment.

This is the main question every gardener faces. The answer lies in observing your plants closely, usually as summer begins to fade. Red onions, like all bulb onions, tell you they’re done growing through a natural process called “bulbing.” Here’s what to look for.

The Top Signs Your Red Onions Are Ripe

First, look at the green tops of your onions. These leaves are the plant’s energy factories. When the bulb has reached maturity, the plant begins to shift its energy.

Leaf Tipping and Yellowing: The very first sign is often a slight yellowing or browning at the very tips of the leaves. This is normal and signals the beginning of the end of the growth cycle.
Falling Over: The most reliable visual cue is when the green tops (the necks) become soft and can no longer support themselves. They will flop over at the neck, bending about halfway down the stalk. When about 50-80% of your onion tops have fallen over naturally, harvest time is near.

It’s crucial that this falling over happens naturally. Don’t bend them over yourself thinking it will help. This can damage the neck and invite disease.

The Neck Test: The Final Check

Even after the tops fall over, the bulb underground is still doing important work. It’s curing its neck—the area where the leaves meet the bulb—to seal it for storage. You need to check this before pulling.

Gently feel the neck of a few onions where the leaves bend over. In the days after the tops fall, this neck will start to soften and feel papery.
When the neck is fully soft and has no more green, firmness, it is effectively “cured on the vine.” This is the perfect time to harvest.
If the neck is still thick and green, the onion is still moving nutrients to the bulb. Give it another week.

Timing and Days to Maturity

While nature’s signs are best, your planting notes provide a good backup. Check the seed packet or plant tag for the “days to maturity.”

Most red onion varieties take between 90 and 110 days from planting sets or transplants to reach full maturity.
This is just a guideline. Weather, soil, and water can speed up or slow down growth. Always trust the plant’s visual signs over the calendar.

What About Flower Stalks?

If your onion sends up a tall, central flower stalk (called “bolting”), it’s diverting energy from the bulb. This is often triggered by a cold snap after growth has started.

Once an onion bolts, the bulb will not grow any larger and won’t store well.
You should harvest bolted onions immediately and plan to use them first, as there storage life is very short.

The Step-by-Step Harvest Process

When your onions show the right signs and have soft necks, follow these steps for a successful harvest.

Choose the Right Weather: Pick a dry, sunny day if possible. Harvesting in wet conditions can introduce excess moisture that leads to rot during curing.
Loosen the Soil: Gently insert a garden fork or trowel into the soil about 6 inches away from the bulb. Lift the soil to loosen it, rather than pulling on the tops directly, which can break the stalk off the bulb.
Lift the Bulbs: Carefully grasp the bulb and lift it from the loosened soil. Shake off any large clumps of dirt, but don’t wash them or bang them together aggressively.
Handle with Care: Any bruise or cut on the bulb becomes an entry point for rot. Treat them gently like eggs.

Curing Your Red Onions for Storage

Harvest is only half the job. Proper curing is what allows onions to last for months. Curing dries the outer layers and seals the neck completely.

Lay Them Out: Place your onions in a single layer on a breathable surface. A wire rack, a screen, or even on dry newspaper in a garage or covered porch works well.
Provide Ideal Conditions: They need warm, dry, airy conditions with good ventilation. Aim for 75-85°F (24-29°C) if you can. Avoid direct, harsh sunlight which can actually cook them.
Let Them Dry: Allow the onions to cure for about two to three weeks. The outer skins will become papery and crisp, the necks will dry shut, and the roots will shrivel.
The Final Test: The curing is complete when the neck is totally dry and tight, and the outer skin rustles when you touch it.

Storing Your Perfectly Harvested Onions

After curing, prep them for long-term storage. Brush off any remaining dry soil, trim the roots off with shears, and cut the dried tops down to about 1-2 inches, unless you plan to braid them.

Use mesh bags, old nylon stockings, or woven baskets—anything that allows for maximum air circulation.
Store in a cool, dark, dry place like a basement, cellar, or pantry. Ideal storage temperature is between 35-50°F (2-10°C).
Check your stored onions every few weeks and remove any that have gone soft, as one bad onion can spoil others nearby.

Common Problems and Solutions

Sometimes, things don’t go exactly as planned. Here’s what to do.

My Onion Tops Aren’t Falling Over

If it’s late in the season and tops are still standing tall, they might need a nudge. You can gently lift the bulbs with a fork to partially break some roots. This can stress the plant slightly and encourage it to start the maturing process. Reduce watering significantly as well.

I Have a Wet Forecast During Harvest Time

If heavy rain is coming and your onions are ready, harvest them anyway. It’s better to have 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 airflow in a covered area.

My Onions Are Very Small

Small bulbs often result from to much competition, not enough sun, or poor soil nutrition. For next year, ensure you thin seedlings properly, plant in full sun, and amend your soil with compost or a balanced fertilizer at planting time.

FAQ: Your Red Onion Harvest Questions

Can you eat red onions right after harvest?

Absolutely! Fresh, uncured red onions are often juicier and milder. You can eat them straight from the garden. Just remember, they haven’t developed the protective dry skin, so they won’t last long on the counter.

How long do cured red onions last?

Properly cured and stored red onions can last for several months, often up to 6 months or more in perfect conditions. Some varieties are bred specifically for longer storage.

What happens if you harvest onions too early?

Onions harvested to early will have thin, wet necks that are prone to rot. The bulbs won’t have reached their full size, and they will not store well at all. They’ll need to be used quickly.

What is the best time of day to harvest onions?

Aim for late morning on a dry day, after the dew has evaporated but before the afternoon heat is at its peak. This helps keep excess moisture to a minimum.

Why are my red onions not very red?

The intensity of the red color can vary with variety, soil conditions, and sunlight. Often, the color develops and deepens during the curing process, so don’t worry if they seem pale at first.

Learning how to know when red onions are ready to harvest takes a season or two of practice. The main thing is to be patient and let the plant show you it’s ready. By focusing on the falling tops and the soft, papery neck, you’ll harvest bulbs that are sweet, firm, and ready to flavor your meals for months to come. There’s nothing quite like the satisfaction of pulling a perfect, ruby-red onion from your own garden soil.