How to Harvest and Store Onions

By John Rawling Gardening 0 Comments

Introduction

Onions are one of the most versatile vegetables in the kitchen, adding flavor and depth to countless dishes. Growing and harvesting onions in your own garden can be incredibly rewarding. Not only are they relatively easy to grow, but with proper care, you can also enjoy a bountiful harvest that will last for months if stored correctly.

In this guide, I’ll walk you through everything you need to know about how to harvest onions, care for them during the growing season, and store them properly for long-term use. Whether you’re a seasoned gardener or just starting, this information will help ensure a successful onion crop.

When to Plant Onions

Onions thrive in cool weather, making the timing of planting crucial to their success. In most regions, onions should be planted in early spring or late fall, depending on the variety you choose.

For spring planting, start seeds indoors about 8-10 weeks before the last expected frost date. Transplant the seedlings outdoors once the soil is workable and temperatures are consistently above 50°F. For fall planting, aim to plant onion sets about four to six weeks before the first hard frost.

The variety of onion you choose will also determine the planting schedule. Short-day onions are best planted in fall in warmer climates, while long-day onions do well in northern regions when planted in early spring.

Types of Onions

Before we dive into how to harvest onions, it’s important to understand the different types of onions you can grow. The type of onion you choose affects not only when and how you plant but also the flavor and storage longevity of the onions.

Yellow Onions: These are the most common type and have a slightly sweet, mild flavor. They store well for long periods.
Red Onions: Known for their beautiful color and mild, crisp taste, red onions are often used raw in salads. They don’t store as long as yellow onions but can still last a few months.
White Onions: With a sharper, more pungent flavor, white onions are perfect for Mexican dishes and salsas. Their storage life is shorter than that of yellow onions.
Sweet Onions: Varieties like Vidalia or Walla Walla are known for their sweetness. However, their high water content makes them less suitable for long-term storage.

Knowing your onion type will help you understand when to plant, how to harvest onions, and the best methods for storing them.

How to Grow Onions from Seed

Growing onions from seed is a cost-effective way to produce large quantities of onions. While sets (small onion bulbs) and transplants are available, starting from seed can give you more control over the variety and timing of your crop. Here’s how to do it:

Start Indoors: Begin by sowing onion seeds indoors 8-10 weeks before the last frost date. Use a seed-starting mix and plant the seeds about 1/4 inch deep.
Provide Light: Onion seeds need plenty of light to grow strong. If you don’t have access to natural sunlight, consider using grow lights for 12-16 hours per day. You can even read more about which plants like natural sunlight
Thin the Seedlings: Once the seedlings have grown a few inches tall, thin them out so each plant is spaced about 2-3 inches apart.
Transplant: When the seedlings are about 6 inches tall, transplant them into the garden. Space them 4-6 inches apart in rows that are about 12-18 inches apart.

How to Grow Onions in Pots

For gardeners with limited space, growing onions in pots is a great alternative. Follow these simple steps to grow onions in containers:

Choose the Right Pot: Onions need space to develop strong roots, so select a container that’s at least 10 inches deep and wide enough to allow proper spacing.
Use Well-Draining Soil: Onions prefer loose, well-draining soil. A mix of potting soil with compost will provide the necessary nutrients.
Plant and Water: Plant the onion sets or transplants about 2-3 inches apart and water them thoroughly. Onions need consistent moisture, so ensure the soil stays evenly damp but not waterlogged.
Sunlight is Key: Place the pots in a location that gets at least 6 hours of direct sunlight per day.

Pruning and Caring for Onions

Onions are fairly low-maintenance, but they do require some care to ensure a healthy harvest. Here are a few key tips for taking care of your onions:

Watering: Onions need regular watering, especially during dry periods. Water deeply about once a week or more often if the soil dries out quickly.
Fertilizing: Onions are heavy feeders and benefit from regular fertilizing. Use a balanced fertilizer every few weeks to encourage strong growth.
Weeding: Onions don’t compete well with weeds, so keep the garden bed weed-free to allow your onions to thrive.
Pruning: If you notice any dead or yellowing leaves, remove them promptly to allow the plant to focus its energy on producing bulbs.

Harvesting Onions: When and How

Now, the moment you’ve been waiting for—how to harvest onions! Knowing when to harvest onions is crucial to getting the best flavor and longest storage life. The timing depends on the variety and the growing conditions, but most onions are ready to harvest about 100-120 days after planting.

Here are the key signs that it’s time to harvest onions:

Falling Over: When the tops of your onion plants start to yellow and fall over, it’s a sign that the onions are nearing maturity.
Bulb Size: The bulbs should be full-sized and firm. If you can see the top of the onion above the soil, it should be about 3-4 inches in diameter.
Time of Day: It’s best to harvest onions in the morning on a dry, sunny day. This will help prevent moisture from affecting the onions during the curing process.
How to Harvest: Gently pull the onions from the soil by hand, being careful not to damage the bulbs. If the soil is compacted, use a garden fork to loosen the soil before pulling the onions out.

Curing Onions for Long-Term Storage

Once you’ve harvested your onions, the next step is curing. Curing is essential for extending the shelf life of your onions by allowing them to dry out and harden.

Lay Them Out: After you harvest onions, spread them out in a single layer in a warm, dry, well-ventilated area. Avoid direct sunlight, as it can cause the onions to sunburn.
Let Them Cure: Allow the onions to cure for about 2-3 weeks. You’ll know they’re fully cured when the necks are tight, and the outer skins are dry and papery.
Trim the Tops: Once the onions are cured, trim the tops, leaving about an inch of stem. Remove any dirt or loose skins but be careful not to damage the outer layers.
Storing the Onions: After curing, store the onions in a cool, dry, and well-ventilated space, such as a cellar or garage. Hang them in mesh bags or spread them out in a single layer on racks. Properly cured and stored onions can last for several months.

Common Pests and Plant Diseases

While onions are generally hardy plants, they can still fall victim to pests and diseases. Here are a few to watch out for:

Onion Maggots: These small larvae feed on the roots of onion plants and can cause stunted growth. Using row covers and crop rotation can help prevent infestations.
Thrips: Tiny insects that feed on the leaves, causing them to turn silver or brown. Insecticidal soap can help control thrips.
Fungal Diseases: Diseases like onion downy mildew and white rot can affect your plants. Prevent fungal diseases by ensuring proper air circulation, avoiding overhead watering, and rotating your crops each year.

Propagating Onions

If you want to grow onions from an existing plant, you can propagate them using cuttings from the onion’s root end or from sets. Here’s how:

Cut the Root End: After using an onion in the kitchen, save the root end. Place it in a shallow dish of water, ensuring the root side is down.
Transplant to Soil: After a few days, once you see new roots forming, transplant the cutting into soil. With proper care, it will grow into a full onion plant.

Tips for Storing Onions

After curing, properly storing your onions is essential to ensure they last for months. Here are some key tips:

Ideal Temperature: Store onions in a cool, dry place, ideally between 35°F and 50°F. Avoid storing them in the refrigerator as the moisture can cause them to spoil.
Air Circulation: Onions need good air circulation to prevent rot. Avoid storing them in plastic bags. Instead, use mesh bags or hang them in bunches.
Avoid Moisture: Keep your onions dry to prevent them from sprouting or rotting. Always check for any signs of rot and remove affected onions immediately.
Storage Duration: Yellow onions can last up to six months in proper storage conditions, while red and white onions typically last about 3-4 months.

Wrapping Up

Learning how to harvest onions and store them properly is essential for every gardener. From the right time to plant to understanding how to care for and prune your onions, every step contributes to a successful harvest. Don’t forget to cure your onions before storing them to extend their shelf life and enjoy fresh onions for months.

With a little attention to detail, you can grow onions that not only enhance your cooking but also make your garden thrive. Now that you know how to harvest onions and store them, it’s time to get your hands dirty and experience the joy of homegrown onions. Happy gardening!