Growing Onions From Seed: Tips and Tricks

Onions are a versatile vegetable that can be used in a variety of dishes. They also add flavor and depth to any recipe, making them an essential ingredient in most kitchens. While onions can be grown from sets or transplants, growing them from seed is a cost-effective and rewarding option.

Choosing the Right Onion Seeds

Before you start growing onions from seed, it’s essential to choose the right variety. There are three main types of onions: short-day, intermediate-day, and long-day. Short-day onions need fewer hours of daylight to form bulbs and are suited for southern regions. Intermediate-day onions require slightly more daylight and grow well in the Midwest. Long-day onions need up to 14-16 hours of sunlight and thrive in northern regions.

When selecting onion seeds, look for those labeled as “long-day” if you live in the northern parts of the United States. If you live in the south, opt for “short-day” seeds. Of course, it doesn’t hurt to experiment with different varieties to see which ones grow best in your area.

Starting Onion Seeds Indoors

If you want to get a head start on your onion crop, you can start seeds indoors four to six weeks before the last expected frost. To do this, fill small containers with potting soil and plant one seed in each container. Keep the soil moist but not wet and place the containers in a warm, sunny spot.

Once the seedlings have emerged, keep them under grow lights for 12 to 16 hours per day. You can also supplement natural light with artificial light if needed. Once the weather warms up outside, harden off the seedlings by gradually exposing them to outdoor conditions for one to two weeks before transplanting them into the garden.

Planting Onion Seeds Outdoors

If you prefer to start your onion seeds outdoors, wait until the soil temperature reaches at least 50°F (10°C) before planting. To prepare the soil, work in compost or well-rotted manure to a depth of 6-8 inches. Rake the soil smooth and create furrows about ½ inch deep.

Plant the onion seeds about ½ inch apart in the furrows and cover with soil. Water the seeds gently and keep the soil moist but not waterlogged. When the seedlings emerge, thin them out to 4-6 inches apart so they have room to grow.

Caring for Your Onion Seedlings

Onion seedlings need consistent moisture but don’t like to be overwatered. Aim to provide about one inch of water per week, either through rainfall or irrigation. Avoid overhead watering, which can promote disease. Instead, water the soil around the plants so the water goes directly to their roots.

To keep weeds under control, mulch around the base of the onion plants with straw or another organic material. This will help retain moisture and reduce weed growth.

As the onion plants grow, you may notice that they start to develop flower stalks. These are called scapes and should be removed to encourage bulb formation. Simply snip off the scapes when they appear.

Harvesting Your Onion Crop

Onions are ready to harvest when their tops start to turn yellow and fall over. Gently dig up the onions and allow them to dry in a warm, well-ventilated area for several days. Once the outer layers of skin are papery and the necks are completely dry, trim off the tops and roots and store the onions in a cool, dry place.

Starting onion seeds indoors

Growing onions from seed is a fun and rewarding experience that results in delicious, homegrown onions. Whether you start your seeds indoors or plant them directly in the garden, be sure to choose the right variety for your region and provide them with consistent care.

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