Onion Seeds

Can You Grow Onions from Seeds?

Yes, most onion varieties can be grown from seed. In fact, it’s a great option if you want to start your seedlings indoors so you can transplant them as soon as outdoor conditions are right. Onion seeds are also more cost-effective than starting with sets or buying seedlings.

The best way to grow onions from seeds is to start them indoors about 8–10 weeks before the final frost. Choose a variety suitable for your climate and consider the day length where you live as well. Choose long day onion varieties for colder climates and short day varieties for warmer climates.

Is It Better to Grow Onions From a Seed or Bulb?

It depends. If you want to plant your onions before the last frost or be able to harvest them sooner, it may be better to use onion sets (small, partially formed bulbs) than onion seeds. Starting with onion sets may also yield a stronger plant and a larger yield than seeds.

Onion sets can be sown as soon as the soil is workable in spring—you don’t have to wait until the danger of frost has passed. This option makes the most sense for larger varieties like white onions and yellow onions than for quick-growing varieties like green onions.

When Is the Best Time to Plant Onion Seeds?

Onion seeds can be planted in either the spring or fall, depending on your climate and the variety. It also depends on whether you want to harvest the bulbs for immediate use or store them for later. Here are some tips to keep in mind:

• Spring planting - Sow the seeds directly in the ground about 6–8 weeks before the final frost date in your area (or as soon as the soil is workable).
• Fall planting - Direct-sow the seeds about 6–8 weeks before the first frost in fall if you plan to overwinter the onions.
• Transplanting seedlings - Start onion seeds indoors at least 8 weeks before you want to transplant them (the earlier you start, the stronger your bulbs will be).

If starting with seeds, plant them in loose, well-draining soil about ¼ inch deep and 1 inch apart. Once the seedlings sprout, thin the seedlings to about 4 inches apart.

How Long Do Onions Take to Grow From Seed?

Onions generally take anywhere from 90 to 120 days to grow from seed and be ready for harvest. Some varieties can be harvested sooner. Green Onions, for example, can be harvested in as little as 60 days and leeks generally take about 75-80 days to grow to maturity.

Starting with high-quality seeds and starting them indoors is the best way to ensure a healthy harvest. Soaking the seeds for 12–24 hours before sowing them can help them germinate more quickly, especially if you’re sowing them directly outdoors or in suboptimal conditions.

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