How to Grow Onions from Seed

Onions are one of the first plants you can start indoors to kick off the year. Or consider planting onion seeds in fall! Today, we’ll walk you through the process of how to grow onions, some decisions you need to make, & highlight pitfalls to avoid.

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Welcome to the world of growing onions – where the simple act of sowing an onion seed can lead to you harvesting onions from your very own garden! In this comprehensive guide, we will explore how to grow onions from seeds (and a little bit about onion sets too).

Learn about the onion types available to you, from short-day onions that thrive in milder climates to long-day onions that flourish in regions with extended daylight hours. We’ll also review seasonal considerations – comparing the benefits of planting onions in fall versus spring.

So whether you’re a seasoned gardener seeking to expand your onion-growing expertise or a beginner eager to cultivate your own kitchen staples, let’s delve into how to grow onions from seed.

Onion Types

Onions come in various types, each with its own unique flavor profile, culinary uses, and growing characteristics. Let’s explore the main different types of onions:

1. Yellow Onions:

• Flavor Profile: Yellow onions are the most versatile and widely used onions. They have a strong, pungent flavor and a slightly sweet undertone. When cooked, they develop a rich and savory taste.
• Culinary Uses: Yellow onions are great for sautéing, caramelizing, and adding depth to soups, stews, and sauces. They are a staple in many savory dishes.
• Our Favorites: Walla Walla, Patterson, Talon

2. Red Onions:

• Flavor Profile: In terms of pungency, red onions are the sharpest – much spicier than the slightly sweet yellow onions & known for their vibrant purple-red color.
• Culinary Uses: Red onions are often used raw in salads, sandwiches, and salsas. They add color and bite to dishes. Also great for pickling.
• Our Favorites: Redwing, Barolo

3. White Onions:

• Flavor Profile: White onions are the mildest of these three main bulbing varieties. For that reason, white onions are one of the best candidates for raw applications.
• Culinary Uses: White onions are commonly used in Mexican and Southwestern cuisines. They work well in fresh salsas, guacamole, and dishes where a subtle onion flavor is desired.
• Our Favorites: Sierra Blanca

4. Bunching Onions (Green Onions or Scallions):

• Flavor Profile: Bunching onions have a mild, oniony flavor. Both the green tops and the white bulbs are edible.
• Culinary Uses: Bunching onions are often used as a garnish for salads, soups, and Asian dishes. They can be used raw or lightly cooked to add a fresh and crisp onion flavor.
• Our Favorites: Ramrod

5. Shallots:

• Flavor Profile: Shallots have a mild and sweet flavor with a hint of garlic. They are known for their small, elongated bulbs.
• Culinary Uses: Shallots are popular in French cuisine and are used in dressings, sauces, and dishes where a subtle onion and garlic flavor is desired. They can be sautéed or used raw.
• Our Favorites: Creme Brulee

6. Chives:

• Flavor Profile: Chives have a mild onion flavor with a hint of garlic. They are known for their thin, hollow green stalks.
• Culinary Uses: Chives are often used as a garnish for salads, soups, and baked potatoes. They are a popular herb for adding a mild onion taste without the bulk of traditional onions. The bees also love chive flowers.
• Our Favorites: Staro

7. Leek:

• Flavor Profile: Leeks have a mild, sweet, and slightly oniony flavor with a hint of garlic. The flavor is subtler than traditional onions, making leeks a versatile and delicate addition to various dishes.
• Culinary Uses: Leeks are often used in both raw and cooked forms, offering a unique flavor to a range of dishes. When raw, they add a mild onion flavor to salads and dressings. Cooked leeks provide a sweet and savory element to soups, stews, quiches, and casseroles.
• Our Favorites: American Flag, Lancelot

Long-Day Onions vs Short-Day Onions vs Intermediate Onions

Now when it comes to three main bulbing onions types (yellow, red, & white), you’ll need to select your variety based on your location. Short-day, long-day, & intermediate onions refer to different types of onions that have specific day-length requirements for bulb formation.

Short-Day Onions

Short-day onions are varieties that form bulbs when exposed to shorter daylight periods. Typically, they require 10-12 hours of daylight to trigger bulb development. These onions are well-suited for growing in regions with milder winters and closer to the equator.

Popular short-day varieties include Vidalia and Texas Sweet. Gardeners in the southern United States often favor short-day onions due to their ability to produce bulbs in their climate with shorter day lengths during the growing season.

Long-Day Onions

Long-day onions, on the other hand, form bulbs when exposed to longer daylight periods. They typically need 14-16 hours of daylight to initiate bulb growth. Long-day onions are better suited for regions with longer daylight hours, typically found at higher latitudes or in northern climates.

Varieties like Walla Walla and Ailsa Craig are popular choices for gardeners in the northern United States and Canada. These onions thrive in areas where summer days are extended, allowing for optimal bulb development.

Intermediate Onions

Intermediate onions, also known as day-neutral onions, fall between short-day and long-day varieties in terms of their day-length requirements for bulb formation. These onions have a more flexible response to day length, allowing them to form bulbs in a wide range of day lengths.

Intermediate onions are a versatile choice for gardeners who may not fit precisely into short or long-day growing regions. They offer adaptability and can be grown successfully in various climates, making them a popular option for those seeking a reliable onion crop without strict day-length constraints.

It is important to buy the correct onion variety for your locale. Most seed packets and stores will state specifically which zone each onion seed is best suited.

Is it better to grow onions from seed?

Growing onions from seeds and sets are two common methods, each with its own advantages and considerations. Let’s explore the differences between growing onions from seeds and sets:

Growing Onions from Seeds

Advantages:

1. Varietal Choices: Growing onions from seeds offers a wide range of onion varieties to choose from. You have the flexibility to select the specific size, color, and flavor that best suits your preferences and growing conditions.
2. Cost-Effective: Seeds are generally more cost-effective than sets. A packet of onion seeds contains numerous seeds, providing plenty of opportunities to grow a substantial number of onions.
3. Better Storage Potential: Onion seeds have a longer shelf life compared to sets. This allows you to store seeds for multiple growing seasons if kept in proper conditions.

Considerations:

1. Longer Growing Time: Onions grown from seeds typically take a longer time to mature compared to those grown from sets. Starting onions from seeds requires more patience as you wait for the seeds to germinate and develop into seedlings.
2. Indoor Starting: To get a head start on the growing season, onion seeds are often started indoors several weeks before the last frost date. This involves providing adequate light and maintaining optimal temperature conditions.

Growing Onions from Sets

Advantages:

1. Faster Maturity: Onions grown from sets tend to mature more quickly than those grown from seeds. Sets are essentially small, dormant onion bulbs that have been planted the previous year and are ready to grow into full-sized onions.
2. Convenient Planting: Planting onion sets is a convenient and time-saving method. You can skip the initial stages of seed germination and seedling care, making it an attractive option for gardeners looking for a simpler process.

Considerations:

1. Limited Varietal Choices: Onion sets are often available in fewer varieties compared to seeds. If you have specific preferences for onion types, you might find a more limited selection when using sets.
2. Susceptibility to Bolting: Onions grown from sets may have a higher risk of bolting (premature flowering and seed production), especially if exposed to fluctuating temperatures. Bolting can impact the quality of the onion bulbs.

Ultimatley, the choice between growing onions from seeds or sets depends on factors like your preferred varieties, available time, and desire for convenience. Personally we favor growing onions from seed because of the varieties available & longer storage, but both methods can result in successful onion crops when approached with the right knowledge and care.

Stay tuned for our future article with more info on how to plant onion sets.

Planting Onion Seeds in Fall vs Planting Onions in Spring

Planting onions in fall versus spring involves considering the climate, the onion variety, and the desired harvest time. Let’s explore the differences between planting onions in these two seasons:

Planting Onion Seeds in Fall

Advantages:

1. Early Growth: Planting onions in the fall allows them to establish roots and start growing before winter dormancy. This early start can lead to larger and earlier harvests in the following year.
2. Reduced Risk of Bolting: Onions planted in the fall are less likely to bolt (premature flowering and seed production) because they experience the vernalization process during winter, which helps prevent bolting.
3. Minimal Competition: Fall-planted onions often face less competition from weeds compared to spring-planted onions. This can contribute to healthier and more robust plants.

Considerations:

1. Winter Protection: In regions with harsh winters, fall-planted onions may require protection, such as a layer of mulch, to shield them from extreme cold temperatures.
2. Limited Variety Options: Not all onion varieties are suitable for fall planting. Some may not withstand winter conditions, so it’s essential to choose varieties that are specifically recommended for fall planting.

Planting Onions in Spring

Advantages:

1. Simplicity: Spring planting is often more straightforward, especially in areas with severe winter weather. It eliminates the need for winter protection measures and allows for direct planting as the soil warms.
2. Wide Variety Selection: Spring planting provides a broader selection of onion varieties, as more onions are adapted to spring planting conditions. Gardeners have more options in terms of size, flavor, and color.

Considerations:

1. Later Harvest: Onions planted in the spring typically have a later harvest compared to fall-planted onions. They may take longer to mature as they go through the entire growing season.
2. Increased Bolting Risk: Spring-planted onions may be more prone to bolting, especially if they experience stress factors like sudden temperature fluctuations or extended cold periods.
3. Weed Competition: Spring-planted onions may face more competition from weeds, as they start growing alongside other vegetation in the garden.

In the end, the decision to plant onions in fall or spring depends on your local climate, the specific onion varieties you prefer, and your gardening goals. We prefer planting onion seeds in fall, but both approaches can yield successful onion crops when aligned with the right conditions and care.

How to Grow Onions from Seed

In this section, we will take you through our step-by-step guide for successfully planting onion seeds in spring. Learn more on how to plant onion seeds in fall here.

Certainly! Growing onions from seed can be a rewarding experience, and it allows you to enjoy the satisfaction of nurturing your own crop from the very beginning. Here’s a step-by-step guide on how to grow onions from seeds:

1. Choose the Right Onion Seeds: Start by selecting the onion variety that suits your taste and growing conditions. Onions come in various sizes, colors, and flavors. Common varieties include red, yellow, and white onions. Ensure that the seeds you choose are fresh and from a reputable source.

2. Seed Starting Containers: Use seed trays or small containers to start your onion seeds indoors. Fill the containers with a good quality seed starting mix. This provides a loose and well-draining medium for the seeds to germinate. Learn more about starting seeds in recycled milk containers here.

3. Sow the Seeds: Plant the onion seeds about ¼ inch deep in the soil. Space the seeds evenly in rows or broadcast them over the surface. Lightly press the soil to ensure good seed-to-soil contact.

4. Provide Adequate Light: Onions require plenty of sunlight for healthy growth. Place the seed trays in a location where they can receive at least 12-16 hours of light per day. If natural sunlight is insufficient, consider using grow lights. Learn more about our grow light system here.

5. Maintain Optimal Temperature: Onions prefer a temperature range of 60-75°F (15-24°C) for germination. Keep the seed trays in a warm environment until the seeds sprout. This process usually takes 7-10 days.

6. Watering: Keep the soil consistently moist but not waterlogged. Onions are susceptible to rot if the soil is too wet. Water the seedlings gently to avoid disturbing the delicate roots.

7. Transplanting: Once the onion seedlings have reached a height of 4-6 inches and have developed a strong root system, they are ready to be transplanted outdoors. Don’t bother thinning the seedlings prioor to transplanting. Onions are incredibly hardy & the roots will tease apart easily. Choose a location with well-draining soil and plenty of sunlight.

8. Soil Preparation: Prepare the soil by adding compost or well-rotted manure to improve fertility. Onions thrive in slightly acidic to neutral soil with a pH range of 6.0-7.5.

9. Planting Outdoors: Dig shallow furrows in the prepared soil and transplant the onion seedlings, spacing them according to the recommendations for the chosen variety. Water the transplants thoroughly after planting. Learn more about what to plant next to your onions here.

10. Mulching and Watering: Apply a layer of mulch around the onions to retain moisture, suppress weeds, and regulate soil temperature. Water consistently, providing about 1 inch of water per week.

What if I Can’t Start Seeds Indoors?

That’s okay! You can still sow them directly into your garden. In this case, it’s best to wait until spring or they won’t have the required temperature needed to germinate – which is about 65 degrees F. Alternatively, you may want to consider planting onion sets to get the most growth with a later headstart.

Checking Our Onions Videos Below to Learn More!

As we wrap things up, our hope is that you feel inspired to grow onions from seed this year. Remember, onions are very forgiving and quite hardy. They’re perfect for beginners and a welcome addition to your garden.

So whether you choose to start from seeds or sets, know that the key lies in patience, care, and a little bit of onion knowledge. May your gardening endeavors be filled with abundance and freshly harvested onions.

Happy Growing!

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