How Long Do Onion Seeds Take to Germinate

Have you ever wondered how long it takes for onion seeds to germinate? Most gardeners wish seeds would grow quickly, but onion seeds take their time. They are slow to sprout, and the process can be unpredictable. So, how many days until onion seeds grow?

Onion seeds need 7 to 10 days to start. But, this time frame can change based on where they are planted. Colder soil can make them take up to two weeks longer to grow. However, if it’s warm, they might come up in just four days.

Why do onion seeds take longer to grow? Onions are a special type of plant that makes seeds in its second year. This makes the seeds take longer to start growing. Also, onion seeds need some time asleep before they wake up and grow.

If you find onion seeds slow to grow, it’s normal. But, there are tricks to speed things up. One way is to sprout the seeds before you plant them. This can make more seeds grow, especially if you are starting them indoors. A popular way to do this is by putting the seeds on a wet paper towel in a bag until they start to grow.

Whether you know a lot about gardening or just started, knowing onion seed growth is key. In the coming sections, we will cover the best ways to plant and care for onion seeds. These tips will help you grow more onions and have a great harvest.

Sowing Onion Seeds

It's key to use fresh onion seeds for best results because old seeds don't sprout well. Plant the seeds somewhere sunny or in a greenhouse from February to April. While not required, a little warmth under the seeds can make them sprout in 7 to 10 days.

Timing is vital for a good onion harvest. Start your seeds 10-12 weeks before your area's last frost date. For certain results, especially if you want big bulbs, start 16 weeks ahead sometimes.

For a high germination rate, the seeds need the right care. Always pick fresh seeds. Get the timing right and adding a bit of extra warmth can speed things up.

Remember, different onion types take varying times to grow, about 75 to 110 days. This depends on daylight and climate where they're planted. Know the needs of your onion type to plant at the correct time.

Onions come as long-day, short-day, and day-neutral types, each preferring different climates. Picking the right type for where you live ensures best results.

If you want onions that keep well, choose varieties known for their long storage. This ensures you can keep enjoying your homegrown onions longer.

Growing from seed means you get to pick the exact variety you like. It offers more control and promotes self-reliance, great in uncertain times.

When planting, make sure the seedlings have all they need. Gradually help them get used to the outdoor weather and protect them from cold. Always care for the growing onions properly.

Pick the right starting container and water properly to grow strong seedlings. Since onion seeds take a while to sprout, start them indoors during the winter. This way, they'll be ready to thrive when it's planting time.

Pre-sprouting onion seeds on damp paper can increase how many sprout. This step can lead to a better overall germination rate.

Onion seedlings need light, warmth, water, and attention to thrive. Ensure they get enough light, especially in winter, and keep them warm when needed. Good watering and sometimes a bit of fish emulsion for nutrition can help a lot.

onion seed germination timelinePin

In summary, sowing onion seeds successfully means paying attention to details and providing the right conditions. By using fresh seeds, choosing the correct time, and offering the necessary warmth and care, you can get a good crop of onions. Growing from seed has many pluses, including specific variety choices, increased productivity, and a step towards self-sufficiency. Stick to these tips, and you'll harvest plenty of homegrown onions.

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Planting Onion Seedlings Outside

When onion seedlings are 3" tall and have a third leaf, it's time to put them in the ground. This usually happens in May or June, based on where you live. For the best growth, do the following:

  1. Prepare the soil: Add rich fertilizer to the soil before planting. It gives the seedlings the nutrients they need to grow well.
  2. Plant vertically: Put the seedlings upright, with the tip of the bulb just a little under the soil. This helps the roots to grow and meets the onion's space requirements.
  3. Spacing: How you space seedlings depends on the onion type. If it's a smaller onion, plant them 2-4" (4-10cm) apart. For larger ones, use a 8-10" (20-25cm) gap between each. Leave 9" (22cm) between rows for air and growth space.

By planting onion seedlings this way, you give them a good start outside. They will have plenty of room and the soil they need to grow strong and make big onions.

onion seedling growth periodPin

Maturity Period
Long-Day Onions
90-110 days
Short-Day Onions
110 days (warmer zones in fall), 75 days (colder zones in early spring)
Day-Neutral Onions
110 days

Know that different onions take varying times to grow. Long-day onions need 90-110 days to mature. Short-day types need 110 days in fall's warmer zones, or 75 in early spring's colder areas. Day-neutral onions also mature in about 110 days. Knowing the onion's type helps you plan for harvest time.

Next section: Container Growing Onions

Container Growing Onions

If you want to grow onions in containers, set up the right conditions. Move the seedlings when they're about 3" (8cm) tall and have a third leaf. Pick containers that are at least 10" (25cm) deep. This ensures your onions have room to grow.

Each onion needs about 3 inches of space. So, plant them 2-10" (4-25cm) apart. Keep the rows 9" (22cm) apart. This gives your onions enough air and space to thrive.

Avoid using compost high in nitrogen. It can make your onions grow more leaves than bulbs. Instead, pick a compost that's well-balanced. This will help your onions grow strong and healthy.

Container Growing Onions: Recommended Spacing and Depth

Container Depth
Spacing Between Onion Seedlings
Spacing Between Rows
At least 10" (25cm)
2-10" (4-25cm) apart
9" (22cm)

speed up onion seed germinationPin

Follow these tips for a great harvest of tasty onions. You can do it right from your own garden. Happy growing!

Looking after your Onion Plants

Taking proper care of your onion plants is key to their health. With the right steps, you can make sure they grow well. This will also boost the success of your onion garden.

Weed Control

Weeds are not friends with onion plants. Keeping the area around them clean is vital. This stops weeds from stealing food and water from the onion seedlings. So, they can really take off.


Trimming the tops of your onion seedlings to 5 inches helps. It stops them from getting too heavy and falling over. This makes them stronger and grow better.


Watering your onion seedlings right is important, especially when it's dry. The soil should be moist but not too wet. Always check the soil to make sure you're not watering too little or too much.

Ripening Process

When the onion leaves turn yellow, try bending the tops over. This helps the bulbs grow better and bigger. It's a way to make your onions healthier.

Following these tips can really make a difference in your onion garden. Always keep an eye on them. Tweak your care as needed to guarantee a great harvest.

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Harvesting Onions

Harvesting onions at the right time is key for their quality. It also helps prevent them from rotting. Onions are best harvested between July and October. Lift them before the ground gets too wet because dampness can cause them to spoil.

When it's time to harvest, be gentle. Dig the onions out without hurting the bulbs. Be sure to keep the greens on when you pull them up.

After you've harvested, leave the onions in the sun for a bit. This dries them and makes them good for keeping.

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Not all onions grow ripe at the same time. This means some might be ready before others. It's smart to pick them as you need them. This way, you can enjoy fresh onions for longer and avoid any wastage.

Harvesting Tips
Harvest onions from July to October
Lift onions before the soil becomes excessively wet
Allow onions to dry in the sun for a few days
Harvest onions as needed, rather than all at once

Storing Onions

Keeping your harvested onions fresh for a long time is key. Just a few simple steps can help you do this. These steps will ensure your onions taste great even after months.

Start by picking out the best onions for storage. Any that aren't perfect should be used up first. This will stop them from going bad.

A jute Veg Sack is an excellent choice for onion storage. It lets air move through, keeping the onions at their best. You can also store onions in a cool, dark place at home.

Remember, not all onions last the same amount of time. Some can stay good for six months. But, others may not keep as well and have a shorter life.

Follow these tips to make your homegrown onions last a long time. This way, you can enjoy their flavor and health benefits for more months.

Best Practices for Onion Seed Germination

Growing healthy onion plants starts with successful seed germination. Follow these tips for the best results and a great harvest.

2. Start with fresh seeds. New seeds have better chances to grow. If you must use older seeds, plant more to make sure you get enough.

3. Warmth is key. Onion seeds like a cosy spot to sprout. Placing them in a sunny window or a greenhouse will help.

4. Give seeds enough light. Seedlings need lots of light to thrive. Increase daily exposure from 14 hours, up to 18 hours, to help them grow faster.

5. Keep soil moist but not soaked. Onions' shallow roots need consistent water. Don't let the soil dry out, but avoid making it swampy.

6. Be mindful of soil space. Plant spacing helps avoid using up soil nutrients too fast. Space onion seedlings well, especially if planting in the same area.

7. Pay attention to day lengths. Different onions need specific sunlight amounts to grow well. Start planting based on this as it affects their development.

8. With these tips, you can help onions grow quickly. Tailor your planting and care to suit your local climate for the best outcome.

Common Challenges in Onion Seed Germination

Onion seed germination, though simple, faces some hurdles. A few factors can affect how well the seeds sprout and grow. Knowing these obstacles is key to a good harvest. Here’s what you should watch out for:

1. Temperature

Temperature is vital for onion seed germination. Start your seeds in January or February. However, how long it takes for seeds to sprout changes with the temperature. Usually, they sprout in 7 to 14 days. Warmer weather speeds this up. But cooler soil can slow it down, even to 2 weeks. Make sure to keep the temperature just right for the best results.

2. Seed Quality

The quality and freshness of onion seeds matter. Older or damaged seeds may not sprout well. It’s best to use new seeds. This increases your chances of having healthy onion plants.

3. Seed Husk Shedding

Sometimes, onion seedlings have trouble shedding their seed husks. They might look stuck. It’s not a good idea to help by cutting the husk. Most times, they will work it out on their own as they grow.

4. Soil Conditions

The soil's quality is also crucial. Onions do best in soil that drains well but holds moisture. The soil shouldn't be too tight. It should let air through easily. A pH between 6.0 and 7.8 is just right for onions.

5. Weeds and Competition

Weeds are a big problem for onion seeds. They fight for the water and nutrients the seeds need. Keep the area free from weeds. Or use strategies to control them.

6. Premature Bolting

If onion plants flower too early, it’s called premature bolting. This can happen for many reasons, like too much temperature change. Some onion types are more at risk. Harvest these plants quickly. They won’t store for long.

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7. Pests and Diseases

Different pests and diseases can trouble onion plants. Thrips, onion fly maggots, and white rot are common issues. Make sure to fight these off. This keeps your plants healthy.

Impact on Germination
Extended germination period at cooler temperatures
Seed Quality
Lower germination rates with older or damaged seeds
Seed Husk Shedding
Inconsequential natural process
Soil Conditions
Poor soil drainage and aeration can hinder germination
Weeds and Competition
Compete for essential resources, hindering growth
Premature Bolting
Bulb formation disrupted, reduced storage potential
Pests and Diseases
Damaged seedlings, compromised health

To get a great onion harvest, tackle these challenges. Keep the right temperature, choose good seeds, look after the soil, and control weeds and pests. These steps will lead to strong, healthy onion plants.

Benefits of Growing Onions from Seeds

Growing onions from seeds has many perks over starting from sets. Bigger bulbs can grow as sets tend to stop and flower sooner. This info comes from experts at Texas A&M and Michigan State. Seeds let gardeners pick from a wide variety, unlike sets which offer only a few choices.

One big advantage of seeds is they're more economical, especially for onion lovers. More seeds can be planted, leading to a bigger onion crop. This approach is easier on the wallet for those tending their own gardens.

Seeds also bring a broader choice of onions to gardeners. With many varieties, gardeners can find the perfect one for taste, color, and size. It lets everyone customize their onion crop for cooking.

On the whole, starting onions from seeds saves money and provides more flexibility. Gardeners looking to mix up their onion selection will find seeds the best option. It opens the door to a richer onion-growing experience.

Tips for Successful Onion Seed Starting

Starting onions from seeds is a great way to get tasty harvests. To boost your chances of success, here are some handy tips:

  1. Use fresh seeds: Always start with seeds that are new. Fresh seeds germinate better, giving you healthier plants.
  2. Provide the necessary conditions for germination: To get onion seeds to sprout, they need warmth and moisture. You can create a mini greenhouse by covering your pots with a lid or plastic bag. Also, putting them on a heat mat or in a warm space helps.
  3. Ensure ample light: After they sprout, onion seedlings need lots of light to grow right. Make sure they're in a bright place or use special lights for plants. This helps them grow strong without getting too tall and weak.
  4. Practice regular weed control: Onions don’t like weeds because they have short roots. Keep your growing area clean. Weeding gently helps keep water around the onions and keeps them healthy.

By following these suggestions, you can kick-start your onion growing journey with success. This way, you'll have robust little plants to move to your garden.


Growing onions from seeds needs the right setup and ongoing care. Seeds take about six weeks to start, but you'll see them sprout in 7-10 days. Yet, not all seeds will grow, which makes success tricky.

Buying your onion seedlings is often the best choice. If you grow them from seeds, make sure they aren't too close together. Having too many plants in one pot can limit their growth. Aim for spacing them 4-6 inches apart.

Knowing your onion type's light needs is crucial for good growth. Short-day onions do well with 10-12 hours of light, perfect for the south. Long-day onions prefer 12-14 hours and are fine in most places. Those that love the most light need 14-16 hours and do best up north.

Onions like soil that's a bit acidic to neutral, with a pH of 6.0 to 6.8. It must drain well to avoid root problems. Before planting, make sure to loosen the soil down 8 to 12 inches deep. This improves root growth and helps with drainage.

For the best results, buy your seeds from a good source. This way, you give your onions the best chance to grow well and produce plenty.

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