How to Grow an Onion From an Onion Bulb: Can a Sprouted Onion Really Grow Again?
If you’ve ever found onions that are sprouting in your kitchen, you might ask, can you grow onions from a sprouted onion or even can you grow onions from an onion you already have. It seems simple, but what happens next is often misunderstood.
This guide explains how to grow onions from onions that have sprouted, what results to expect, and when it’s better to use seed or sets instead.
Why Onions Start Sprouting
When stored onions begin forming green shoots, they are no longer dormant. These onions that are sprouting are trying to grow again using energy stored in the bulb.
At this stage, the onion sprout pulls nutrients from the bulb, which changes how the plant develops if you replant it.
Can You Grow Onions From an Onion?
The short answer is yes. You can try growing onions from an onion, but it will not behave like a freshly planted crop.
If you’re wondering how do onions grow from an onion, the sprouted bulb has already completed its first life cycle. When replanted, it usually divides into multiple shoots instead of forming one large bulb.
This is why growing onions from onions often produces smaller results than expected.
What Happens When You Plant a Sprouted Onion
If you try how to grow an onion from a sprouted onion, the outcome is different from planting seed or sets.
Growth Pattern
- The bulb may split into several smaller bulbs
- It may produce flower stalks
- Growth focuses on leaves rather than large bulbs
This explains why growing onions from bulbs that have already sprouted is less reliable for bulbing onions.
How to Plant a Sprouted Onion
If you want to try how to plant a sprouted onion or how to plant onions that have sprouted, the process is simple, but a few details make a big difference in success.
Planting Steps
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Choose the right location
- Select a spot that receives full sun for most of the day. Onions need plenty of light to grow well. If sunlight is limited, growth may be slow or weak.
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Prepare the soil
- Use a loose, well-drained garden bed. Onions do not grow well in compact or waterlogged soil. Mix in compost or other organic matter to improve drainage and provide nutrients.
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Check the sprouted onion
- Look at the onion closely. If it has one strong sprout, you can plant it whole. If there are multiple green shoots, gently peel back the outer layers of the bulb to separate the sections. Each section can grow into its own plant.
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Plant at the correct depth
- Place the onion or separated sections root-side down, about 1 to 2 inches deep. The top of the sprout should sit just above the soil surface. Planting too deep can slow growth.
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Space the plants properly
- Leave a few inches between each plant so they have room to grow. Crowded onions compete for nutrients and may stay small.
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Water consistently
- After planting, water thoroughly. Keep the soil evenly moist, especially during the first few weeks. Avoid letting the soil dry out completely, but do not overwater.
This process works for how to grow onions from an onion or how to grow onions from onions that have sprouted, but results can vary depending on conditions and the type of onion.
What to Expect After Planting
After planting, the sprout will continue growing upward, and new roots will develop below the soil. In many cases, the plant focuses on producing green tops rather than forming a large bulb.
If multiple shoots were separated, each one may develop into a smaller onion or produce green onion tops that can be harvested.
This makes sprouted onions especially useful for growing fresh green onions, even if they do not produce full-size bulbs.
Better Ways to Grow Onions
While how to grow onions from onions is possible, better results come from starting with seeds or sets.
Growing Onions From Seed
Growing onions from seed gives you more control over size and quality. Many gardeners prefer onions that are grown from seed because they develop stronger root systems.
For step-by-step instructions, see this guide on how to grow onions successfully.
Choosing the Right Onion Type
Different types of onions perform best in different regions:
- Long day onions for northern climates
- Short day onions for warmer areas
Choosing the right onion variety improves bulb formation and yield.
Recommended Onion Seeds
If your goal is consistent harvests, starting from seed is the most reliable option.
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Walla Walla Onion Seeds (Organic)
- A sweet onion suited for fresh use
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Cortland Onion Seeds (Organic)
- A strong storage onion for long term storage
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Evergreen Bunching Onion Seeds (Organic)
- Ideal for growing spring onions and green tops
Explore more options in this collection of organic onion seeds.
How Long Does It Take for Onions to Grow?
Many gardeners ask, how long does it take for onions to grow.
- From seed: about 90 to 120 days
- From sets: about 60 to 90 days
Timing depends on weather, soil conditions, and whether you start onions indoors using grow lights or plant directly outside.
Common Mistakes When Growing Onions
Whether you are growing onions from seedlings, seed, or bulbs, a few mistakes can reduce success.
- Planting too deeply or too shallow
- Poor soil without enough organic matter
- Not enough sunlight
- Overcrowding plants
For troubleshooting, see this guide on solving common onion growing challenges.
Conclusion
So, how to grow a sprouted onion? Yes, you can plant a sprouted onion, but it is not the best way to grow large bulbs. Sprouted onions tend to divide into smaller bulbs or produce more leafy growth instead.
If your goal is a strong harvest, it’s better to use seeds or onion sets. This approach leads to more predictable results when harvesting onions, especially if you want full-sized bulbs. Still, learning how to grow a sprouted onion can be useful if you want to grow green tops or simply experiment with the process.
Understanding how onions grow will help you choose the right method and improve your results over time, making harvesting onions more successful and consistent.
