Last Updated on: January 23, 2026

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Growing Onions from Onions: A Simple Guide to Regrowing Onions at Home

Growing onions from onions is one of the simplest and most satisfying ways to produce fresh crops at home. Instead of starting from seed or sets, you use an existing onion — often one that has already started sprouting — and regrow it into new plants. This method is ideal for beginners, budget-conscious gardeners, schools, and anyone who wants quick, visible results with minimal effort.

This guide explains exactly how regrowing onions works, when it’s worth doing, how to do it step by step, what results to expect, and the common mistakes that stop people getting good harvests.

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⭐ Recommended Tools & Supplies for Regrowing Onions

Growing onions from onions is low-tech, but the right basics make the process easier and more reliable.

• Sharp Kitchen Knife
Used to cut onions cleanly without crushing the growing point. A clean cut reduces the risk of rot.
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• Small Pots or Containers with Drainage
Ideal for starting onions indoors or on windowsills before planting outside.
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• Multi-Purpose or Vegetable Compost
Provides enough nutrients for early growth without being too rich.
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• Watering Can with Fine Rose
Allows gentle watering without washing compost away from the onion base.
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Can You Really Grow Onions from Onions?

Yes — but it’s important to understand what you’ll get.

When you regrow an onion:

• You usually produce spring onions (green onions)
• Or multiple smaller bulb onions, not one large replacement bulb

This method works because onions naturally try to reproduce by splitting into multiple growing points when conditions allow.

It’s best treated as:

• A fast, fun growing method
• A way to reduce food waste
• A reliable source of onion greens

If your goal is large, single bulbs for storage, onion sets or seed are better. But for quick harvests, regrowing works extremely well.

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Best Onions to Use for Regrowing

Not all onions perform the same way.

Best choices:

• Brown, white, or red onions from shops
• Onions with visible shoots or green tips
• Firm onions with no mould or soft patches

Avoid:

• Onions that are mushy or rotting
• Onions with strong mould smells
• Very small onions with no visible growing point

Sprouting onions already have active growth hormones — they regrow fastest.

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When Is the Best Time to Regrow Onions?

Onions can be regrown almost year-round, but results are best during brighter months.

Ideal times:

• Indoors: Any time of year
• Outdoors (UK): March to September
• Windowsill growing: Autumn and winter works well

They don’t need heat — just light and moisture.

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Method 1: Growing Onions from Onion Bases (Easiest Method)

This is the most common and reliable method.

Step 1: Cut the Onion

Cut off the bottom 2–3 cm of the onion, keeping the root plate intact.

Step 2: Let It Dry

Leave the cut base out for 12–24 hours so the cut surface dries slightly. This reduces rot.

Step 3: Plant the Base

Place the base root-side down in compost, just deep enough to cover the roots. The top should remain visible.

Step 4: Water Lightly

Water gently and place in a bright position.

Step 5: Watch It Grow

Green shoots appear within 3–7 days.

You can harvest greens repeatedly without killing the plant.

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Method 2: Regrowing Whole Sprouting Onions

This method produces multiple onion plants.

Step 1: Separate Shoots

If the onion has several shoots, gently peel it apart into sections. Each section can grow into a plant.

Step 2: Plant Individually

Plant each section with the roots down and the shoot just above the surface.

Step 3: Space Properly

Allow 10–15 cm between plants if growing outdoors.

This method can produce clusters of smaller bulbs later in the season.

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Growing Onions in Water (Short-Term Only)

Onions can regrow in water, but this is best for greens only.

How to Do It:

• Place the onion base in a shallow dish
• Roots touch water; onion stays above waterline
• Change water every 1–2 days

Limitations:

• No bulb formation
• Risk of smell and rot
• Short lifespan

For long-term growth, compost or soil is far better.

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Light Requirements

Light is crucial.

• Windowsill: South-facing is ideal
• Outdoors: Full sun to light shade
• Minimum: 6 hours of light per day

Poor light leads to weak, floppy growth.

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Watering Tips

Overwatering is the biggest cause of failure.

Correct watering:

• Keep compost lightly moist
• Never let plants sit in water
• Allow top compost to dry slightly between watering

Onions hate soggy roots.

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Feeding Regrown Onions

Onions regrown from kitchen scraps don’t need much feeding.

• No feed needed for greens
• Light liquid feed if growing longer-term
• Avoid high nitrogen — it encourages leaf growth over bulbs

Most nutrients come from the original onion.

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Can Regrown Onions Form New Bulbs?

Yes — but expect:

• Several small bulbs
• Clusters rather than singles
• Variable sizes

Bulbs form only if:

• Grown outdoors
• Given enough space
• Allowed a full growing season

Many gardeners regrow onions mainly for greens, not bulbs.

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Harvesting Regrown Onions

For Green Onions

• Start cutting when shoots reach 15–20 cm
• Cut outer leaves first
• Leave inner growth to continue

For Bulbs

• Harvest when leaves yellow and collapse
• Lift gently and dry before use
• Use fresh — storage life is short

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How Long Do Regrown Onions Last?

• Greens: Several weeks to months
• Bulbs: One season only
• Plants weaken over time

For continuous harvests, start new onion bases every few weeks.

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Common Mistakes to Avoid

❌ Burying onions too deeply
❌ Growing in low light
❌ Overwatering
❌ Expecting supermarket-sized bulbs
❌ Leaving bases in water too long

Understanding expectations is key to success.

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Is Regrowing Onions Worth It?

Yes — especially if you want:

• Free food from scraps
• Quick results
• A beginner-friendly project
• Fresh onion greens year-round

It’s not a replacement for traditional onion growing, but it’s a brilliant addition.

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Growing Onions from Onions vs Sets or Seeds

Regrowing from onions:

• Fast
• Free
• Best for greens

Onion sets:

• Reliable bulbs
• Better storage
• Seasonal planting

Seeds:

• Most control over varieties
• Longest growing time

Each method has its place.

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Final Thoughts

Growing onions from onions is one of the easiest ways to turn kitchen waste into fresh food. With minimal equipment, little space, and almost no cost, you can enjoy a steady supply of onion greens — and sometimes small bulbs — straight from your windowsill or garden.

If you’re new to growing vegetables or just want something simple that works, regrowing onions at home is the perfect place to start.

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