Grow Onion Greens from Scraps: Simple 7-Day Method

Yes, you can successfully grow new onion greens from an onion bottom in just 7-10 days using water or soil propagation. While you won't get a full-sized bulb, you'll harvest fresh green onion tops for cooking within weeks. The root end (1-2 inches) with intact roots is essential for regrowth.

Why Growing Onions from Scraps Makes Kitchen Gardening Simple

Transforming onion scraps into fresh greens is one of the easiest kitchen gardening projects you can start today. Unlike growing onions from seeds which takes 100-175 days, regrowing from scraps delivers usable greens in weeks with minimal effort. This zero-waste technique works because onions store energy in their bulb layers, allowing the root end to regenerate when given proper conditions.

Your Onion Regrowth Starter Kit: What You'll Need

Before beginning, gather these simple supplies:

• Onion bottoms (1-2 inch root sections with roots intact)
• Shallow container or jar
• Water or potting soil
• Sunny windowsill (6+ hours of light)
• Scissors for harvesting

Method	Time to First Greens	Harvest Potential	Best For
Water Propagation	5-7 days	Limited harvests (2-3 cuttings)	Quick kitchen supply
Soil Propagation	7-10 days	Multiple harvests (4-6 weeks)	Sustained production

Step-by-Step: Growing Onion Greens in 4 Simple Phases

Phase 1: Preparing Your Onion Base (Day 0)

Cut 1-2 inches from the root end of any onion (yellow, red, or white varieties work). Ensure the root plate remains intact with visible root nubs. Remove any loose outer layers but preserve the inner concentric rings. This preparation method follows recommendations from the University of Minnesota Extension's home gardening program which confirms that preserving the meristematic tissue in the basal plate is crucial for successful regeneration (extension.umn.edu/vegetables/growing-onions).

Phase 2: Choosing Your Growing Medium

Water Method: Place the onion base in a small container with the root end submerged 1/4 inch in water. Change water every 2-3 days to prevent bacterial growth. This method works well for quick kitchen supply but produces less robust growth.

Soil Method: Plant the onion base 1 inch deep in potting mix with the flat root end down. Water thoroughly and maintain consistent moisture. Soil propagation yields stronger, more sustainable growth as confirmed by Cornell University's gardening resources which note that soil provides essential nutrients for continued production (gardening.cce.cornell.edu).

Phase 3: Monitoring Growth (Days 3-14)

Within 3-5 days, you'll notice white roots extending into the water or soil. Green shoots will emerge from the center within 7-10 days. Position your container in bright, indirect light - onions require 6+ hours of daily light for optimal growth. During this critical development phase, maintain consistent moisture without waterlogging. The USDA National Institute of Food and Agriculture notes that Allium species like onions respond best to consistent moisture levels during initial regrowth stages.

Phase 4: Harvesting and Maintenance

When greens reach 6-8 inches tall (typically 2-3 weeks), harvest by cutting 1-2 inches above the bulb using clean scissors. This allows continued growth for multiple harvests. Never remove more than 1/3 of the green growth at once to maintain plant health. For soil-grown onions, apply a balanced liquid fertilizer every 2-3 weeks to sustain production.

Realistic Expectations: What You Will (and Won't) Grow

It's important to understand the limitations of this method. While you'll successfully grow fresh green onion tops, you won't develop a full-sized bulb. The energy stored in the original onion base supports leaf growth but isn't sufficient for bulb formation. This aligns with research from the Royal Horticultural Society which explains that complete bulb regeneration requires specific temperature fluctuations and longer growing periods not achievable through simple regrowth methods.

Troubleshooting Common Onion Regrowth Issues

• Yellowing tops: Usually indicates overwatering or poor drainage. Reduce water frequency.
• No growth after 10 days: The root plate may be damaged. Start with a fresh onion base.
• Mold on water surface: Change water more frequently and ensure only roots (not bulb) contact water.
• Thin, weak growth: Increase light exposure - onions need bright conditions for sturdy growth.

Maximizing Your Onion Regrowth Success

For continuous harvests, maintain 3-4 onion bases at different growth stages. When one plant's production slows (typically after 4-6 weeks), replace it with a new base. During summer months, you can transplant soil-grown onions to an outdoor garden for extended production. The University of California Master Gardener Program confirms that transplanted regrown onions often produce stronger growth when moved to garden conditions with proper spacing.

Can you grow a full onion bulb from an onion bottom?

No, regrowing from an onion bottom typically produces green onion tops but not a full bulb. The original bulb's stored energy supports leaf growth but isn't sufficient for complete bulb formation, which requires specific temperature cycles and longer growing periods.

How long does it take to grow onions from scraps?

You'll see green shoots emerging in 5-10 days, with harvestable greens ready in 2-3 weeks. Water propagation shows faster initial growth (5-7 days), while soil propagation takes slightly longer (7-10 days) but yields more sustainable production.

Which part of the onion is needed for regrowing?

You need the root end (1-2 inches) with the basal plate intact and visible root nubs. The concentric rings above the root plate provide the stored energy for regrowth. Discard the top portion of the onion as it won't regenerate.

Can you regrow onions from supermarket onions?

Yes, most supermarket onions work well for regrowth. Yellow, red, and white varieties all regenerate successfully. Avoid onions treated with sprout inhibitors (often labeled as 'long storage' varieties), as these may not grow properly.

How many times can you regrow the same onion base?

Most onion bases produce 2-4 harvests over 4-6 weeks before energy reserves deplete. Soil-grown onions typically yield more harvests than water-propagated ones. For continuous supply, maintain multiple bases at different growth stages.