Propagation
Your kitchen scraps can grow into a fresh harvest of red onions in just 6-8 weeks. ✨ I’ve regrown onions from store-bought bulbs so many times, I’ve lost count—and each batch tastes sweeter than the last.
The secret? Planting the right way, keeping them consistently moist, and giving them enough sunlight to thrive.
You’ll need just a few things: a bulb with roots (or one you can coax into sprouting), a shallow pot or garden bed, well-draining soil, and a sunny spot.
No fancy tools or expensive supplies—just patience and a little attention. Even if you’ve never grown onions before, this method is foolproof for beginners.
By the time you’re snipping fresh green onions for salads or cooking, you’ll have plump red bulbs ready to harvest. The flavor deepens as they mature, and you’ll never buy onions again. Plus, the process is oddly satisfying—like magic, but with dirt and water.
Works in containers or garden beds, and you can start indoors or outdoors, depending on your climate. Let’s get those onions growing!
📚 In This Guide
- What you need
- Instructions
- Tips and common mistakes
- Wrapping up and next steps
What you need
- ● Red onion bulb: 1-2 mature, firm bulbs (store-bought or homegrown). Choose ones with short, stubby roots already forming at the base.
- ● Shallow container: A small bowl, saucer, or 6-inch-wide dish with drainage holes (or a plate if you’re using the "paper towel method").
- ● Water: Room-temperature tap water (changed daily).
- ○ Scissors or knife: For trimming the bulb (optional, if roots aren’t already present).
- ○ Well-draining soil (optional for transplanting): A small pot (4-6 inches wide) with potting mix or a sunny windowsill spot if keeping indoors.
- ● Hydroponic setup: A clear jar or mesh grow bag for root observation (fun for kids!).
- ● Plant food: A diluted liquid fertilizer (like seaweed extract) to speed growth if transplanting.
- ● Grow lights: If your space lacks sunlight (LED or fluorescent bulbs work).
- ● Notebook: To track growth stages and harvest dates!
Step-by-step instructions for growing red onions from bulbs
Turn last week's scraps into a fresh harvest in just a few weeks with this simple method.
🪴 Step 1: Prepare the Onion Base for Regrowth
Save the white root end of your red onion bulb—about 1 inch of the base. Trim off any dried roots or browned sections with a clean knife. Leave the roots intact if they're still firm and white. This base holds the potential for new growth, so don't cut too much away.
Place the trimmed base in a shallow bowl of room-temperature water, making sure the roots are fully submerged. Change the water every 2-3 days to prevent bacterial growth. You'll notice tiny green shoots emerging from the top within 3-5 days—this is your first sign of success.
☀️ Step 2: Transfer to Soil for Stronger Growth
Once you see 1-2 inch tall green shoots and a few new roots growing from the base, it's time to plant. Fill a small pot—at least 6 inches deep—with well-draining potting mix. Make a hole in the center just deep enough to cover the onion base up to the bottom of the green shoots.
Gently place the onion base into the hole, covering it with soil but leaving the green shoots exposed. Water lightly until the soil feels evenly moist. Position the pot in a spot with bright, indirect light—a south-facing window works well. Avoid direct sunlight at first, which can scorch the tender new growth.
💧 Step 3: Maintain Moisture and Light for Harvest
Keep the soil consistently moist but not soggy—water when the top inch feels dry to the touch. Overwatering can cause the onion to rot, while underwatering slows growth. A small pot will dry out faster, so check daily during warm weather. You'll know you're doing it right when the green shoots grow steadily upward.
After 2-3 weeks, when the green shoots reach 6-8 inches tall, you can begin harvesting. Cut the greens just above the soil line with clean scissors, leaving the base intact. The onion will continue producing new growth for 4-6 weeks, giving you multiple harvests from a single bulb.
✂️ Step 4: Encourage Continued Growth (Optional)
If you want to maximize your harvest, leave the onion base in the pot after cutting the greens. Keep it in bright light and maintain consistent moisture. New shoots will emerge within 1-2 weeks, and you can continue harvesting every 2-3 weeks until the base becomes too small or the greens turn bitter.
When the onion base finally stops producing, compost it. You've gotten every last bit of life from this kitchen scrap! This method works best with red onions, which regrow more reliably than yellow or white varieties. Store-bought onions often yield better results than those grown from seed.
Tips & tricks for regrowing red onions from scraps
Turn kitchen scraps into a thriving green harvest with these simple but game-changing insights.
Selection Tip: Start with the freshest red onions you can find—those with firm, white root bases and minimal drying at the ends. I've noticed store-bought onions regrow better than homegrown ones, likely because they're often treated to last longer on shelves. Look for bulbs where the root end still feels plump and moist, not shriveled or papery.
Water Wisdom: When you first place your onion base in water, use room-temperature water to avoid shocking the roots. I've learned the hard way that cold water can slow down or even stop regrowth entirely. Change that water every 2-3 days as instructed, but don't skip this step—stagnant water breeds bacteria that can rot your onion before it even sprouts.
Light Strategy: That bright, indirect light recommendation in Step 2 is crucial. I've seen onions scorch under direct sunlight within hours, turning yellow and crispy. If you don't have a south-facing window, place your pot under grow lights for 12-14 hours daily. The key is gradual acclimation—move the pot closer to the light source over 3-4 days once the shoots appear.
Harvesting Hack: When your greens reach 6-8 inches, cut them just above the soil line with clean scissors. This might seem counterintuitive, but leaving that small base intact allows the onion to keep producing new growth for weeks. I've gotten four separate harvests from a single onion base by following this method—it's like getting free fresh herbs!
Pro Tips for Growing Red Onions From Bulbs
- Turn kitchen scraps into a thriving green harvest with these simple but game-changing insights.
- Selection Tip: Start with the freshest red onions you can find—those with firm, white root bases and minimal drying at the ends.
- Water Wisdom: When you first place your onion base in water, use room-temperature water to avoid shocking the roots.
Frequently asked questions
Got questions about regrowing red onions from scraps? We’ve got answers!
Here are the most common queries—plus quick fixes and pro tips—to help you grow lush, edible onions like a green thumb.
Can I regrow red onions from any store-bought bulb?
Yes! Most red onions sold in stores will regrow, but choose fresh, firm bulbs with roots still attached. Avoid sprouted or wilted onions—they won’t regrow well. The key is picking bulbs that look healthy and haven’t dried out.
How long does it take for regrown onions to be ready to harvest?
Regrown onions typically take 4–6 weeks to grow long enough for snipping (2–3 inches). For full bulbs, you’ll need 3–4 months in the ground. Patience pays off—harvest when the green tops are thick and the bulb is mature!
What if my regrown onion tops turn yellow or mushy?
Yellowing or mushy greens often mean overwatering or poor drainage. Let the soil dry slightly between waterings, and ensure your container has drainage holes. Too much moisture invites rot—keep it moist, not soggy!
Can I grow red onions indoors year-round?
Place your jar or container near a sunny window (6+ hours of light daily) or under a grow light. Just rotate the jar occasionally for even growth. Indoor regrowth is slower but works perfectly for fresh snips anytime.
What can I do with the leftover onion bulb after regrowing?
Don’t toss it! Once the greens are harvested, the bulb may sprout again if kept in water. For a second round, trim the greens, re-root the bulb, and repeat. If it’s too small, compost it—it’s nutrient-rich!
Why aren’t my regrown onions growing straight?
Onions lean toward light! If yours are bending, rotate the jar quarter-turns daily to encourage upright growth. A small weight (like a pebble) can also help anchor wobbly stems.
Still stumped? Drop your question in the comments—we’re happy to help you grow like a pro!
Wrapping up and next steps
Growing red onions from scraps is a rewarding way to save money, reduce waste, and enjoy fresh, homegrown produce—all in just a few weeks! With minimal effort and a little patience, you can turn kitchen leftovers into thriving plants.
Now that you’re equipped with the know-how, why not give it a try? Start with a single bulb, experiment with different conditions, and watch your green (or purple!) harvest grow. Happy regrowing! 🌱