Can You Grow Onions Indoors? A Practical, Step-by-Step Guide for Beginners

Introduction: Can you grow onions indoors and why it matters

Yes, you can grow onions indoors, and it is easier than most people think. You can regrow scallions on a sunny windowsill in water within a week, or grow full bulbs in containers with potting mix and a grow light. Expect a clear difference though, green onions are fast and low effort, bulb onions need more depth, light, and 90 to 120 days to mature.

This guide shows which onion varieties work best inside, how big your pots should be, soil recipes, lighting and watering schedules, plus harvesting and storage tips. You will get step by step planting instructions, troubleshooting for pests and rot, and realistic yield expectations for both scallions and bulb onions.

Which onion types work best indoors

Yes, you can grow onions indoors, but some types are much easier than others. For quick wins pick green onions, for actual bulbs use onion sets, and for long term interest try small or perennial varieties.

Green onions, also called scallions, are the simplest. Regrow kitchen scraps in water or plant roots in a shallow pot, and you will harvest new tops in 7 to 14 days. Try White Lisbon or Evergreen Bunching for reliable, mild flavor.

If you want bulbs, start with onion sets rather than seed, they form bulbs faster and are more forgiving. Use a pot 6 to 8 inches deep, strong light or a grow light, and choose small or short-day types. Egyptian walking onion and small red varieties like Red Baron work well in containers.

If you are unsure, begin with scallions and graduate to sets once you understand light and space needs.

What you need to get started, fast

Short answer to can you grow onions indoors? Yes, if you have the right gear. Start with containers, 4 to 6 inches deep for scallions, 8 to 12 inches deep and 8 to 10 inches wide for bulb onions, pots with drainage holes and a saucer. Use a loose, well-drained potting mix, mixed with 10 to 20 percent perlite and a handful of compost, or a quality mix like Miracle-Gro or FoxFarm. Light matters, aim for 6 to 8 hours from a south-facing window or 12 to 14 hours under a full spectrum LED or a 2-tube T5 fixture on a timer. Keep a small watering can, hand trowel, moisture meter or finger test, and snips for harvest. A balanced vegetable fertilizer or fish emulsion finishes the list.

Planting options explained: seeds, sets, transplants and regrowing scraps

If you wonder, can you grow onions indoors, the short answer is yes, but the method matters. Seeds give the most variety, start indoors 8 to 10 weeks before transplant, and need 12 to 20 weeks to form bulbs; expect more time and patience. Onion sets are small dormant bulbs you plant 1 inch deep, 4 inches apart, in a 6 to 8 inch deep pot, they are the fastest route to harvestable bulbs. Transplants are nursery seedlings, ready to go and reliable for consistent size. Regrowing scraps works great for green onions, place the root end in shallow water until roots form, then pot, you will get fresh tops in 1 to 2 weeks but not large bulbs. For beginners, use sets for bulbs and regrow scraps for quick greens.

Step-by-step planting guide you can follow today

If you wondered can you grow onions indoors, follow these simple steps and start today.

1. Pick the right container. For green onions use a 6 to 8 inch deep pot. For bulb onions choose a 10 to 12 inch deep container, at least 8 inches across, with drainage holes.

2. Fill with a loose potting mix, two parts potting soil to one part compost. Mix in a handful of slow-release granular fertilizer for steady nitrogen.

3. Planting depth and spacing. Seeds go 1/4 inch deep, thin to 1 to 2 inches apart for scallions or 4 to 6 inches apart for bulbs. Sets and transplants sit about 1 inch deep, eyes up.

4. Press soil gently, firming around each plant so roots make contact, but do not compact.

5. First watering matters. Water until you see drainage, this settles the soil. Keep soil evenly moist; let the top inch dry slightly between waterings.

6. Place pots in bright light, 10 to 14 hours daily, and you will be harvesting in weeks for scallions, months for bulbs.

Light, temperature and watering rules that actually work

If you’re asking can you grow onions indoors? yes, but light is the number one factor. For bulbing varieties give 14 to 16 hours of strong light daily; for scallions and green onions 12 to 14 hours is fine. Use a timer, no guessing.

Aim for daytime temperatures between 60 and 75°F (15 and 24°C), with nights cooler around 50 to 60°F (10 and 15°C). These ranges encourage bulb development without stressing plants.

Water when the top inch of soil feels dry, typically once or twice a week in pots 4 to 6 inches deep; smaller pots need more frequent checks. Keep soil evenly moist, not waterlogged.

Use a full spectrum LED labeled for vegetables, hang 6 to 12 inches above the foliage, and raise the light as shoots approach 4 inches from the source.

Ongoing care and feeding for bigger bulbs and tastier greens

If you’re asking can you grow onions indoors, feed them regularly and they reward you. Use a balanced liquid fertilizer, for example 10-10-10, every 10 to 14 days while tops are growing. When bulbs begin to swell, about 6 to 8 weeks in, cut nitrogen back by half or switch to a lower nitrogen formula to push energy into bulb development. Top up settled potting mix by about 1 inch every 3 to 4 weeks to keep roots covered and moisture steady. For perpetual greens, harvest outer leaves, then feed with fish emulsion every 10 to 14 days and keep soil evenly moist.

Common indoor pest and disease issues and simple fixes

Yes you can grow onions indoors, but expect a few pests and diseases. Aphids cluster on green tops, sucking sap and spreading viruses. Knock them off with a strong spray of water, wipe leaves, or use insecticidal soap twice a week until gone.

Mold and powdery mildew show as white or gray fuzz, usually from poor airflow or high humidity. Improve ventilation, trim crowded leaves, and remove infected tissue.

Root and bulb rot come from overwatering or poor drainage. Switch to a gritty potting mix with perlite, use pots with drainage holes, and water at the base only when the top inch of soil is dry. Clean tools between plants to prevent spread.

How and when to harvest, plus storage and reuse tips

For green onions, harvest when tops reach 6 to 8 inches, snip the outer stalks at soil level, and leave the inner shoots to keep growing. You can also pull a few whole plants for immediate use, but never harvest the entire bed at once if you want continuous supply. For onion bulbs, wait until tops yellow and fall over, and most storage varieties mature in about 90 to 120 days. Lift bulbs when the neck feels dry, brush off excess soil, then cure in a warm, well-ventilated spot for 7 to 14 days.

For storage, keep cured bulbs in a cool, dry place with good airflow, they can last several months. To regrow scraps, place 1 inch of root-end pieces in water or replant them in potting mix, new shoots appear in about 3 to 10 days. This answers can you grow onions indoors with practical steps to harvest, store, and reuse for continuous supply.

Troubleshooting common problems fast

If you still ask can you grow onions indoors, here are quick diagnostics and fixes you can apply right now.

• Yellow leaves: often overwatering or nutrient deficiency. Check soil moisture, cut back watering, feed with a balanced fertilizer once, then every 3 weeks. Move to brighter light if pale leaves persist.

• Small bulbs: crowded plants or too much nitrogen. Thin to 4 inches between plants, transplant to deeper containers 8 to 10 inches, stop heavy nitrogen feeding four weeks before harvest.

• Bolting: stress from heat or temperature swings. Keep nighttime temps cooler, keep soil evenly moist, harvest tops early if bulbs abort.

• Watery or rotten stems: poor drainage or fungal rot. Repot in fast-draining mix, trim rotten tissue, improve airflow, avoid overhead watering.

Conclusion and quick action checklist

Yes, you can grow onions indoors, and it is easier than most people think. Quick wins: start with onion sets or regrow green onions from store-bought bulbs, use a sunny south window or a 12 to 14 hour LED grow light, and pick a pot deep enough for the variety you want.

Action checklist to get started this week

1. Choose variety, sets, or scallions.
2. Pot: at least 6 inches deep for scallions, 8 to 12 inches for bulb onions.
3. Soil: loose, well-draining potting mix with added compost.
4. Light: 12 to 14 hours daily, supplement with a grow light if needed.
5. Water: keep soil moist, not soggy; feed every 2 to 3 weeks.
6. Harvest: scallions in 3 to 4 weeks, bulbs in 90 to 120 days.

Plant one tray now, learn by doing, then scale up.