Growing Onions Indoors – Garden Tips 2024

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Onions are a staple vegetable found in every family’s kitchen. While most gardeners plant onions outside, growing onions indoors is easy and will ensure you always have a supply of onions close at hand.

So, how to grow onions indoors? Plant onion bulbs into a pot and bury them around 2 inches deep. Cover the onion bulbs with potting soil and water, so the soil is damp to the touch. Place the pot where it can get around 6 or 7 hours of sunlight per day. Check the soil daily and water enough to keep it moist at all times. 

Growing onions indoors is easy, and this article will show you how to grow onions from bulbs and seeds indoors. 

Can You Grow Onions Indoors?

Yes, it’s possible to grow onions indoors. An onion is a vegetable and the most commonly cultivated species of the genus Allium. Onions are also known as common onions and bulb onions. 

An onion is a cool-weather vegetable commonly grown in outside gardens. But experienced and novice gardeners can grow onions indoors all year round.  

To plant an onion indoors, you’ll need a deep container to allow the bulbs to form and grow. Indoor-grown onions also need well-draining soil and exposure to sunlight. 

Place the potting container in a sunny area with a lot of natural sunlight during the growing season. Artificial light might be necessary during the fall and winter months, so consider investing in fluorescent or incandescent light or a grow lamp. 

When growing onions indoors, choose a variety that produces small bulbs, as container-grown vegetables have limited room to grow. 

How to Grow Onions Indoors

There are several ways to grow onions indoors. Onions naturally resprout, so you can grow new onions from old onion bulbs or use onion seeds.

How to Grow Onions Indoors from Old Bulbs

Choose the type of onion you want to grow before you start gathering the rest of your supplies. Green onions, scallions, shallots, and yellow, red, and white onions are popular with indoor gardeners because they are easy to grow.

To grow onions at home, you’ll need a container with a draining hole that’s at least 6 inches deep. If you want to grow bigger onions, choose a deeper container that will give them more space to grow. 

Plastic, ceramic, or glass containers are all suitable for growing onions. It’s up to you to choose the material based on your preferences, budget, and style. 

Fill the container with a potting mix soil leaving about 1 inch of space between the top of the soil and the top of the container. Although not necessary, you can use a nitrogen-rich fertilizer to improve the size and quality of your onions. 

Using your fingers, make a 2 inches deep hole in the potting soil and place the onion bulb inside. Cover the bulb with soil, and water it until the soil is moist. Make sure that the soil is damp to the touch and not soaking wet. 

Place the potting container where it can get around 6 to 7 hours of sunlight daily. If it’s impossible to give your plant this much sunlight, use fluorescent or incandescent light or a grow lamp. 

Check the soil daily and water it to keep it moist at all times. In areas with mild climates, indoor-grown onions need at least 2 inches of water per week. Water your onion more if you live in a particularly hot and arid environment.

When onion sprouts are 3 inches high, harvest your onion or wait longer to allow the bulb to grow more. 

How to Grow Onions from Seeds

To plant onion seeds, you’ll need at least 6 inches deep partitioned container with drainage holes. Fill the partitions with a potting mix, leaving around 0.5 inches of space between the soil and the top of the container. 

Plant two or three onion seeds in each partition by lying them on top of the soil. Cover the seeds with a thin layer of soil and water until moist. 

Place the potted onion seeds where they can get at least 6 to 7 hours of sunlight per day. If you live in a location with less sunlight, use an artificial light source as a grow lamp or fluorescent and incandescent light as a supplement for natural sunlight. 

Check the soil daily by pushing the top layer with a dry fingertip and add water if it feels dry. For onion seeds to grow, the soil needs to stay moist but not sogging. 

If you want small onions, harvest the sprouts when they are 3 inches high, or transplant them if you want them to grow a bit bigger. Transplant the sprouts into a larger pot with more soil and continue to water them until they grow, or plant them in an outdoor garden.

How Long does it Take for an Onion to Grow Indoors?

Onions are a cool-weather crop that needs about 90 to 120 days to grow, depending on the type. When you plant green onions indoors from seed, expect to see sprouts within 7 to 14 days after sowing. The shoots grow quickly, but the bulbs will fully mature in about 100 days. 

It’s safe to harvest tops of green onions and scallions when the plant is 6 inches high. The plant and the bulb will grow as long as you leave at least 3 or 4 inches of greenery between harvests. 


Whether you decide to plant bulbs or seeds, growing onions indoors are easy. Onions need a deep container, well-draining soil, regular watering, and a lot of sunlight to grow indoors. 

Growing onions indoors doesn’t protect them from common pests but allows you to keep a closer eye on your plants. Practicing crop rotation and purchasing high-quality onion seeds are some ways to keep your crop healthy and pest-free. 

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