How to Grow Onions Indoors

You can grow onions indoors either by planting seeds or re-growing onion bulbs in containers. Most gardeners who plant seeds, transplant them to the garden when the seedlings grow. If planting onion bulbs indoors, you can grow them inside indefinitely.


How to Plant Onion Seeds

Planting your onion seeds indoors give you a jump-start on the season. After a few weeks, your seedling will be ready for planting in your garden. Follow these steps for growing successful onion seedlings from seeds:

  • Prepare your seed flats 10 weeks before planting season.
  • Use a well-draining potting soil.
  • Fill your containers almost to the top with potting soil.
  • Sow the seeds about one-quarter-inch deep and one-half-inch apart.
  • Keep the soil moist but not saturated.
  • Germination takes place in about two weeks, depending on the soil temperature.

When the onion stalks reach four to five inches, you can transplant them to your garden.

How to Grow Onion Bulbs Indoors Using Soil

Many people who don’t have space for an outdoor garden, choose to grow onions indoors. Growing indoor onions takes very little effort, and you’ll always have a delicious supply of green onions on hand. Follow these steps for growing green onions inside your house:

  • Select a container that’s about six-inches deep.
  • Fill the pot half way with well-draining potting soil.
  • Choose young, green onions, also known as scallions from your grocery store. Make sure they have the white bulb attached.
  • Trim off the green onion stems, being careful not to damage the white bulb. Save the stems for using in your recipes.
  • Arrange your bulbs about two-inches apart, pushing themroot side down into the soil.
  • Cover the bulbs with more soil, leaving the stem tops slightly above soil level.
  • Place your container in a sunny location.
  • Keep the soil moist but not soaking wet.

In a few weeks, you’ll have a crop of green onions. You can follow this same procedure with the green onions you planted for an unlimited supply of green onions throughout the year.

How to Regrow Onion Bulbs Indoors Using Water

Another method for growing onions indoors is to use water. With this method, you don’t need any potting soil. All you need is a jar that has a wide enough mouth for your onion bulb to rest on the top. Just add enough water to the jar, so that the bottom of the bulb rests in the water. Place your jar in a sunny location, and add more water when necessary to keep the onion roots submerged.