Quick Tips for Growing Onions

Published on
March 6, 2023 11:37:00 AM PST March 6, 2023 11:37:00 AM PSTth, March 6, 2023 11:37:00 AM PST

The question on purchasing and planting onions is: what to plant. The onion plant, the onion set or the onion seed? Why not plant some of all three? They all have a different purpose, and all have a place in your garden.

Onions need full sun and well drained garden soils to do their best. Onions, like other garden vegetables, require an inch of water a week during growing season. 

Onion Seed

Start onion seeds indoors about 4-8 weeks before transplanting. Onion seeds can also be sown directly into the garden as soon as the ground can be worked. Follow the packet directions for planting onion seed. 

Onion Plants

Grown for flavor and size

Plant onion plants two weeks before the last frost date.


  • Dig a shallow trench
  • Lay onion plants against one side about 1” deep and 4” apart
  • When tops get long, shear off couple of inches - short tops promote healthier roots

Onion Sets

Grown for table onions & harvesting (a dry “keeping” onion) 

Onion sets are purchased as small, dormant red, white or yellow onion bulbs that are ready to be planted. Plant onion sets in early spring, giving ample time to grow.


  • Plant sets 2-3” apart and about 3” deep.
  • Pull some early if you wish for green table onions, leave others to grow through the summer for large “keeping/slicing” onions. 


  • Larger onions are ready (late summer) when top of the plant begins to fall over
  • Pull onions and allow to dry in the shade for few days before placing them in storage
  • When onions ready for storage, tie the tops together with string and hang in cool dry area OR cut off tops, leaving 1-1.5” of stem and place onions in mesh bag. Hang bag in cool, dry place
  • Occasionally onions bolt (produce a flower stalk). Once the onion bolts, the quality of the bulb deteriorates and should be harvested and eaten quickly