Planting

Onions

Planting Time Onions like to be planted early in the spring. They are tougher than a boot heel. Plant them from seeds, sets (small bulbs), or transplants. If you plant too late in the summer, they’ll bolt instead of making a nice bulb.

Depth & Spacing Plant onion sets about one inch deep and four inches apart. If planting seeds, scatter them then thin to four inches apart. Rows should be a foot apart.

Soil & Fertilization Onions need loose, well-drained soil rich in organic matter. They are hungry for nitrogen early in the season to build big green tops. Too much nitrogen late will make a monster neck and a small bulb.

Watering Needs Onions have shallow roots and need steady water. Give them about one inch of water a week. Stop watering once the tops start falling over for harvest.

Sunlight Requirements Full sun is best. The more sun they get, the better they will bulb. Six to eight hours is minimum.

Harvesting Harvest when the tops turn yellow and flop over. Knock down any tops that are still standing. Cure the bulbs by leaving them in a dry, shady spot for a week or two.

Troubleshooting Watch out for onion maggots, thrips, and purple blotch. Crop rotation is key to avoiding soil diseases.

Captain Greenhouse Tip Onions can be started indoors in flats up to twelve weeks before the last frost. This gives you a serious jump start on the growing season.