Three different types of onion sets are sold every spring at Woodland Gardens.

Three different types of onion sets are sold every spring at Woodland Gardens.

Growing Onions from Sets

You can use onion sets to grow green table onions or large dry onions for storing. Plant onion sets in the spring as soon as the ground can be worked. Plant in fertile, well-drained soil in full sun. Or, they can be grown in a windowbox or patio container if you do not have the space in your garden. Before planting, separate your sets into two different sizes – the larger sets (5/8 – 5/16” in diameter) for green table onions; the smaller (3/8 –5/8”) for dry storing onions.

Green table onions:

Plant these sets at weekly intervals to have a continual supply for the summer. Plant them, roots facing down, in a row or a block. Space them as close together as possible and 2-3” deep into the soil. The deeper you plant the sets, the more tender white stem you will have to eat. You will be able to start harvesting your onions in 4-5 weeks.

 Large dry onions:

Plant your sets in rows or in blocks with their roots facing down and 2-3” between sets in all directions. They should be just deep enough to cover the tops of the sets with soil. Cultivate with a hoe regularly during the season until mature. In late summer the leaves will turn brown and wither; if they turn brown but do not start withering, gently bend the stems over. Once the leaves are dry and brittle, dig the onions up very gently and leave them on the surface of the soil for several days to dry. If it is going to rain while the onions are curing, bring them inside. After the soil on the outside of the bulb has dried, it may be gently brushed off. Store your onions in a cool dry place, out of the light, and with good air circulation. Check your onions regularly and remove any that may have started to rot.