Onions
Onions are an important crop for gardening year round. You can plant onion transplants (bunches), sow directly, transplant seedlings, or plant small starter bulbs called sets.
Plant care & info
For optimum success, plant onions in full sun and well drained soil that is high in organic material. Add high nitrogen fertilizer close to, but not in, the planting area at time of planting for starts, and in March for direct sown seedlings.
As the tops begin to dry out and turn yellow, withhold water so the bulbs mature in dry soil. It’s time to harvest when just a couple green leaves remain at the top. Hang the newly harvested bulbs where they will get good airflow. Avoid dew or rain for a week or two while curing. Proper curing is essential to promote long storage.
Keep onions in mesh sacks to provide good ventilation, and hang sacks where air is dry and cool. Occasionally check for and remove any sprouting or rotting onions. Do not store onions near potatoes, as both will go bad faster.
The size of the bulb depends on the amount of top growth before bulbing starts. Some onions are photoperiodic and bulbing occurs only when the length of day is just right. The day length needed for bulbing differs by variety, but is generally near the summer solstice in Portland. For big bulbs, the best thing you can do is to promote rapid top growth in spring. You can do this by providing consistent conditions and plenty of nitrogen. Under those conditions, you’ll have the largest plant possible when the day length causes the plant to switch from growing to bulbing. Onions planted later than March and before June will never make large bulbs.
