Fertilize every few weeks with nitrogen to get big bulbs
Cease fertilizing when the onions push the soil away and the bulbing process has started
Do not put the soil back around the onions; the bulb needs to emerge above the soil
Generally, onions do not need consistent watering if mulch is used
About one inch of water per week (including rain water) is sufficient
If you want sweeter onions, water more
Onions will look healthy even if they are bone dry, be sure to water during drought conditions
Make sure soil is well-drained
Mulch will help retain moisture and stifle weeds
Cut or pull any onions that send up flower stalks; this means that the onions have “bolted” and are done
Onion Improved Care:
Select a location with full sun where your onions won’t be shaded by other plants
Soil needs to be well-drained, loose, and rich in nitrogen; compact soil affects bulb development
Till in aged manure or fertilizer the fall before planting
Onions are heavy feeders and need constant nourishment to produce big bulbs
At planting time, you can mix in some nitogen fertilizer, too, and side dress every few weeks until the bulbing process begins
Seeding? Onion seeds are short-lived
If planting seeds indoors, start with fresh seeds each year
Start seeds indoors about 6 weeks before transplanting
Plant onions as soon as the ground can be worked in the spring, usually late March or April
Make sure temperature doesn’t go below 20 degrees F
For sets or transplants, plant the smaller sets 1 inch deep, with 4 to 5 inches between each plant and in rows 12 to 18 inches apart
Think of onions as a leaf crop, not a root crop
When planting onion sets, don’t bury them more than one inch under the soil; if more than the bottom third of the bulb is underground, bulb growth can be restricted