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Steps
1
Prepare the garden bed by ensuring the soil is well-draining and loose with a pH between 6.5 and 6.8. Mix in a few inches of compost and apply balanced fertilizer before planting.
2
Plant onions in early spring (late April to early May) once the soil can be worked. Ensure the location receives full sun, ideally up to 13 hours a day depending on the variety.
3
For onion sets, create holes 1 to 1.5 inches deep and 4 to 6 inches apart in rows spaced one foot apart. Plant sets with the pointed end facing up and cover with one inch of soil.
Tip: Separate sets and use those smaller than a penny for bulb growth; save larger sets for green onions.
4
Maintain consistent moisture by providing at least 1 inch of water per week. Water if the soil feels dry 1 inch beneath the surface, using a drip system or soaker hose to avoid soggy soil.
5
Apply a second dose of balanced fertilizer 4 to 5 weeks after planting. Place the fertilizer in a narrow band 2 to 3 inches from the plants.
Tip: Avoid hilling soil up around the base of the plant to reduce the risk of disease.
6
Harvest when two-thirds of the dried top leaves have laid over on the ground. Carefully pull or dig them up using a trowel to avoid damaging the bulb.
7
Cure the onions by laying them in a well-ventilated, shaded area out of direct sun for up to 2 weeks until roots and stems are dry and crispy.
8
Store cured onions in a cool, dry location (32 to 45 degrees Fahrenheit) such as a root cellar or unheated garage. Keep them in mesh bags for airflow and do not refrigerate.
Pro Tips
Match onion varieties to your hardiness zone (5-10) and available daylight hours (long-day vs short-day).
To prevent black mold and other diseases, rotate the location of your onion patch each year.
Use a hoe to cut off weed tops rather than pulling them, as tugging can damage the onion's fragile root system.