Gardeners further north need long day onions, while those in the south need short day onions. You can also choose between fresh eating and storage varieties!
All onions need full sun-- 10+ hours daily-- to grow well. They also like rich soil that's well draining, and regular watering. Add compost when you plant them for great results!
Whether you're planting onion sets or seedlings, add some compost to the soil and plant them 1" deep, 6" apart. The top of the onion set should be level with the soil.
Onions are ready to harvest when the tops fall over and turn yellow-- but you can harvest them when they're smaller, too! Before storing, set them out of direct light to cure for 1-2 days.
for more tips on onion varieties, plant care, and harvesting for storage