Wait, are onions to be planted in the Fall also? I'm zone 5 mind you. I've been planting onion sets in the Spring. Can I plant them in the Fall like garlic? I swear I researched onions before. Also, I like the stutgarter (didn't spell check that) if the variety matters.I use the second knuckle of my index finger to gauge the holes, Probably less than two inches cover the cloves top. That may or may not be right somewhere else! or if your fingers are shorter or longer than mine! Onions are similar done by me from transplants for scallions, or about one inch shallower for my main crop onion bulbs, also from transplants. For direct from seeds I shallow plant them about 1/4 inch deep at most and let them rip and thin /transplant the thinnings! If they are to be scallions from direct planted seeds , I may hill them up an inch or two, to encourage a longer white shank after they get going. I plant my main crop onions in late September or early October here. That is sooner than I do garlic. Learned that by experience at this location and from advice from others.