I've never grown onions before. I bought some seeds about a week ago and I'd like to set up part of a bed to grow onion sets this year. I'll take about 1/4 of my seeds and plant them this fall to get seeds next year. I'll grow the other 3/4 of the onions from seed next spring. I'm in zone 5, and I'm not finding any information on how old onion sets should be when they are dug up this year. I'm thinking they should be a few months old. These will all be long day onion varieties. Thoughts?