I would like to know what would be the best keeping onion from seed to grow?
I understand that a onion started from seed will be bigger than a onion from a bulb is this right?
Many of the bigger varieties are not available as sets (small bulbs). But it is variety that determines the potential size. Sets are usually restricted to 4-5 varieties. If you don't wish to start seeds, then plants from a relaible grower like Dixondale or Brown's Omaha are the way to go. Strating the plants from seed takes time but is realtively easy. Copra is popular, as is Patterson.If you prefer a red , Red Wing
How far in advance of planting out do you start your onion seed?
A long time! I start my bulb onions indoors in late Jan and Feb to have stocky seedlings to set out in April. You can start scallions and leeks until midsummer, but varieties grown for bulbs need the first half of summer to make a good crop.
Concur. approximately 8-9 weeks from seeding to transplant. I am in in winter onion country ( short day onions) so they don't grow as fast.
I just direct sowed some. I am not particularly looking for bulbs, realizing that probably it is too late. But we can always harvest them as green onions/scallions . I have some overwintered ones but they are not looking very good, SO FAR.