Stephanie, I might wait just a little bit longer, but our nights are still going below freezing and I just noticed an onion growing in the garden that must have been missed last year, so I actually think you would be okay to plant them -- well, disclaimer, are you planting sets (little bulbs) or plants? I would definitely wait a bit before setting out onion plants, but think you would be okay with sets. Garlic should definitely be okay, I plant that it the fall, same time as I would daffodils, and it survives our winters just fine. (I normally cover it with "floating row cover" - Reemay or the like - or with something like pine branches to hold a good snow cover over it). (I've been in zone 4b for years but the new revised map shows me to be in 5a, so who knows? - I think zone 5 plants are still pretty iffy for our area!)
