I am just across the border in MN and I planted some of my onions and peas today. I dont grow the other crops you're asking of. I usually plant just part of my early season crops this early, that way if or when we get those Apr. blizzards i don't risk losing the whole works, and if they do survive they will have a head start on the rest which I plant in May. This gives me a safety cushion if it freezes and a more staggered and continual harvest if they do make it.

I would think you could plant any of that stuff where you are, especially if you put a tunnel of coldframe over the beds or rows. I would think you could also plant potatoes, lettuce, beets and spinach if you choose. We usually plant stuff here in about a month--we still have snow on the ground and the ground is still frozen. You can "chit" the seeds--just a fancy word for barely sprout--especially large seeds like the peas. You didn't say whether the onions were from seed or sets/plants. I couldn't plant onion seeds early unless they were bunching onions. If things do get frozen, particularly the leafy stuff, cover the crop or shade it and allow it to thaw in the shade. Often leaves can freeze and can thaw in the shade, but if the sun hits the frozen leaves, you've most likely lost them.

For next year; peas can go in as soon as the soil can be worked. You wouldn't want them in long term snows, but snow contains a lot of nitrogen (which gives the peas a real boost), so up here in Vermont we always hope for a snow AFTER they're peeking out of the ground. Happy Growing!

Radishes!