If you have Excel, download the file from the page here linked by justaguy a couple of threads below this one. It'll give you planting dates for common vegetables after you fill in the last frost date.

I'm also in zone 5 (snowing at this moment). Though I haven't been able to look for the last week or so because of the snow that keeps piling up, I believe the green onions from last year are still in the garden and I know the mache is unless the rabbit got it. I'm starting spinach, lettuce (head types) and chard inside, planning on putting them out first of April. I cover the transplants with Remy type row covers and they do fine.
I judge the date by what is sprouting in the garden in the way of 'volunteer' salad greens like the mache, arugula, cilantro, orach, cress, miner's lettuce, and even some regular lettuces...I let a few things go to seed because I never manage to get things planted early enough. That way I can pick salads while planting more for later. One year I even planted tomatoes the first of May under bottomless glass jugs. Of course, that was the year is snowed 5-6" on May 7th. The tomatoes survived with no problem but didn't ripen much earler than if I had planted a couple of weeks later. You have nothing to loose if you plant half you seed, if it doesn't work plant it again later.

Sow the bunching onions indoors under lights. The seedlings are so tiny that direct sowing is difficult or impossible due to weeds. Besides, it's too early to have them out there unless they are under a covered frame or tunnel.

With a frame or tunnel covered with plastic (or rowcover covered with plastic that comes on and off, depending on the weather), you can begin sowing hardy salad greens, though germination may be spotty. For another month yet, do as much germinating as you can indoors, where it's warm, and start direct seeding after the soil loses its chill.

Here is a link that might be useful: my website

So it would be best to start the greens and the bunching onions in flats and transplant out later?

Sow the bunching onions in flats, and sow the greens in about a month. Spinach can be sown now, but actually, if you plan in the future to sow your spring spinach in late September, it'll overwinter and you'll be eating spinach in March before you can sow it in the spring.

I'll be sowing parsley next week.

If you sow kale in flats now it will get off to a running start when you transplant it in mid-April. Make sure you harden it off or transplant under heavy row covers for a few weeks.

Check out this thread about row covers and other season extenders.

Here is a link that might be useful: Row covers

I have no intentions on doing row covers or hoops or anything like that. I just figured since they are cool season crops that I might be able to get away with direct seeding them now and they'll do their thing when the time is right.

Thanks for the info!