Plant onion starts and potatoes around April 5. Sow the seeds of peas (sugar snap and english) at the same time. If the ground is still frozen, then plant these as soon as the ground thaws.
Start tomatoes, peppers, and eggplants indoors around March 26. Then, around May 31 you should start watching the weather forecast and, as soon as no frost is forecast, go ahead and transplant those into the ground.
Now, for all the summer vegetables like beans, peas, corn, squashes, pumpkins, cucumbers, watermelons, gourds and sunflowers: plant those seeds directly into the ground around June 4, or if your soil is still very cold, once the soil is near 60° F in temperature.
However, our location has a shorter than average growing season. Many summer vegetables need more days to mature than our area will provide. Get a head-start by starting these summer vegetables indoors around May 15, and transplant those seedlings out after the danger of frost is past.