Once the soil temps are consistent within the 50's you can begin to plant most spring vegie seeds. A few weeks later when the soil temps are up into the 60's and 70's you can plant summer stuff.
Cool season vegies are like most salad greens, peas, onions and cold crops such as cabbage, cauliflower and broccoli--can tolerate temperatures slightly below freezing. I think transplants can (if you start your seeds let's say in styrofoam cups on a sunny window sill) safely be placed into your soil when it's consistently warmer w/ no freezing, etc.
Warm season vegie's are like tomatoes, peppers, eggplant, squash and melons.
I believe your area is zone 6.
Planting your perennials / annuals could easily be planted in May - no danger of frost this time. I believe you want to aim for temps being consistent within the 70's.
All bulbs no matter what zone area are best planted in the fall.
Don't forget to take pics of your garden and share with us all here.
