I have heard people say gardeners are either the rabbit kind or the tortoise kind. To me, a more appropriate analogy is the three bears. Meaning one should not start the garden too early, neither too late, but just right.
Seeds do not come with internal calendars, they come with environmental cues. To be a good gardener, you need to have a good plan in place, then observe the environment and make appropriate decisions to get your veggies out there. With the aid of some type of protection, you should have an easier time to accomplish this. A few things I like to do is:
(1) Feb: start the heat loving plants, ie. the tomatoes, peppers and eggplants early. I start then in early March. These plants need time to get to the size needed to transplant. Tomatoes and peppers should be ready to transplant after Mother's day. Eggplants are best transplanted when the temperature warms up significantly.
(2)March: Radishes, cabbage beets, spinach, peas, baby bok choys and fava beans are cold tolerant, and can be started in early march if you use the Minihooper from New Dimension Seed. Onion sets should be planted as soon as the ground is workable. You will be able to enjoy some of these veggies from 30 days after sowing. Plant them closer together and enjoy the thinning as you go along. This work particularly well for radishes. I pick some of the beet greens and put them in my salads.
(3)May: June should be safe to sow beans. If you have the Minihooper, you can get an early start by sowing them 2-3 weeks earlier. I sowed my on May 12, they now have bosoms on and I think I will be able to enjoy them the first week of July. I also sowed my corn and soybeans (edamame).
(3)May: I planted more cabbage, Chinese Broccoli, and kohlrabi directly in the garden without the minicooper. Also sowed are the Asparagus Beans. I am taking a chance here, they may or may not make it, all depends on how warm the weather is...
(4) I am also taking a chance on cucumbers. The lure of getting cucumbers in July is too great, so I decided to give it a shot again this year. I transplanted them in April, covered them with the Minihooper. I remove the cover when the weather is warm, and finally took it completely off in late May. They are growing ever so slow, but is coming along. The hot days should give them a boost this weekend.