I planted pea seeds almost 4 weeks ago, mid-February. Common wisdom in my area (Pacific Northwest aka Cascadia) is to get your peas in by Washington's birthday (I rarely do). Peas can withstand a fair amount of freezing temps as they germinate. I was about to despair, thinking they'd poked their tender leaves up just long enough for the slugs to have a feast; or that last year's seeds weren't going to germinate; or the birds or squirrels dug them up. Or maybe that long string of frosty mornings was just too much for them. Yesterday I noticed rows of bright green pea foliage braving the outer world.
I protect new seed beds with some plastic fencing - mainly to keep the neighbor cats from using the lovely soft dirt as a giant litter box. It's quite effective; the trick is to take it off before the foliage is too big for the holes! (That's fall-planted garlic at the end of the bed. It will be ready to harvest in June or July.)
In my haste for fresh garden veggies, I also planted lettuce, spinach and chard. I have a nifty little portable greenhouse that I can set up anywhere in the garden. I put it over the seed bed after I planted, and I can zip it up tight for those cold nights. I also tucked in some pots of brassicas (cabbage, broccoli, kale) that I started inside. So far the slugs have stayed away from the banquet I laid out for them.