Lesson learned: seeds really do germinate when you follow the instructions.
We sowed our seeds indoors in milk crates with about 5 inches of organic potting soil in them. Following our zone's planting guide, we started with spring raab and members of the onion family (red and yellow onions, shallots, scallions, leeks), and added spinach so we could have some early greens. Once our cold frame was ready, we moved the crates and seedlings outside under protection. Our second sowing a week later included the brassica family: cabbages, kales, collards, broccoli and cauliflower.
I assumed that a sowing would yield a few less seedlings than seeds. And most seed packets actually tell you the germination rate (e.g., Blues Chinese Cabbage @ 97%). Whoa... did our seeds sprout! I certainly learned my lesson to sow less seeds in the future because I spent the entire day yesterday transplanting the crowded seedlings into a holding bed - a bed that is full of organic matter where the seedlings will be allowed to mature until we have enough full vegetable beds to plant them out. You should transplant out seedlings once their first real set of leaves appear (not the first 2 leaves, but the 2nd set). Some of our brassicas didn't have this second set, but they were just suffocating in their crates, so I transplanted them anyway. I also ended up transplanting some into proper sowing flats, with dividers for each seedling, so that I could replace any in our holding bed that don't make it.
Another lesson learned: celery and celeriac seeds like a lot of water for germination. I wasn't paying enough attention to these trays and we'll pay for it: we only got about 15 celery seedlings from a sowing of 50 seeds. Now I read John Seymour or go to our seed source's website for every seed I sow to be sure I am doing it correctly (duh). And that's why there's a packet of Shiso seeds in the freezer.
We've got to get double-digging! There will be dozens of plants to transplant after the first of May.