It depends how many of a variety I'm starting. I can do up to 75 seeds in a row. I can easily do 150 in one of these containers:
I also sow up to 40 seeds in each square on the 1204 flats.
15 years of doing this and I still tweak the process every spring. All of them go into flats set on shelves with lighting. One 18"x48"x72" plant stand can reliably start 16000 tomato plants, which is more capacity than I've required so far. In practice, a little less than half of my seed starts are tomatoes.
