@Kathy547 You could try an individual bottle. It might work for you needs. You would have to transplant from the bottle pretty quick. That doesn't work for me, sometimes it is end of summer before I get my "babies" transplanted out. I have used half gallon milk jugs in the past. I just planted four seeds in those. Mostly those were vine like items.
As for how many in a gallon jug, it depends. For most seeds I would say I sow about 24. But some bigger seeds/bigger seedlings I only do maybe 10. And things like dianthus I just sprinkle a bunch because I just plant those out in hunks.
I find you just have to experiment. What works for one may not work for another. Try not to take it too seriously.
Happy planting!
