I fit 21 in nursery tray, they'll sit flat once the dirt is in them. Delayed starting the squash for a few days as snowstorm with day long power outage and it was cold. It should switch to a heat spell in a few days, so I'll be more comfortable taking the tomatoes, peppers and eggplants off the heat mats and moving them to just under lights. They can handle some colder temps after sprouting, but we're getting to high 20°s nights which is too cold.