Sure. They are intended to be removed from the bottom up and they make plug poppers to do the whole tray at one time if you wish.

But all you need is your finger or a wooden dowel, any thing round and that approx. diameter. Water well first, give it a slight push up through the hole and the whole plant pops right out. For it to remain all in one piece the roots have to be well developed.

Dave

Since the cells are still small, they serve only the mid stage of transplants. Good to start seeds, but too small to hold the seedlings.

Well that depends. Those are called plug flats (as opposed to cell packs) and are 38's. So rather than using them for starting seeds they are normally used to grow already germinated seedlings up to transplant size, to 6-8" plug size (thus the name) for planting. That is why they are so deep. But no, if you want 10-12" tall transplants then they won't work that long.

Plug flats come in all sorts of sizes and it is usually the 120's or 240's that are used for germination. The seedlings are then moved into the 76's or the 38's to grow to plug planting size depending on the size plugs desired.

Dave

If I transplant my tomato seedlings to the 38 cell tray, can they stay here until they ready to the field? Or I still need to transplant them again to big pots?

There is no simple yes or no answer to your question. It all depends on how long until you have to wait to transplant them to the field and the growing conditions they have until then. Especially LIGHT.

As I said, plug trays are normally used to grow plants that will be machine-planted (tomato plug planters). So they want plants that are no more than 6" tall, straight stems, no more than 2-3 sets of true leaves, and approx. 6-7 weeks old. That size and age is easy to create within a greenhouse under ideal conditions. So if that size and age is ok with you for transplanting then yes, they will be fine.

But if you want bigger plants for some reason or if it will be another 6-8 weeks before your plants can go out or if your plants get leggy etc. with your growing conditions then they will likely have to be transplanted into pots again. A plug tray can turn into a tangled mess of twisted tops if growing conditions are less than ideal.

Hope this helps.

Dave