Many vegetable, shrub, and tree seedlings come grown in peat pots, also called peat moss pots.
This is very handy, because these pots can go right into the soil which makes it easy to plant large numbers of transplants quickly.
But there is one catch -
when planting out a seedling grown in a peat pot, you need to do one very important thing:
Tear off the top edge before planting!
This should be done because you don't want any part of the pot poking up higher than the soil surface.
If you leave the pot up in the air, it will dry out and act as wick, pulling moisture up and away from the plant's roots.
In fact, many gardeners just to make sure the seedling's roots can transition easily into the garden soil, will also break off parts of the sides and bottom of the pots.