At least I think they are peat.
I'm referring to those 'pots' that we get up here in the Northeast with all types of veggie plants. You're instructed to 'remove the plastic band' & simply plant the entire pot.
That's what I did last year & we had a horrible 'crop' (what little we had). We attributed it to an over-abundance of rain.
This year, I noticed something when turning the soil for replanting this year. Almost all of those 'pots' are intact. Wouldn't it stand to reason that they held back the root growth? Should these 'pots' be slit before planting?