I planted some cucumber seeds in egg cartons and then repotted the best of them twice in coconut coir pots, first a 3" and then a 4" pot. Some of the seedlings had stopped growing and had to be trashed. Three of the plants, though, have done quite well, and another one is doing okay. I have planted the three thriving plants in a 25-gallon fabric raised bed.
The problem is that when I repotted the plants I left them in their smaller pots and just plopped them in the bigger pot and put soil around them. The idea was not to disturb the roots. But I found when I disposed of one of the trashed plants that the egg carton had not decomposed and that the root ball had become bound inside the small egg carton.
I'm afraid the three plants in the 25-gallon container are all root-bound. But they are planted now and I'm not sure if there's anything I can do to help them that will not disturb the roots and make a bad problem worse. I thought about using a small-gauge wire to poke holes around where the egg carton would be to see if that helps the roots grow through it.
Is it worth doing something to try to strengthen the roots or should I just wait and see if the plants somehow make it through on their own?
UPDATE: Unfortunately, these cucumber plants got infected with (probably) the cucumber mosaic virus and I had to remove them. Fortunately, I was able to see that the roots had developed fairly well as they had gone well beyond the egg carton and even the coconut coir pots. Next year I'll try again, and will be sure to plant the seeds directly in soil.