What can I do to help root-bound cucumber plants?

Question

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.

Answer 1

The fact that you have 3 plants means you can experiment and see what works to learn from the process.

In general it's true that cucumbers don't like to have their roots disturbed, especially not once they are large. Fussing with them at this point is likely to upset them a bit. They also don't like being root bound, so you know that if they stay root bound you will have sub-optimal outcomes.

Do I understand that the material binding the roots is egg carton? If so one solution would be to just focus on getting the egg carton to decompose. If any parts of it are above the surface of soil you should cut those off and put some soil on top. Make sure you keep it wet to encourage decomposers. Luckily cucumbers do well with lots of moisture, so keeping the soil wet will help decomposition of the egg carton and the cucumbers. Egg carton is a carbon-heavy material, so you can add any pill bugs (aka roly-polies or potato bugs) you find in your garden since they like to eat the carbon/cellulose structures. You could also try cutting slices into one egg carton to see if that lets the roots spread out.

I also suggest watching the plants. If they seem to be having problems growing then you could consider taking more drastic action.