Don't Use Cardboard Roll Inserts With Your Seedlings

This idea of using half a toilet paper center cardboard roll to facilitate both seedling germination and transplant seemed like a useful, clever one.  I saw it on YouTube and gave it a shot...several shots.  In the beginning, it seemed to be working just fine.  By placing the roll in a vertical position in the scooped out hole in the receiving container during a seedling transplant, the process went a little easier.  Later, when watering, the roll appeared to keep the moisture close to the seedling.  All seemed well.  I even recommended the use of the roll in one of my Container Gardening videos here:
https://www.youtube.com/user/ScottHaley12 .  I think it was the "Part 2..." video.

About a month or so later, I began to notice that my tomato plants with the cardboard rolls were beginning to look a bit stunted.  Not all of them were that way, but it was true of the vast majority.  I had lots of plants without the rolls, as well; they were doing much better.  I do like to experiment, but admittedly, this was not a controlled experiment.  In other words, I didn't account for all the possible variables that might result in the stunting of the plants.  The stunting and the cardboard rolls being in the same pots could be nothing but a coincidence.  Nevertheless, I think there's something to this.

Here's what may have happened.  Cardboard contains toxic glue.  There's not a large amount in the center cardboard of a toilet paper roll, but maybe it's enough to affect seedlings.  Water won't dissolve it (release it from the cardboard), but soil microbes will release it when they digest the cardboard.  I'm guessing that's what happened.  My recommendation is:  don't use those rolls.

Happy Trails, & Be Well