Why do baby plants (vegetables in particular) just shrivel up and die with no apparent reason?

Question

I planted some vegetables such as cabbages, pumpkins, tomatoes, and zucchini and, they did well at first. I transplanted them into small Jiffy biodegradable pots, and they seemed to thrive in those too. Then their roots started to grow out of the pots, which I thought was normal. I decided, since the roots had grown out of those pots, that I would plant them in the 5 inch Jiffy pots. The plants did fine for about a couple weeks, but eventually their leaves began to turn yellow. It started with the original seedling leaves and then spread to the adult leaves. After the yellow stage they began to shrivel and turn brown. Gradually they fell off, and sometimes the whole plant died. Why is this?

Answer 1

Welcome Wyatt

I too made the same mistake of relying upon these Jiffy type coir+polymeric outer mesh things for my planting and I found them to not only be determinedly resistant to decomposing, the substrate itself was hydrophobic and additionally very compacted meaning that baby roots found it to be a poor medium for growing and my experience was the same as yours.

I found that the roots find it difficult to grow beyond the polymeric mesh and it acted like a corset. These days I tend to use more simple seed trays filled with my own seedling mix and it works better, though pricking out and transferring them to larger posts can be problematic. The alternative would be to use seed trays with compartments or as many people have successfully tried, store up your empty toilet rolls, folding them inwards at the bottom and putting your own seedling mix into them. The cardboard most certainly breaks down more easily and the additional volume means you can go straight from toilet roll to ground, avoiding the extra stress of a second transplant.

I used the Jiffy things when I first moved to my house 5 years ago and when all my seedlings died as you described, I decided to dump the ovaloid things into some felt sacks for growing potatoes, working on the basis they would break down and add some organic material to the grow-sack.

You will not be surprised that whenever I have cropped my potato harvest, every year, the entire oviod bag thing is still there. I put it back in the grow-bag with more compost to over winter each year. The last time I did this was in October 2022 and sure enough, those jiffy bag seedling things were still there in the mix and most certainly not decomposed 4 years later. They were and still are useless.

I have also tried the egg-box type pots by many manufacturers which you fill with your own substrate mix and they too do not break down well and again, despite discarding those into a raised bed to compost down, 2 years on, they are still recognisable complete with the marker pen with the name of the tomato seed I wished to grow. Again, I do not believe them to be decomposable in any reasonable time frame and they can also act as a wick, drawing water away from the seedling in the same way a terracotta pot does.