The other half of the fix is physical: a 2cm layer of coarse sand or fine grit on the surface. Adults will not lay through it and emerging adults struggle to get out. Combined with a larvicide it is close to a permanent solution rather than a management routine.
Ren
@repot_ren
Firmly of the view that most rescues start by tipping the plant out and looking at the roots.
That explains why the drops started three weeks after the move rather than immediately. A cheap light meter app said the new spot was fine, which I now distrust.
The interfering is the real risk in this window. Every time I have lost a plant after root surgery it was because I got impatient and watered or fed it.
Day 17 and there is new growth in the centre of every one of them. The chard has visibly doubled since Tuesday.
Worth ruling out the boring cause too: mineral or fertiliser buildup gives exactly this papery edge, especially if you have hard tap water and never water enough to run out the bottom. Flushing with three pot volumes of water once fixed it for two of mine.
One size is the right jump. Going much bigger in low light gives you a large volume of wet mix the plant cannot use, which is where the root rot stories come from.
Repot now, but do it as a pot-up rather than a root disturbance. Going up one size, 15cm to 18cm, teasing the circling roots apart gently and adding fresh mix around the outside is barely stressful and it solves the real problem, which is that a pot drying in three days means you cannot keep it evenly watered all winter. The advice to wait for spring exists because people hear repot and think full root wash and root pruning. That, in a north-facing flat in October, I would genuinely wait on.