Worth distinguishing from nitrogen, which also starts on old leaves but yellows the whole leaf evenly including the veins. If your veins are clearly still green, it is magnesium or possibly iron, and iron shows on the new growth at the top instead. Yours is the classic old-leaf pattern.
Melisande Cray
@metronome_mel
Twenty years at the piano, half of them teaching adult beginners in my front room. Practice structure, sight-reading, and how to make slow practice bearable.
If it were herbicide drift you would usually see it on the youngest growth first and on nearby plants that are unrelated species. Worth a walk round the garden to check whether anything else looks strange, particularly if a neighbour has been spraying a lawn.
Basil in full afternoon sun at 30C will wilt regardless of watering, because it loses water faster than roots in a warm pot can supply it. If it recovers by evening and keeps growing, that is transpiration, not drought. Mine gets morning sun only and never wilts.
Good to hear. Should I be putting anything on them in the meantime or just wait?
Two separate things are happening and they need different fixes. The stretching is light: 30cm above the tray with an ordinary shop light is far too far away, and seedlings reach for it. Drop it to 5 to 8cm above the leaves and raise it as they grow. The collapse at the soil line is damping off, a fungal problem that thrives in exactly what you are giving it, a closed humidity dome over damp compost with no air movement. Take the dome off the moment the first seedlings emerge, not when they are established, and put a small fan on the tray for a few hours a day.
The dome is for germination only. Once there is a green shoot the seed has what it needed and every extra day under plastic is a fungal risk.
Second the hand pollination. Also look at when your flowers are open. In real heat the flowers open and close by mid-morning and bees are working whatever is easiest, which by the sound of it is your borage. Nothing wrong with that, it just means you are the pollinator this year.
Ten days to three weeks of apparent nothing is the normal transplant response and it has a boring cause: the root ball was a dense little cylinder of seed compost and the roots have to grow out of it into a completely different soil texture before the plant will spend anything on leaves. Until that bridge is built, it lives on what is in the pot. The pale outer leaves are the plant recycling nutrients out of old tissue to fund the new roots. Keep watering, do not feed heavily, and around day 14 to 20 you will see a new leaf appear in the centre and then it goes fast.
Before you spend anything, dig a hole 30cm down in the bad bed and the same in a good one, and compare what you see and smell. I once spent 40 on a test that said my soil was fine, when the actual answer was a slab of builders rubble 25cm under one corner.
Also check watering consistency. Dry then flooded gives you split roots and blunt tips even in perfect soil. Carrots are boring like that, they want the same moisture all the way through.