[linda graham]

Help my tomatoes have started to go yellow on the leaves and the leaves are beginning to curl up whats wrong ?
They are in my poly greenhouse and i have watered them well and fed them. Can someone help me ? can they be saved ?

[Baldy]

Maybe need a photo to make diagnosis easier. If they are leaves on the lower part of the plant then its likely not a problem as that often happens to the 'old' leaves.
If its more general then it could be due potassium deficiency
https://www.rhs.org.uk/advice/profile?PID=456

Pip pip,
Balders

[AnneB]

I expect that the temperatures in your poly greenhouse might be too high during the day.  Is the door closed, or do you leave it open during the day?   It can get very hot and the stress will cause leaves to curl.  Oldest leaves at the bottom of the plant going yellow is normal.

[Goosegirl]

As it is VERY warm at the moment, spray water on your greenhouse floor to damp it down and help reduce the tem inside.

[Headgardener22]

Leaf curl is probably because its too hot, its a defense mechanism against damage.

I've thrown an old sheet over my greenhouse to reduce the sunlight and temperature. Easier than painting the glass with coolglass. OK at the moment as its not windy.

[Nobbie]

I've been damping mine down recently to keep it a bit cooler and it seems to be working as they're looking very healthy. I hadn't realised that tomatoes prefer it a little cooler until the chap from Thanet Earth mentioned it.