Feeding query

My chillies, peppers and tomatoes have been in there current pots for 5 weeks now, but some of the leaves have started to turn yellow, particularly on the toms. I have read on a previous post about giving them a bit of feed but I thought you only started feeding when first truss has set. Is it ok to feed now? They are not pot bound, the compost is nicely moist and they are in good light position. Don't want to lose them and have to start again

They could need a little nitrogen?

Sulphate of amonia could sort the greenness out, and help the foilage become healthy, but i've never used it before.

You wont want too much nitrogen when the plant is setting fruit though.

It'll be potash all the way!

Baby bio would be fine as the NKP is about 10-5-2 so itll favour leaves with its nitrogen content.