Having had all those problems with weedkiller-contaminated compost over the last few years, I am hyper-sensitive about it now, and I inspect the foliage of my tomato plants very carefully, very often. So far they are mostly looking OK, though I'm a bit worried by this one. One of its leaves has decided to turn upside-down. This might possibly be a symptom of the same old problem.
For future reference the plants were raised initially in Levington's John Innes No.1 compost (seed compost), then in Levington's John Innes No.2 when transplanted to 5" pots, and they are now in Levington's Original Multi Purpose compost. I have deliberately not used any home-made compost, just in case there is still some contamination lurking in it.
Young leaves at the top of a plant are often quite yellowish, like this
I have noticed some slight discolouration and mottling on the leaves of a few plants. This is probably just a mineral deficiency, and if so can be remedied by an application of "Tomorite" or similar tomato food. It's normally considered beneficial to start feeding tomato plants when the first flowers open, so next time they need watering I will give them a feed as well.
Slight mottling on these leaves
As the plants get bigger, they begin to put out side-shoots, which appear in the leaf axils, like this:
Traditionally the side-shoots are removed from cordon-grown indeterminate tomato plants, to help them concentrate on producing a smaller number of bigger fruit, whereas with the shorter bush (determinate) varieties the side-shoots are left in place.
As the cordon varieties grow taller (mine are about two feet tall now), they need tying to their supporting stakes to stop them flopping over.
I use soft jute string and tie them loosely with several turns of the string at intervals of about six to eight inches.
Well, so far, so good then.
