Experts and BHG readers answer.
What to pinch, when to pinch?
"Herbs can be pinched to keep the plants compact and attractive and to harvest them, but they do not get a meaningful horticultural benefit from pinching otherwise.
There is no need to pinch vegetables at all--they need the leaves to support the plant and shield the fruits from the sun. I have seen veteran tomato growers raise their voices over whether or not pinching tomatoes was required, however, pinching tomatoes is NOT necessary and does not increase yield. You may get larger fruit by removing a few of the smaller tomatoes to allow energy to go to some of the biggest ones, but you will not improve your crop by pinching.
Resist the impulse to over-fertilize your garden--that won't improve your yield, and it can actually increase disease problems.
Keep moisture levels even and weed problems down by using mulch--layers of newspaper will work just fine. Protect tomatoes and peppers from cool weather--in fact, they don't have to be set out until June. Keep your eye out for insects, and hand-pick them as soon as you see them. "