Removing leaves or stalks from tomato plants will increase the size of the tomatoes that grow, but will result in fewer tomatoes. Letting your tomatoes grow without any pruning will yield a higher number of smaller tomatoes; either option is healthy for the plant. Some people prefer the larger, sweeter tomatoes that come from a pruned plant, while others choose to let their plants grow unchecked. If you do choose to remove tomato leaves, there are several guidelines you should keep in mind.
Wait for a warm day when the plants are totally dry. Pruning wet plants can lead to infection. Remove any leaves below the lowest truss (cluster of tomatoes or flowers) on the main stem. These leaves are likely to mold or die because they are close to the damp ground and don't get much sunlight.
Remove small shoots that extend from main stalk to curb the plant's growth. Tomato plants have a tendency to grow in many directions, which can lead to weak stalks that don't support ripe tomatoes. This is especially common in vine varieties, but you can curb the growth by pinching off new stems as they appear. Pinch the tender stems between your finger and thumb near the base until they separate from the plant. Do not remove every new stem or the plant might stop growing altogether, instead limit pruning to about half the new shoots.
Remove leaves sparingly, focusing on areas where leaves are dense and overlapping. Get rid of any leaf that cannot absorb sunlight because it's covered by other growth but be sure to leave enough leaves to shelter the tomatoes. Healthy leaves will turn towards the sun; any leaves that do not face the sun are not getting sunlight and should be removed. Leaves should be pinched off near the base or clipped with gardening shears.
Remove all the tips from every growing stem on your tomato plant about one month before the first frost. Pinch off the ends of growing shoots, including the main stem, about an inch below the tip. This directs all the plant's energy to ripening the existing tomatoes, which will give you a ripe final harvest instead of hard green tomatoes when the frost hits.