Determinate tomatoes grow to a specific size and cease growing, using their energy to produce fruit. Although indeterminate tomatoes that continue to grow throughout the season require extensive pruning to maintain shape and size, determinate tomatoes do not require pruning. They do however, benefit from occasional pinching to create a sturdy, compact plant. Clustering tomatoes may require some pinching out of blooms or fruits to allow all fruits in the cluster room to grow and develop.
Pinch terminal ends of determinate tomatoes when plants are young to encourage dense, compact growth. Pinching once transplants begin to show rapid growth improves the shape and appearance of the plant and directs the plant's energy to producing fruit.
Maintain the shape of the plant with occasional pinching of stray branches that disrupt the overall shape. Use care not to pinch branches that have begun to bloom. Determinate varieties produce fruit all at once and removing blooms results in reduced fruit.
Pinch out all but three or four of the best fruits in clusters to allow tomatoes room to grow and develop. Look for fruits that are well-formed, show uniform color and show no signs of disease or insect damage. These develop into the best fruits and should be allowed adequate room to grow.