What Is a Semi-Determinate Tomato?

Plant Size

• Semi-determinate tomatoes fall in between determinate tomatoes, which grow to a predicted height and then cease growing, and indeterminate tomatoes, which continue to grow taller until killed by the frost in the fall. Semi-determinate tomatoes typically reach heights of 3 to 5 feet.

Blooming

• Like indeterminate tomatoes, semi-determinate tomatoes produce side shoots capable of producing fruit, but production is less than that of indeterminate varieties. Blooming extends for several weeks, but typically does not continue into the fall.

Fruit Set

• Fruit sets on semi-determinate tomatoes over several weeks, producing a variety of tomatoes that mature within a few weeks. Fruit clusters appear between each stem, and the main stem terminates in a cluster of fruit. In contrast, determinate tomatoes set all fruit at once and produce a crop of tomatoes ready for harvest at one time. Indeterminate tomatoes set fruit throughout the season and harvest extends for several weeks to months, depending on your location.

Pruning Needs

• Semi-determinate tomatoes require little pruning beyond what is necessary to keep the plant in shape. Heavy pruning may reduce yield. Remove suckers below the first flower cluster when plants are 8 to 10 inches high. Dr. Helene Dillard and Dr. Steven Reiners, authors of the Cornell University online column "Ask The Plant Doctors," recommend leaving the sucker immediately below the first cluster, but acknowledge that some cultivars thrive if you leave two suckers below the cluster of blooms.