As I walked up to the seed racks in the garden center I could hear someone talking. “Jet Star VF, Roma VFA.” It sounded like some military code. “Better Boy VFNASt” The woman’s voice continued, “Champion VFNT, indeterminate.” She laughed and pleaded “I give up…are the letters some kind of code? Determinate, indeterminate…what does it mean?”
I laughed and confessed that as a new gardener I thought that VF must stand for “very fast.” But I soon learned that the code had nothing to do with the plant’s growth rate. Instead, the letters indicate disease resistance, while the words “Determinate” and “Indeterminate” tell you how high the plants will get and how they’ll bear fruit.
Many tomatoes are hybrids that have been bred to be resistant to common pests or diseases. For example: A tomato that has the letter “V” after its name is resistant to Verticillium Wilt. Seeds or plants with a “T” are less prone to Tobacco Mosaic Virus. And those that contain an “N” resist attack by microscopic worms called Nematodes.
Now not all diseases or pests are problems in every part of the country. But if you’ve had sick plants in the past you might want to look for the resistant varieties. Your cooperative extension can tell you what problems are common in your area. Or you might just want to choose tomatoes that are the most resistant. These have the longest string of letters after the name.
Now for the rest of the code: a determinate tomato plant that is shorter, and produces fruit over a four to six week period. Indeterminate tomatoes continue to grow, flower, and produce fruit throughout the season. Gardeners who want smaller plants or one large crop of tomatoes for preserving should look for determinate varieties. Those who want to pick a few eating tomatoes throughout the gardening season should choose indeterminate plants.
I usually plant several varieties. No matter what letters come after its name, a freshly picked, homegrown tomato is A-OK with me.
Decoding Your Seed Packet
V – Verticillium Wilt
F – Fusarium Wilt
FF – Fusarium, Races 1 & 2
N – Nematodes
T – Tobacco Mosaic Virus
A – Alternaria Stem Canker
St – Stemphylium Gray Leaf Spot
Determinate – A plant whose stem growth is arrested by a terminal flower that opens before all others. Determinate tomatoes reach a certain plant height and then stop growing, with most fruit borne over a four to six week period.
Indeterminate – A plant whose growth is not halted by a terminal flower. Indeterminate tomato varieties continue to grow and flower throughout the season, but have less mature fruits at any one time.
Indeterminate Short Internode (ISI) – A newly developed type of tomato that combines the controlled growth of a “determinate” with the continual production potential of an “indeterminate.”