A while ago, I picked up a seed catalog and began to thumb through the sections.  I landed in the tomato seeds portion.

Heirloom, hybrid, grafted, there seemed to be a variety of varieties.

And in and amongst the varieties, I found determinate and indeterminate and many of the varieties were peppered with letters trailing their names; VF, VFF, FFT, VFNT.

What does this all mean?  Determinate and indeterminate are actually general botany terms and are not limited to tomatoes, but are often associated with them.  Determinate tomatoes are those tomato varieties that have a short, compact form and usually have all their fruits mature at the same time.  Some determinate plants will taper their fruit growth after the main burst; others will simply die off.

Indeterminate plants, in contrast, are the vining variety of tomatoes.  They keep growing and producing fruits throughout the growing season.

There is also a newly created characteristic called Indeterminate Short Internode (ISI). It combines the growth characteristics of a determinate – shorter, more compact – with the all-season-long fruiting characteristic of an indeterminate.

Now, all those letters.  They stand for the disease or pest resistance characters.

V Verticillium Wilt Soilborne fungus – Verticilliurn albo-atrum
F Fusarium Wilt Soilborne fungus – Fusarium oxysporum
FF Fusarium Wilt, Races 1 & 2 Soilborne fungus – Fusarium oxysporum and pathogenic variabilities 1 & 2.
N Nematodes Parasitic plant roundworms – Meloidogyne spp
T Tobacco Mosaic Virus Positive-sense single strand RNA virus effecting plants in the nightshade family.
A Alternaria Stem Canker Fungus – Alternaria alternata f. sp. lycopersici
St Stemphylium Gray Leaf Spot Fungus – Stemphylium solani