You can use more hashtags, of course, but here are some standard ones:
heirloom_tomato:
* An heirloom tomato breed here is defined simply as one that breeds true (or is true-to-type), without regard to its age.
f1_hybrid_tomato:
* This refers to a first-generation cross between two different kinds of tomatoes.
other_tomato:
* This refers to kinds of tomatoes that don't fit in the other two tags above. For accidental/incidental tomato crosses, mutants, sports, incomplete breeds, and new strains; also, for unidentified tomato varieties.
tomato_growlist:
* This tag is for posts containing lists of tomatoes that you're growing and lists of tomatoes that you plan to grow. Please mention your username and the year in your subject. Optionally, add another tag with the year on the end. This tag has the subdomain tgl.growspice.com.