French tarragon and its Russian imposter
Tarragon grows well in a container, but only for a season. After that, its roots outgrow the pot, and it loses flavor.
French tarragon (Artemisia dracunculus var. sativa), which probably originated in western Asia, is the commonly grown temperate-zone tarragon used for culinary purposes. We grow tarragon for its sweet anise flavor. We clip the leaves into salads and on top of soups. We also use it to flavor sauces (in traditional béarnaise sauce it is an essential ingredient). It is particularly good with shellfish, fish, chicken, and turkey.
French tarragon plants grow up to 24 inches high and 12 inches wide in two years. The leaves are narrow, up to 2 inches long, and have a fresh green color. The flowers are tiny, pale green, and sterile.
Russian tarragon (Artemisia dracunculoides) is very closely related to French tarragon but has no flavor. The Russian species is larger, coarser, and has no culinary merit. It may simply be a genetic mutation of French tarragon, as an experience I once had suggests. I’ve grown thousands of French tarragon plants over a 23-year period, and just this once I discovered a stem on one plant that was obviously different in form. The stem was longer, the leaves were similar in shape but larger and coarser, and it had no flavor—like Russian tarragon. I took the specimen to an experienced botanist who pronounced that it was probably a sport, that is, a spontaneous mutation.
There is also a Mexican tarragon, which is not in the same family as the French or Russian. It is a marigold (Tagetes lucida), grown as an annual in temperate zones and as a perennial in hot climates. The leaves possess aromatic oils similar to those of French tarragon, so, unlike Russian tarragon, Mexican tarragon can serve as a culinary stand-in for French tarragon.