French Tarragon

If you see tarragon seeds for sale, walk away. French tarragon — the only tarragon with the complex anise-licorice flavor that belongs in béarnaise and chicken salad — is sterile and produces no viable seed. What gets sold as tarragon seed is Russian tarragon, a weedy relative with almost no flavor and a tendency to sprawl through the garden like a disappointed houseguest. You must start with a division or rooted cutting from a nursery that knows the difference, and you should smell it before you buy — the scent should be unmistakably sweet and herbal, not grassy or faint.

French tarragon wants lean soil and decent drainage. Planted in rich, moist ground, the plant grows tall and lush but loses much of its essential oil concentration — the leaves turn bitter or bland. A raised bed or a gravelly spot in full sun tends to produce stronger flavor than a well-amended vegetable bed. Water sparingly once the plant is established; it came out of the steppes and adapted to dry summers.

Summer heat is the other challenge. When temperatures climb above 85 degrees for extended periods, the flavor diminishes noticeably — the leaves lose their sweetness and take on a flat, slightly metallic note. There is not much you can do about this except harvest heavily in spring and early summer, before the heat sets in, and then again in fall when the flavor returns. A plant that tastes wonderful in May can taste unremarkable in July.

French tarragon is a perennial, but it declines if left undivided. After three or four years in one spot, the center of the clump tends to die out, and new growth becomes sparse and woody. Dig the plant in early spring every third or fourth year, pull it apart into fist-sized clumps with strong roots, and replant the best divisions. Discard the woody center. This habit of dividing is how the plant has been propagated for centuries — there is no other way.

Harvest by cutting stems back to about four inches above the ground, which encourages bushier growth. The leaves are best used fresh; dried tarragon loses much of its character. Freezing the leaves in oil or butter tends to preserve more of the flavor than drying does. In zones 7 and colder, the plant dies back to the ground in winter and re-emerges in mid-spring — mulch it lightly after the first hard freeze.