French Tarragon

Work fertilizer or up to one inch of compost per 100 square feet into the top six inches of soil when you plant, and do not feed established plants after that. Tarragon's flavor intensifies in nutrient-poor soil, so feeding a settled plant buys you lush growth at the cost of the oils you grow it for.

In spring, just as the new shoot tips emerge, lift the clump and separate it with a knife into three to five pieces, each with roots and shoots. Replant 24 inches apart. Renovate this way every two to three years; some sources stretch it to four. French tarragon seldom flowers and sets little viable seed, so it exists only as divisions and cuttings and an undivided clump crowds itself into a woody, thin-flavored center. Utah State Extension calls for renovating every 2 to 3 years to maintain flavor and vigorous growth. Use a knife rather than a shovel or hoe because the roots are brittle and tear.

In spring, once new green growth is pushing from the crown, cut the old dead stems back to the ground. Leave the spent tops standing all winter rather than shearing them in fall. Illinois Extension advises cutting back just as growth resumes in spring, and reports that leaving the tops standing over winter helps improve the plant's overwintering chances. Note that Utah State Extension instead recommends shearing to the ground after frost kills the top growth; either is defensible, but waiting until spring costs you nothing and may help the crown.

Water new plants often until they are established, then cut back to about once weekly and let the soil dry out between waterings. Tarragon is otherwise essentially insect and disease free, so root rot from overwatering or poor drainage is the one thing that actually kills it. The plant wants warm, dry, well-drained ground.

Harvest young stem tips and leaves as you need them all season long. If you want a batch for drying, take the first cutting six to eight weeks after growth begins in spring and a second before fall frost. The anise flavor lives in volatile oils that are strongest in young tips and largely lost in drying, so fresh sprigs cut as needed beat a stored harvest. Freezing chopped leaves in sealed bags holds the flavor better than drying.

Lay a heavy mulch over the plant before winter sets in. Keep it there through the cold and pull it back in spring. When weeding at any season, cultivate shallowly. Tarragon is hardy only to zone 4, and heavy mulch is what carries the crown through in the colder end of its range. Its roots run shallow, so a deep hoe does more damage than the weeds.