Herbs Die after Harvest
You may be removing too much foliage when you harvest. It's always best to harvest sparingly the first year, to give the plant time to become established. Here are some general guidelines to harvesting herbs: Begin harvesting the herb when the plant has enough foliage to maintain growth. Up to 75% of the current season's growth can be harvested at one time. Harvest early in the morning, after the dew dries, but before the heat of the day. Harvest herbs before flowering, otherwise, leaf production declines. Herb leaves have their most intense oil concentration and flavor when harvested after flower buds appear but before they open. Herb flowers harvested to dry for craft purposes should be picked just before they are fully opened. Annual herbs can be harvested until frost. Perennial herbs can be clipped until late August. Stop harvesting about one month before the frost date. Late pruning could encourage tender growth that cannot harden-off before winter. Harvest tarragon or lavender flowers in early summer and then shear the plants to half their height to encourage a second flowering period in the fall. Hope your next attempt is more successful!