About
Costmary (*Tanacetum balsamita*) is a clump-forming perennial herb to about 1 m tall with thick, balsam-scented leaves that were once used to mark Bible pages and flavor ale. Leaves are oblong, finely toothed, and slightly resinous; summer brings yellow button flowers in loose clusters. It behaves like a hardy chrysanthemum relative. In subtropical and tropical Americas it may struggle in constant tropical heat—grow in bright shade with rich soil and steady moisture, or treat as a cool-season annual replacement in the hottest lowland sites. ☀️💧 **Sun and Water Requirements:** Morning sun and afternoon shade in warm climates; full sun only where summers are mild. Even moisture with good drainage; mulch to buffer soil temperature but keep mulch off crowns. ✂️ **Methods to Propagate:** - **Division:** Split crowns in early spring or fall; replant immediately. - **Root cuttings:** Take thick roots in dormancy, bury horizontally in moist mix until shoots appear. 🌾 **When to Harvest:** Gather young leaves before flowering for freshest flavor in teas and flavoring; dry leaves in loose bundles out of direct sun for winter use. Flowers can be trimmed to prolong leaf quality.
Permaculture Functions
- **Edible: ** Aromatic leaves flavor drinks and sweets where traditional costmary recipes still survive.
- **Medicinal: ** Historically used as a mild digestive bitter; modern use should stay conservative and well researched.
- **Ornamental: ** Bold foliage and yellow buttons fit cottage borders and herb spirals.
- **Pest Management: ** Strong scent can confuse or repel some chewing insects when interplanted in mixed beds.
Practitioner Notes
- Leaves smell balsam, not tansy-tea classic—taste-test small before big culinary substitutions.
- Tall second-year bloom stalks need support in rain—stake or cut for bouquet before stems kink.
- Divide in spring—crowded clumps go hollow in center and invite mildew between leaves.
- Whiteflies love stressed greenhouse plants—yellow traps catch adults; wash larvae off undersides early.
Companion Planting
- Rue
- Hyssop
- Chives
- Calendula
Pest Pressure