Horehound Plants For Sale Marrubium vulgare Herb Growing Tips Light: Full sun Temperature: Perennial for zones 3-10 Watering: regular watering until established- then this plant is drought-tolerant Soil: Can thrive in poor soil but needs to be well-drained soil Herb Description As an ornamental herb, its attractive, fuzzy gray foliage can also be used as a bouquet filler.Horehound tends to thrive in dry, poor soil, so this makes a great herb to dress areas up that may have inadequate conditions. If after a year your Horehound doesn't flower, don't be alarmed. It usually takes this hardy little perennial two years to get full established and start producing tiny purple blooms. A member of the Mint family, it has distinct, wrinkled leaves and a tough fibrous root system. Horehound Properties This herb is still used in soothing lozenge sand cough syrups for congestion and sore throats.