Patchouli is an herb and a member of the mint family. It is most famous as the scent associated with the hippie culture of the 1960s, but it is primarily used in its native Southeast Asia for herbal medications, perfumes, and as an aphrodisiac and insect repellent. The leaves are strongly scented and are harvested, dried and steamed to collect their oil. Aged patchouli oil is much more complex and aromatic than freshly-distilled oil.
Getting the Seeds
Patchouli seeds are tiny and extremely fragile; they can be quite difficult to collect. Three main types of patchouli plants exist: Pogostemon heyeanus, Pogostemon patchouli and Pogostemon cablin. Heyeanus, according to some growers, is the best seed producer. Cablin seeds are available from speciality growers. The seeds develop from the flowers, and the plant may not flower if it does not have the right light conditions. Patchouli is photoperiodic; one way to get it to blossom is to keep it somewhere that is completely dark at night during the fall blooming season.
Growing the Seeds
In late winter or early spring, plant the patchouli seeds in a warm, protected area. For most of the U.S., that means indoor cultivation. The plant likes indirect light; situate containers at the ends of a fluorescent light tube, where the illumination is less intense, or in a window that doesn't get a full blast of afternoon sun. Plant seeds in a mix of peat moss, perlite and vermiculite or in a light, commercial soil that drains well. Dig a hole about an inch square and drop in one seed. Be careful not to bruise or pinch the seeds, as they are fragile. Plant just a few seeds per pot or container; the plants like room once they begin to grow. Cover the seeds lightly with soil, and then water and keep the pot moist, but not saturated. Patchouli grows best in slightly humid conditions. To avoid soaking the roots, keep a tray of water-covered pebbles near the growing plants and let the evaporation increase humidity, creating a microclimate. The seeds should begin to germinate in about three weeks. If the plants start to get leggy, pinch the top off to encourage them to spread out and get bushy.
Harvesting the Seeds
Patchouli flowers are white and purple small blossoms that grow on individual spikes. They are very fragrant -- much more scented than the leaves. Flowers appear in the late fall, followed by the seeds. To harvest the seeds, allow them to dry on the plant and then carefully remove them. The seeds are used primarily to propagate new plants -- only the leaves are used to obtain patchouli oil. Germinating a plant from seed is a slower method for growing patchouli than taking cuttings from a mother plant and allowing them to root in water. However, patchouli, while temperature- and light-sensitive, is not particularly hard to grow, and will thrive for years under the right care.