Patchouli (Pogostemon cablin) is an herb in the mint family, but its fragrance is very different from spearmint or peppermint. It is used primarily as an essential oil and in perfumes and incense. This tender perennial plant is native to Southeast Asia and is cultivated in India and other tropical areas. It can grow to 3 feet tall and it does well in ordinary garden soil with full sun. Patchouli has been used to repel moths, so if you put a sachet of dried patchouli leaves in your sweater drawer, you can save your garments from the damage these insects can cause.
Grow your patchouli plant as an annual in the garden if you live in an area that receives winter frosts. If you grow it in a pot, it can behave as a perennial if you move it indoors during fall before your first frost.
Pinch off the leaves at the top of your patchouli's branches to encourage the plant to become bushy. You can pinch the plant back as soon as one month after you plant it and dry the tips.
Wait until your plant forms flowers, usually in late summer, before you harvest it for drying. If your area receives winter frost and your patchouli is in the ground, you can pull the entire plant--then snip off the roots. If you live in a tropical climate or if your patchouli plant is in a pot, snip off the flowering tops, including some leaves, but be sure to leave at least two-thirds of each branch if you want your plant to survive the winter and give you more to harvest the following year.
Dry your harvested leaves, flowers and whole plants for seven to 10 days in a warm, dark, dry, well-ventilated area such as your garage.
Tie whole plants and large branches into bundles about 1 inch across at the stem end. String them upside down from a clothesline in a warm, dark, dry, well-ventilated area. Test them after about one week: when the leaves start to fall apart when you rub them, and feel crunchy, they are ready to store.
Dry loose leaves, flower tops and small branches on a screen propped up on wooden blocks or bricks in a warm, dark, dry, well-ventilated area. Check for dryness after five or six days if the area is fairly warm. Otherwise, they should dry within 10 days.