How to Propagate Your Favorite Herbs, Such as Rosemary, Mint, Basil, and More
Not only are herbs low-maintenance plants you can grow—and eat—at home, certain types are easy to propagate, too. "Propagating is the process of growing multiple plants from one single plant," says horticulturist Daniel Cunningham of Rooted In. "Most people have propagated plants by saving and/or planting seeds, but you might not know that most plants can be propagated by taking a cutting from a 'mother' plant."
While short-lived annual and biannual herbs such as dill, cilantro, parsley, chervil, salad burnet, fennel, and calendula are easy to grow from seed directly sown in containers or into a garden bed, Susan Betz, author of Herbal Houseplants ($24.99, amazon.com), says cuttings are a reliable way to propagate unusual varieties that have been developed through hybridization or mutation. "Plants reproduced this way are identical to the parent," she explains. "Cuttings can be taken from the leaves, shoots, or roots of a parent plant."
Interested in learning more about the different ways you can propagate herbs at home? Our experts share their advice for seamless propagation.
Divide the roots of perennial herb plants.
According to Sue Goetz, author of Complete Container Herb Gardening ($18.99, amazon.com), most herbs with fleshy, clump-forming roots are easy to propagate by division. "Simply break a mature, healthy plant into parts without damaging the roots or base to create smaller, individual plants," she explains. "The best candidates are perennial herbs that die back and go dormant in the winter, such as bee balm, mint, lemon balm, and chives."
For the best results, Betz recommends using the root division method to propagate plants in the springtime. "This way, newly separated plants will have ample time to establish a solid root system and healthy foliage over summer," she explains.
Cut off a small piece of an existing plant.
Betz says snipping off a piece of a parent plant, and putting it into soil or water to grow roots, is one of the easiest ways to propagate new herbs. "Look for tender growth with three or more nodes (the place where new leaves emerge on the stems)," she advises. "Your cutting is best as a two-to-six-inch piece of stem that includes a terminal bud (the bud at the very end of the stem)."
Propagate an herb cutting in a glass of water.
Before you can plant and propagate an herb cutting in soil, Goetz says it has to grow roots. "You can root some herbs, especially moisture-loving ones such as those in the mint family, in water," she says. To root herbs including basil, mint, lemon balm, lemon verbena, and pineapple sage in water, Christopher Landercasper, director of farming operations for the Sonoma's Best Hospitality Group, says to cut a six-inch branch that has not yet flowered from your 'mother plant,' and place it into a glass with about two inches of clean water. "Place it on a window sill and after one-to-four weeks, you should start to see root development," he says. "At that point, you can plant it in soil."
Propagate drought-tolerant herb cuttings, like rosemary, in a growing medium.
Many drought-tolerant Mediterranean herbs like rosemary, oregano, thyme, and lavender can be propagated in potting soil. "Instead of placing a cutting in water, you simply poke it into a potting medium to allow the roots to grow," Cunningham says. If you have difficulty rooting certain herbs, or if you want to speed up the propagation process, Betz says you can dip the bottom of the cutting's stem in rooting hormone, before gently inserting it into a container filled with moist potting soil. "Keep the cutting watered well and do not move it from the container until the new roots measure at least one-fourth to a half-an-inch long," she advises. "When roots have formed, cuttings take on a fresh green appearance."
Harden off your new herbs before transplanting outside.
If you plan on moving your newly propagated herbs to an outdoor area, Goetz says they need to be hardened off first. "Hardening off allows new plants to gradually get used to sun and wind exposure, so they can withstand an outside environment." To harden off young herbs before planting them outdoors, Goetz says to take them outside during the warmth of the day and place them in a partially shaded area. "Bring them back indoors at night to protect them from a dip in nighttime temperatures," she advises. "Switch to a sunnier spot after a few days, and continue this indoor-outdoor routine every day for at least a week before planting in the garden or containers."