Learn how to take rosemary cuttings from an established mother plant and grow new rosemary plants in containers that can be moved outside in summer and indoors in winter.
Rosemary (Rosmarinus officinalis) is a perennial herb in USDA Hardiness Zones 8 and warmer where it can be planted in the garden and can grow 4 feet tall and spreads about 4 feet wide depending on the variety.
For those of us gardening in colder zones, growing rosemary in containers allows us to bring it in during the winter to keep it alive.
My rosemary plant is going on seven years old this year. It grows in a container spends the summer outside on the porch. The rosemary plant is brought inside when the weather turns cold in fall, and it overwinters on a south-facing windowsill.
By the time spring rolls around, the rosemary usually looks raggedy from reduced light and heat fluctuations. Sometimes so many needles dry up and drop off that I wonder if it can possibly survive.
Once warmer weather arrives, the rosemary plant is hardened off, and returned outside for summer. After only a few weeks, it begins to grow new shoots, and the branches fill in with thicker foliage. I am amazed every time it happens.
This is the perfect time to start a new batch of plants. These fresh, green stems are the ones you want to select for softwood stem cuttings.
Benefits of Growing Rosemary Plants from Stem Cuttings
Instead of purchasing a new rosemary plant every year or starting new plants from seeds, try growing your own from stem cuttings. Some of the benefits of growing rosemary from cuttings vs. starting from seeds include:
A rooted rosemary plant from a cutting will mature quicker than a plant started from seed. Rosemary seeds tend to have low germination rates and take a long time to sprout and grow. A rosemary stem cutting will reach a usable size in just a few months, so you will be able to harvest rosemary sooner.
Same as the Mother Plant: The rosemary plant you will grow from cuttings will be an exact clone of the mother plant and have the same flavor, disease resistance, and growth.
Extra Plants for Free: A single plant can provide numerous cuttings without risking the health of the plant. So you can line your kitchen windowsill with several plants that will smell wonderful when you brush your hand against them.
How to Grow Rosemary from Cuttings
1. Select new shoots from the mother plant: Choose healthy stems with fresh growth. The younger shoots will have green stems that are flexible. Avoid older brown, woody stems.
2. Take cuttings: Use sharp scissors and snip the rosemary stem about 5 to 6-inches back from a fresh growing tip. Cut plenty of extra stems in case some fail to grow roots.
3. Strip the lower leaves: Grasp your fingers around the stem, and gently strip off the lower 2-inches of needles from the stem of the rosemary cutting.
4. Place cuttings in water: Stick the stems in a jar of water and place the jar in a warm place away from direct sunlight. Change the water every couple days, replacing with room temperature water. The fresh water provides dissolved oxygen and prevents the cuttings from rotting.
The rosemary stem cuttings should grow roots in a few weeks depending on the temperature. It can take longer in colder temperatures. After 4 to 8 weeks it should be apparent if the rosemary cuttings have survived. The cuttings that do not survive will be brown and shed needles. If your rosemary cutting is still alive, give it some more time.
5. Pot up the stem cuttings once roots develop: Use a sandy soil mix that drains well. Mix equal parts all-purpose potting soil and sharp sand. Or use cactus-potting soil.
Fill a 4-inch pot with slightly damp potting soil for each rosemary cutting. Use a pencil to make a 3 to 4-inch hole into the soil. Place the cutting in the hole with care to avoid damaging the roots. Cover gently and water thoroughly.
Place the newly potted rosemary plant in indirect light or in filtered sunlight until roots become established, and then move to direct light, at least 6 to 8 hours per day. Keep the potting soil moist until you see new growth.
Let the new plants to put on some growth before harvesting. Once the plant is 6-inches tall, harvest by cutting stems as needed. New growth will continue forming on the stem. Rosemary grows slowly so don’t harvest more than 1/3 of the plant at one time.
How to Care for Rosemary Plants
Rosemary is a rather robust plant once it is established and growing. Here are some tips to keep your plant healthy and producing:
Grow in a sunny location. Rosemary thrives in 6-8 hours of direct sun in the summertime.
Water when the soil feels dry. Once established, rosemary likes to stay on the dry side. Allow top inch of soil to dry out between watering, and then water thoroughly.
Re-pot as the plant gets larger and the roots fill the container. A rosemary plant that grows in a container can reach 1 to 3 feet high. Just keep transplanting to a larger container when the roots fill the pot.
Prune rosemary frequently. The more you trim, the bushier the plant grows. Prune the plant after it flowers to keep it compact.
Tips for Growing Rosemary Indoors in Winter
Rosemary is native to Mediterranean climates so it prefers a hot, sunny, and humid atmosphere. Here are some tips for keeping your rosemary plants alive indoors during winter:
Quarantine: If you have houseplants, it is a good idea to quarantine your rosemary plants when you bring them indoors. Keep the plants in a separate location for a while to be sure there are no hitchhikers, pests, or disease.
Light: Locate your rosemary plants in a bright south-facing window. Alternatively, you can use grow lights and keep your plants happy during the winter months.
Water: Try to keep the potting mix evenly moist. Over watering will cause the plant to rot. If the soil is too dry, the plant will wither and die. Water when the soil dries out at the surface and let the extra moisture drain.
Temperature: Rosemary likes it a bit on the cooler side during the winter. Keep the plants away from heat sources and wood stoves. About 60 to 65 degrees is ideal.
Humidity: Winter heating keeps us warm, but it also saps moisture from the air and drops the humidity. Compensate by misting your rosemary plant frequently, running a humidifier, or placing your rosemary plant on a tray of pebbles and water to increase the humidity around your plant.
Pests and Diseases: Common pests for indoor rosemary plants are red spider mites, aphids, spittlebugs, and whiteflies. These pests suck on the plants and cause the foliage to wilt and dry up. Inspect your rosemary plants frequently for pests and control with organic insecticidal soap. Diseases such as root rot, powdery mildew, and mold are all signs of too much moisture and poor air circulation. Allow the top inch of soil to dry out between watering, and then water thoroughly allowing extra water to drain out of the bottom of the pot. Run a fan to improve air circulation around your plants.