How to Plant, Grow and Care For Rosemary
Are you thinking of adding a new herb to your garden this season? Whether growing rosemary indoors or in an outdoor herb garden, these popular plants are quite hardy, and their care is straightforward. In this article, gardening expert and former organic farmer Logan Hailey takes a deeper look at everything you need to know about growing rosemary in your garden this season.
If you want a fragrant, ornamental, and hands-off herb to add to your garden: rosemary is calling your name! This resilient perennial herb is remarkably easy to grow and thrives in zones 7 through 11. With its vibrant purple flowers in the summertime, this evergreen shrub also doubles as a pollinator-friendly landscape plant.
Like its Mediterranean relatives lavender and sage, rosemary is the perfect addition to a drought-friendly garden. It also makes a perfect companion plant and an effective natural pest repellent for garden pests.
Let’s dig into everything you need to know about how to plant, grow, and care for rosemary in your garden this season!
Plant Type Perennial shrub
Plant Family Lamiaceae (Mint Family)
Plant Genus Salvia
Plant Specie rosmarinus
Hardiness Zone 7-11
Planting Season Spring
Plant Maintenance Low
Plant Height 2-5 feet
Fertility Needs None
Temperature 40 to 75°F
Companion Plants Other mediterranean plants
Soil Type Well-drained, slightly alkaline
Plant Spacing 2-4 feet
Watering Needs Low
Sun Exposure Full sun
Pests Aphids, thrips, spittlebug, mealybugs
Diseases Root rot and powdery mildew
Rosemary is a fragrant perennial herb that is evergreen in zones 7 and warmer. It can grow to a large bush up to 4 feet tall and wide, but can also be kept in compact pots.
Rosemary is often grown as an ornamental landscape plant, but it is also a prized edible herb and companion plant for vegetables.
Its needle-like leaves are reminiscent of mini pine trees and have a strong aroma that repels pests from other crops. Its bluish-purple flowers emerge in early summer and attract pollinators near and far.
Rosemary is resilient to:
- Low-nutrient soils
However, it cannot handle poorly drained soils, overwatering, or over fertilizing. Too much water or fertility can predispose the plant to root rot and cause rosemary to lose its infamous smell.
If you notice that your rosemary is lacking in fragrance, it could be a sign that the plant needs more drainage, less water, and/or less fertilizer. When at its best, this pungent, earthy herb has strong tones of sage, eucalyptus, camphor, and evergreen.
Rosemary is native to rocky, dry, warm areas of the Mediterranean. The name rosmarinus comes from the latin word “ros” (dew) and “marinus” (sea) — an ode to its coastal origins.
You can find rosemary growing wild in the hills of southern Europe and Asia minor, as well as northern Africa. It thrives in bright sunshine, well-drained soil, and moderate humidity.
As a Mediterranean native, it shares many of the same growing needs as its relatives sage, lavender, and thyme. All of these perennial herbs belong to the Lamiaceae, or mint family.
Rosemary has many different uses and benefits. This humble shrub can also give your garden a boost by providing:
Pollen and nectar for pollinators
Bees and other pollinators love rosemary’s fragrant summer blossoms. After they feed on the blue flowers, bees are more likely to hop over to your tomato or squash plants to provide pollination services.
Food for hummingbirds
If you love these delightful little birds, rosemary is one of their favorite flowers to feed on in the summer months.
Rosemary repels flies, cockroaches, mosquitoes, slugs, cabbage loopers, and other pesky insects.
Habitat for beneficial insects
Rosemary provides biocontrol benefits because it attracts predatory insects that eat harmful pests from the garden.
Rosemary is primarily propagated by cuttings. Propagation by seed can be difficult. Most gardeners begin their rosemary patch with a plant purchased from a local nursery or garden store, or a cutting from an existing plant.
Either way, remember that it prefers to be vegetatively propagated. Although it can be grown from seed, this is more difficult and requires extraordinary patience.
Germination takes 2 to 4 weeks, and this slow growing woody plant won’t be ready to harvest for a year or more. Unless you have the patience to wait for seeds to grow into full size plants, we recommend propagating by cutting.
Propagation via Cuttings
Rosemary is an easygoing plant to grow and replicate. If you have propagated lavender, sage, or another herbaceous perennial, then this process will be familiar. The best time to take cuttings is in the spring before the plant starts flowering.
If you want to get a head start with a greenhouse or indoor grow lights, plant cuttings indoors 8 to 10 weeks before the expected last spring frost.
- Healthy mother plant
- Glass or container
- Pocket knife
Rooting Your Cuttings
To successfully root your cuttings, follow the steps below.
- Find a non-flowering sprig that is relatively pliable.
- Follow the stem down 6 to 10 inches long and cut just below a node.
- Strip the leaves off the bottom few inches of the stem.
- Use scissors or a knife to shave some of the outer wood from the bottom of the stem.
- This process makes it easier for the cutting to sprout new roots.
- Optionally, dip the woody end of the stem in a rooting hormone solution.
- Place the cutting in water with only the stripped stem portion submerged.
- Keep the rest of the upper leaves above the water line.
- Place the jar or pot in a warm place with indirect sunlight.
Change the water every few days to keep the environment oxygenated and prevent rotting. After 1 to 2 weeks, you should notice root hairs forming in the water.
Colder temperatures or low lighting may delay the process. If the cuttings have brown or dying leaves, it could be a sign that they are rotting or failing to root. Remove them and start over as needed.
It typically takes 4 to 8 weeks for rosemary cuttings to form enough roots to be potted up. You know it’s time to pot up when you can see at least 5 healthy root hairs that are about ½ inch long.
To successfully pot up the plant and allow for further growth, follow these steps.
- Prepare a sandy soil mix that has excellent drainage.
- Cactus potting soil tends to work great.
- Fill a 4-inch pot with the soil and slightly dampen.
- Use a pencil or pen to make a hole in the center that is 3 to 4 inches deep.
- Carefully remove the cutting from the water and place it in the hole.
- Avoid damaging the baby roots.
- Gently “tuck in” the stem and water thoroughly.
- Place the new plant in a warm environment with filtered sunlight for at least 6 hours per day.
- Provide plenty of moisture but be sure not to overwater.
- As the plant gets larger, re-pot as needed.
- Wait until the rosemary is at least 8” tall and thoroughly bushed out before transplanting.
In most climates, rosemary should be planted in the spring after the danger of frost has passed. Whether you are planting in a pot or in the garden, this allows the Mediterranean herb to develop its roots during the warmest, sunniest months.
In zones 9 and warmer, you may choose to plant in the fall so it is not immediately subjected to the intense heat of southern summers. If you choose to plant in fall, ensure that rosemary has ample sunlight to get off to a strong start.
Transplanting a rosemary start is very similar to planting vegetable seedlings. Once you have rooted cuttings or a developed plant from a nursery, you ca
Choose Your Container or Garden Bed
Rosemary is a plant that really doesn’t like to be up-rooted once it’s in the ground. This means that cold-weather gardeners need to prepare ahead of time to protect their rosemary in the winter.
If you are in zone 7 or colder and want to grow rosemary as a perennial, it is best to plant it in a large pot that can be moved indoors. If you want to grow rosemary as an annual or with a low tunnel to protect it in the winter, choose a garden site that is easily covered.
However, if you are in zone 7 or warmer, it will thrive outdoors and doesn’t need to be grown in a container at all.
Choose the Right Planting Site
Find a part of your garden that receives full sunlight and can support the growth of a shrub that may grow up to 4 feet tall and 4 feet wide.
If you are growing other perennial Mediterranean herbs like lavender, sage, thyme, or oregano, it is best to plant them together because they have almost identical growing needs and minimal nutrient competition.
Next, check that the soil is well-drained. Unlike garden vegetables, rosemary does not prefer a rich, compost-heavy soil. Instead, it likes sandy, gravelly, or rocky soils that drain water quickly.
If you want to save yourself some headaches down the line, use the guidelines below to thoroughly amend the soil before planting.
Check the Roots
You should also check that the roots of your rosemary plant are healthy and vigorous. If you give the base stem a light tug, there should be plenty of resistance.
If the plant comes out of the soil easily, it could mean that your cutting has not grown enough roots. On the other hand, if a rosemary plant comes out of its pot with roots winding around in tight circles, this could be a sign that it is rootbound.
You will need to loosen the roots by ruffling them with your fingers or gently pulling apart the lower portions to encourage the roots to reach out into the new soil.
Make a Planting Hole Twice the Size
Use a shovel or a garden trowel to dig a planting hole that is twice the size of the rosemary’s root ball. Loosening the surrounding soil will make it easier for the plant to establish.
Next, hold the plant at the base and gently wiggle it out of its container. Place the rosemary in the planting hole and backfill as needed to keep the top of the plant at the same soil level. Avoid burying or mounding soil and the base of the stem.
Depending on the variety and pruning regimen, most rosemary plants need to be spaced 2 to 4 feet apart. Some plants can spread even wider than 4 feet, so it is best to give rosemary as much space as possible. The herb can be kept in compact containers or smaller gardens if you prune more often.
Although rosemary is very drought resistant, newly planted herbs need a continuous supply of moisture to get established. Water new plants evenly and regularly, about once per week. Ensure that the soil is never overly soggy nor bone dry.
After the first month, rosemary can usually fend for itself and survive off of rainfall. Most gardeners don’t need to install any irrigation systems in Mediterranean herb beds. These plants will only need water during the hottest, driest season.
If growing in a container, give the plant a generous soak until water trickles out of the base of the plant. Then, wait for the soil to dry out before you water again. Stick your finger 4 to 6 inches in the potting soil to check that the lower soil profiles are dried out as well. Overwatering is a bigger threat to container-grown rosemary because the roots can rot more easily.
How to Grow Rosemary
With its lavish aroma and vigorous growth, you would expect rosemary to be a high-maintenance herb. In actuality, this perennial shrub is a garden favorite because of its easy going attitude. Growing rosemary is a hands-off endeavor.
Once the plants have adjusted to their new home, you may find that you only tend to the patch when you are pruning or harvesting.
Full sunlight and warmth are Rosemary’s favorite conditions. This Mediterranean plant grows wild on rocky outcrops by the ocean. This means it cannot handle shade.
Rosemary needs at least 6 to 8 hours of direct sunlight in the growing season. Winter cloudiness or shade are tolerable.
Once established, it prefers to stay relatively dry. This is why it thrives in rocky gardens alongside drought-savvy lavender and thyme. You should not need any irrigation system in your rosemary bed.
Provide continuous water during the few weeks after planting, then let the plant fend for itself. Allow the soil to dry out between waterings and never soak the soil more than necessary. If you use mulch, opt for wood chips or gravel mulch that allows water to easily pass through.
Like most Mediterranean native plants, soil drainage is the most important factor for rosemary’s success. If water pools up on the soil surface, it is a sure sign that the soil does not have enough aeration.
Gardeners in wet regions will want to plant rosemary in raised beds or containers that allows water to freely flow downward.
Add the following for soil health:
- Pea gravel
- Limestone gravel
- Small pebbles
- Horticultural sand
- Low-fertility compost
Rosemary does not grow well in wet, acidic soils. Avoid peat moss, heavy clay, or high-fertility compost. Check that the soil pH is between 7.0 and 8.0 and amend with lime as needed. The slight alkalinity mimics the limestone-rich soils of its Mediterranean home.
Climate and Temperature
Once again, rosemary’s native landscape along the Mediterranean Sea provides plenty of clues about its favorite conditions. The ideal temperature is between 40 and 75°F. Though it can handle temperatures down to 30°F and up to 90°F, harsh weather puts more stress on the plant.
USDA growing Zones 8 through 10 tend to have the ideal climates for thriving plants as long-lived perennials. Some areas of zone 7 can still grow rosemary as a perennial, but anywhere colder will likely need to bring this plant indoors for the winter.
Certain varieties like ‘Arp’, ‘Alcalde’, and ‘Athens Blue Spire’ can tolerate higher elevations and northern climates if they have some winter protection.
Rosemary also enjoys a moderate level of humidity around 45 to 55%. Ultra dry areas may see signs of distress, like dry and dropping leaves. This is most harmful in the winter months when indoor herb gardens may be subjected to drying heaters. It helps to mist with water every few days.
On the other hand, ultra humid areas can favor powdery mildew. The herb can survive in zone 11 if care is taken to mitigate the extreme heat and humidity.
Use wider spacing, provide extra air flow (fans if indoors), and consider dappled shade cloth or plating near trees to help rosemary survive through hot southern summers.
Rosemary does not need any fertilizer. Like lavender, this herb can actually have problems when it is fed too much nitrogen. The leaves may lack fragrance or turn yellow when too much fertility is present in the soil.
Instead, plant rosemary and lavender together in rocky or gravelly soil with low fertility. An annual topdressing of compost or mulch is fine for nourishing the microbial life in rosemary beds, but it’s best to avoid any nutrient-rich amendments.
The only maintenance rosemary needs are an annual or twice-annual haircut. The best time to prune is in the late spring after the flowers have faded. Optionally, you can prune again in the fall about 4 to 6 weeks before the first frost.
Pruning keeps the plant from getting leggy or out of control. It helps maintain the shape of hedges, rounded bushes, or other ornamental landscape designs.
Most gardeners cut back their rosemary by about one-half to one-third of the plant. Avoid cutting into the woody part of the shrub.
Instead, prune back the green pliable stems to encourage the plant to keep its shape and funnel energy into root production. Use sharp pruners or hedge trimmers to ensure that you don’t pull or tug the branches.
It may seem like all rosemary is the same, but different cultivars have been bred for certain uses and specific climates. All rosemary varieties are edible and can be used for cooking, but each cultivar has a different flavor and growth habit.
Some of our favorites include:
|‘Tuscan Blue’||This is the most common rosemary grown at nurseries and is a favorite amongst chefs. It has wider leaves and a very aromatic smell. It can grow 6 to 7 feet tall, depending on your pruning schedule.|
|‘Blue Spires’||This rosemary prefers to grow upright and vertical. It looks similar to a mini Italian cypress tree. ‘Blue Spires’ is favored by ornamental landscapers.|
|‘Prostratus’||This rambling, vining rosemary makes a great groundcover or cascading shrub over a rock wall. It grows just 2 feet tall and up to 8 feet wide.|
|‘Arp’||Among the most hardy of all rosemary varieties, ‘Arp’ is said to survive down to -10°F and stands out amongst its cold-tender comrades. It grows about 4 feet tall and wide, but tends to keep an open habit that needs more pruning.|
|‘Salem’||This compact rosemary is tolerant of cold, wet climates and is a favorite in moist areas of the Pacific Northwest.|
Pests and Diseases
Thankfully, rosemary is naturally resistant to most pests. The bugs that do feed on it usually don’t do enough damage to harm the plant’s growth. But rosemary’s “Achilles heel” is root rot. Overwatering and poorly drained soils can be a deadly combination.
Root rot is a common condition amongst Mediterranean herbs exposed to too much water. The disease attacks the roots and turns them to mush, which can make the plant appear thirsty even when it is practically drowning in water. This is particularly problematic in high-rainfall areas like the Northeast or areas with heavy clay soil like the Northwest.
The symptoms of rosemary root rot include:
- Wilted, droopy foliage
- Browning or yellowing tips (early)
- Whole leaves or branches turning brown, yellow or black leaves (intermediate)
- Dying sections of the plant (advanced)
- Dried, brittle appearance
- Foul smell from the roots
- Roots have a mushy, rotten appearance
Prevention is key because this disease can kill entire plantings. Fortunately, you can save a rosemary plant from root rot if you catch it early enough.
Keep rosemary free of root rot by:
- Improving the soil drainage with gravel, pebbles, sand, grit, and/or perlite
- Avoiding excess irrigation
- Allowing the soil to dry out before watering
- Growing in raised beds or containers
If the plant is already infected, dig it up and prune away the mushy rotten parts of the roots. Re-plant in an extra sandy, dry soil and avoid overwatering.
While rosemary likes moderate humidity, too much water on the leaf surface can cause a moldy or powder-like substance to form. Powdery mildew is a fungal disease that thrives in ultra-humid, high-rainfall environments.
To prevent powdery mildew:
- Take all steps above to prevent root rot.
- Never overhead irrigate.
- Plant in an area with plenty of airflow.
- If you receive lots of rain, space your plants farther apart.
- Prune regularly to keep the plant aerated.
- Apply an organic fungicide or horsetail tea to the leaf surface.
- Plant away from cucurbit plants (squash, cucumbers, pumpkins, etc.).
Aphids, Thrips, Mealybugs, and Spittlebugs
Rosemary’s strong aroma keeps most pests away, but a stressed plant can still fall victim to a few bugs. These crawling, sap-suckers don’t usually kill rosemary.
Instead, they weaken the plant or spread disease like mold. However, spittlebugs (the foamy white clumps that sometimes appear on rosemary) are completely harmless.
The easiest solution to all of these pests is spraying your plant with a generous blast of water and a diluted neem oil. You can also use organic insecticidal soap or horticultural oil.
There is no need to apply pesticides to rosemary, especially if you plan to eat it. In the unusual event of a large infestation, simply prune away the pest-infested parts and throw them in the trash.
Frequently Asked Questions
Does rosemary come back every year?
Rosemary is naturally a perennial plant that can come back year after year in zones 7 through 10. However, gardening zones 6 and colder have harsh winters that can kill unprotected plants. You can maintain a perennial rosemary plant in a cold climate by growing in a container and bringing it indoors for the winter.
How long do rosemary plants live in pots?
This Mediterranean herb is a long-lived perennial that can thrive for 15 years or more. If you want to keep rosemary alive in a pot, it’s important to avoid overwatering and regularly up-pot or divide the plant when it overgrows its container.
Does rosemary need to be cut back?
Rosemary prefers an intense pruning once a year to regenerate the plant and maintain a nice shape. You can cut the branches back by up to one-third of their length in the spring after flowering or in the fall a few weeks before the first frost. As long as you don’t cut into the woody portion of the plant, this poses no risk. In fact, pruning encourages lush new growth and strong roots.
With its earthy aroma, rosemary is a grounding, stimulating, and inspiring herb to grow. It doesn’t ask for much, yet it provides an abundance of benefits to your health and your garden.
The most important thing to remember about growing this classic Mediterranean herb is: Stay true to its roots! Give your rosemary the best care possible by planting in well-drained soil, avoiding excess water, and keeping it in a warm, sunny area.