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How to Grow Rosemary

Rosemary is an essential herb for every herb garden. As an evergreen perennial shrub, it provides fresh herbs for your kitchen year-round, and if you learn how to grow rosemary the right way, will continue producing for years to come.

My guide to growing will take you through cultivating robust rosemary plants, from propagation techniques to planting and care tips.

Rosemary growing in a wooden half-barrel.

The low-down

Rosemary (Rosmarinus officinalis) is a member of the mint family with needle-like leaves and a strong piney aroma. It is a perennial evergreen shrub, making it a great addition to gardens for year-round greenery.

Key Characteristics

  • Leaves: Dark-green, needle-like, slightly glossy.
  • Height: Grows up to 4 feet tall in the right conditions.
  • Flowers: small, blue to pink blossoms.
  • Blooms: late spring to early summer.

Growing Conditions

  • Soil: Well-draining, pH slightly alkaline to neutral
  • Sunlight: Full sun (at least 6 hours a day)
  • Watering: Deeply but infrequently
  • Location: Growing in the ground or in pots.
  • Temperature: Hardy to USDA Zone 8.

Varieties of rosemary

There are many different types of rosemary, each with unique characteristics. They are generally classified into two types. Upright varieties like ‘Tuscan Blue’ can grow tall and are perfect for hedges. Prostrate types such as ‘Prostratus’ spread out and make excellent ground cover or hanging plants.

Some varieties are used for ornamental, rather than culinary purposes, and some are more cold-hardy and can survive in cooler climates. Choose a variety based on your climate and garden needs.

VarietyNotes
Tuscan Blue (Rosmarinus officinalis ‘Tuscan Blue’)Upright growth habit, moderate cold hardiness. Strong flavor, good for cooking. Tall plant.
Arp (Rosmarinus officinalis ‘Arp’)Upright growth habit, high cold hardiness. Strong flavor, good for cooler climates.
Prostrate (Rosmarinus officinalis ‘Prostratus’)Prostrate growth habit, moderate cold hardiness. Low-growing, spreads well, good for groundcover or cascading down walls. Ornamental.
Huntington Carpet (Rosmarinus officinalis ‘Huntington Carpet’)Prostrate growth habit, moderate cold hardiness. Dense, low-growing, spreads rapidly, good for groundcover. Ornamental.
Spice Island (Rosmarinus officinalis ‘Spice Island’)Upright growth habit, moderate cold hardiness. Highly aromatic, flavorful leaves, good for cooking.
Gorizia (Rosmarinus officinalis ‘Gorizia’)Upright growth habit, moderate cold hardiness. Large leaves, milder flavor compared to other varieties, good for fresh use.
Blue Boy (Rosmarinus officinalis ‘Blue Boy’)Dwarf growth habit, moderate cold hardiness. Compact growth habit, small blue flowers, suitable for containers or small spaces. Ornamental.
Salem (Rosmarinus officinalis ‘Salem’)Upright growth habit, moderate cold hardiness. Aromatic, blue flowers, good for both culinary use and ornamental landscaping.
Barbecue (Rosmarinus officinalis ‘Barbecue’)Upright growth habit, moderate cold hardiness. Sturdy, straight stems suitable for using as skewers, strong flavor.
Majorca Pink (Rosmarinus officinalis ‘Majorca Pink’)Upright growth habit, moderate cold hardiness. Pink flowers, aromatic foliage, adds color and fragrance to gardens. Ornamental.

When to plant rosemary

The best time to plant rosemary is in springtime after the last frost. This gives the plants enough time to establish before the hot summer months. In warmer climates, where frosts are unlikely, you can plant in the fall, allowing the roots to grow strong over winter.

Transplant young rosemary plants once the danger of frost has passed. If you’re starting from seeds, sow them indoors six to ten weeks before the last expected frost date. Keep the seedlings moist until they’re ready to be transplanted outside.

Where to grow rosemary

Climate

Rosemary prefers warmer climates and is hardy to USDA Zone 8. If you live in a colder area, consider growing rosemary in a pot that can be brought indoors during winter.

Sunlight

Rosemary thrives in a location that receives full sunlight. Aim for a spot where your plant will get at least 6 to 8 hours of sunlight daily. While rosemary can tolerate partial shade, it will have more vigorous growth and better oil production when it consistently enjoys full sun.

If you’re growing rosemary indoors, place it near a south-facing window. Good air circulation is also crucial as it helps prevent fungal diseases.

Soil requirements

Rosemary prefers light, well-drained soil. Avoid heavy clay soils that retain too much moisture as they can lead to root rot.

If your garden soil is dense, consider improving by adding sand or gravel, and organic matter such as compost. Alternatively, consider creating a raised bed or planting in a container.

Ensure the soil pH falls between 6.0 and 7.0. Use a soil test kit to determine the pH and adjust accordingly.

Propagation methods

Growing rosemary from seeds

Starting seeds indoors

If you live in a region with cool, wet springs, it’s best to start rosemary seeds indoors, as the herb prefers well-draining soil and seedlings will not thrive in very damp conditions.

  • Soak the seeds for 24 hours to improve germination chances.
  • Sow them lightly in a tray with moist seed-starting mix, covering them with a thin layer of the mix.
  • Keep the tray covered with plastic wrap to maintain moisture until germination occurs. This typically takes 2 to 3 weeks.

Direct sowing outdoors

If you live in a region with long, warm growing seasons and well-draining soil. You can sow rosemary directly in the ground:

  • Wait until the soil temperature reaches at least 70°F/ 21°C.
  • Sow the seeds ¼ inch deep and 2-3 inches apart.
  • Thin the seedlings to 12-18 inches apart once they develop true leaves.

Growing rosemary from cuttings

Cuttings are another popular method for propagating rosemary, as it allows you to create new plants with the same characteristics as the parent plant. This method is suitable for all climates and is particularly useful for propagating hard-to-find cultivars.

To grow rosemary from cuttings:

  1. Take 3-5 inch cuttings from the softwood (green, new growth) of a healthy plant.
  2. Remove the lower leaves.
  3. Place the cuttings in a well-draining potting mix.
  4. Keep the soil moist but not soggy.

The cuttings should root within 3-6 weeks.

More details: How to Grow Rosemary From Cuttings

Transplanting rosemary seedlings

When your rosemary seedlings have grown to about 3-4 inches tall and have developed a strong root system, it’s time to transplant them to their permanent outdoor location. Here’s how to ensure a successful transition:

1. Harden off the seedlings

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions over a period of 7-14 days. This helps them acclimate to the new environment and reduces transplant shock.

Be mindful of the weather conditions during the hardening off period. If there are strong winds, heavy rain, or cold temperatures, keep the seedlings indoors or provide temporary protection.

2. Prepare the planting hole

Before planting, weed the area thoroughly and remove any debris, and ensure it is moist – give it a light watering if necessary.

Dig a hole slightly larger than the seedling’s root ball. If your soil is heavy or clay-like, mix in some organic matter or sand to improve drainage.

Spacing

If planting multiple rosemary seedlings, space them 12-18 inches apart to allow for proper growth and air circulation.

3. Plant the seedlings

Gently squeeze the sides of the container to loosen the root ball, then carefully slide the seedling out. If the roots are tightly bound, gently loosen them with your fingers.

Place the seedling in the hole, ensuring that the top of the root ball is level with the soil surface. Fill in the hole with soil and gently firm it around the base of the plant.

Plant cuttings or transplants at the same depth they were in their previous container to prevent stem rot.

Aftercare

Water the newly transplanted rosemary seedling thoroughly, providing enough moisture to settle the soil around the roots. Continue to water regularly, especially during dry spells, until the plant becomes established.

Rosemary plant being watered.

Rosemary care and maintenance

To keep your rosemary healthy and thriving, focus on proper watering, fertilization, and regular pruning.

Watering needs

Rosemary prefers soil on the dry side. If it’s in a pot, water it once a week. For plants in the ground, water every week and a half to two weeks. Always check the soil before watering. If the top inch is dry, give it a drink. Be careful not to overwater, as rosemary can suffer from root rot.

Fertilizing

Rosemary doesn’t need too much fertilizer. In the spring, use a balanced, water-soluble fertilizer when new growth starts. Compost or aged manure can also work well for nutrients.

Avoid over-fertilizing, as this can lead to too much leaf growth and reduce the aromatic oils.

Pruning

Pruning not only shapes the plant but also promotes healthy growth and air circulation. Here’s what to do:

  • Regular Trimming: Gently trim rosemary to maintain your desired shape and prevent overgrowth. Keep an eye out for pests and remove any damaged parts promptly.
  • For bushier plants, pinch back the tips of new growth.
  • After flowering: Trim it back after it blooms, cutting away dead or woody stems and shaping it as desired.

Pest and disease management

Rosemary is known for its resilience, but it can still face pests and diseases. Keeping the plant healthy involves proper care and being alert to any signs of infestation or illness.

Common pests

  • Spittlebugs: While not deadly, these pests can weaken your rosemary. You may notice a foamy substance on the plant—this is their telltale sign. Gently wash them off with water if you spot them.
  • Sap-suckers: Small insects like aphids or spider mites can stress the plant, potentially leading to disease. Applying insecticidal soap can help control their population.

Common diseases

  • Powdery mildew: Recognized by its white, powdery coating, it thrives in high humidity. Ensure good air circulation and avoid overwatering to deter its growth.
  • Root rot: If the roots turn black and smooth, it’s a sign of fungal disease. Water only when the topsoil is dry and provide well-draining soil.

Harvesting and storing

Harvest rosemary just before the plant blooms, when the oils are highly concentrated. However, you can snip fresh foliage as needed throughout the year.

Drying and storing

For short-term storage, place freshly cut rosemary in a glass of water on the countertop away from direct sunlight or refrigerate wrapped in a damp paper towel.

When dry rosemary, tie the stems together and hang the bunch upside down in a dark, well-ventilated area. It usually takes about 10 days for the needle-like leaves to air-dry completely.

Once they’re dry, strip the leaves off by running your fingers from the back of the stem towards the tip. Store the dried rosemary in an airtight container, away from light and heat.