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Growing Rosemary for its Tantalizing Aroma and Bold Flavor

  • Bob Styer
  • Herbs
Planting Rosemary In A Pot

This is a perennial evergreen herb from the Mediterranean area.  Rosemary is a flavoring for tomato sauces, meats, fish, soups, stews, casseroles, stuffings, mushrooms, roasted veggies, and bread.  Chefs worldwide prefer one type, surprisingly called chef rosemary (or Tuscan blue rosemary).  Most herbs are easy to grow by seed, but propagating rosemary by cuttings is easier.  After growing fresh rosemary in the herb garden, it will last several years after drying.

In ancient Greece, people wore rosemary sprigs to enhance memory and concentration.  Studies show the aroma of rosemary and essential oils lowers cortisol and decreases stress.

Types of Rosemary

Rosemary has many varieties, ranging from bushy plants to ground cover.  Several types grow so large that they can grow as hedges.  Some varieties are hardy perennials down to Zone 4, but most are hardy in Zones 8 – 10.

When grown as a perennial, rosemary can last for decades.  In lower hardiness zones, rosemary grows annually because of the cold winters.

Depending on the variety, rosemary flowers range from white to pink to blue.  The bush varieties tend to have broader leaves and more aromatic oils.  Unlike other herbs with many varieties, all varieties of rosemary are edible.

Tuscan blue rosemary in bloom
Tuscan blue rosemary in bloom

NOTE:  There is a plant that looks like common rosemary, but it’s an evergreen shrub of the heath family.  This “bog rosemary” (moorwort) is native to bogs in northern Asia, northern and central Europe, and northeastern North America.

Bog rosemary is an ornamental shrub, but isn’t true rosemary.  All parts of this plant are poisonous since they contain andromedotoxin.

Here’s a short list of some interesting varieties of rosemary out of the many that are available:

  • Common Rosemary (Rosmarinus officinalis).  This is the rosemary found in kitchen spice cabinets.  It grows up to 30 inches tall and 30 inches wide with grayish needle-like leaves.  The flowers are lavender-blue.  Good for Zones 6 – 10.
  • Tuscan Blue Rosemary.  Many professional chefs favor this type, also known as chef rosemary.  An upright plant with clear blue flowers and red stems, it grows 6 feet tall and 2 – 4 feet wide.  It grows so large that it makes a great privacy hedge.  This aromatic variety is hardy in Zones 8 – 11 and grows fast.
  • Blue Spires Rosemary.  Another tall plant that can reach 4 – 5 feet with a width of 2 – 3 feet.  The leaves are light grey-green with clear blue flowers.  This variety is hardy in Zones 6 – 10.
  • Miss Jessup’s Upright Rosemary.  This variety has pale violet-blue flowers. It stands 4 feet tall with a width of 2 feet and grows best in Zones 8 – 11.
  • Benenden Blue (or Collingwood Ingram) Rosemary.  This variety will grow 24 – 30 inches tall and 3 feet wide.  It produces dark blue flowers and short leaves and is hardy in Zones 8 – 11.
  • Arp Rosemary.  This is a bushy plant that will reach 3 feet high and 3 feet wide.  The flavor is pungent but it doesn’t have a strong scent.  The flowers are light blue, and it’s hardy down to -10o F (Zones 6 – 10).
  • Hill Hardy Rosemary.  This bush variety has denser and brighter green leaves than arp rosemary.  It has large light blue flowers and reaches 3 – 4 feet high with the same width.  This variety likes Zones 6 – 10.

Many other varieties are available with varying sizes, flavors, and aromas.

Would you like to learn about other herbs? Check out our post “The Complete Guides to Growing Culinary Herbs” for links to those articles.

Rosemary flowering at a lake
Rosemary flowering at a lake

How to Grow Rosemary from Seed

Rosemary seeds sprout slowly and have a low germination success rate.  To increase your odds of success, plan on planting four times more seeds than the number of plants you want.

The easiest ways to grow rosemary are to buy live plants or propagate new plants with cuttings.  If you’re up for a challenge, here’s how to grow rosemary from seed:

Cold Stratification of the Seeds

This is something that happens all the time in the natural world.  In late fall, seeds fall to the ground and snow covers them. Many seeds need exposure to cold weather and moisture for a few months. That’s because it’s part of the germination process.

Planting rosemary seeds without cold stratification means the seeds didn’t get that cold, moist dormant period. Because of this, germination could take a long time or never happen.

Here are the steps for cold-stratifying rosemary seeds:

  • A good time to start cold stratification is six months before the last spring frost.
  • Wrap the seeds in a damp paper towel and put the towel in a Ziploc bag.
  • Keep the seeds in the refrigerator for 2 – 3 months.
  • After cold stratification, soak the seeds overnight in warm water before sowing.
  •  Start the seeds in trays or pots with potting mix or potting soil.

If you use potting soil, mix it with vermiculite, perlite, or potting sand to improve drainage.  Please don’t use potting soil that contains peat moss since the soil could be too acidic for rosemary.

Rosemary Tuscan Blue Live Starter Plant, Rosemary Plant
Rosemary Tuscan Blue Live Starter Plant, Rosemary Plant
Price not available
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2024-07-18
Rosmarinus officinalis 'Prostratus', Trailing Rosemary, Creeping Rosemary, Fragrant Plant, Pleasing Ground Cover, ContainerSize: 3' (2.6x3.5'), Winterized 2Day Shipping
Rosmarinus officinalis 'Prostratus', Trailing Rosemary, Creeping Rosemary, Fragrant Plant, Pleasing Ground Cover, ContainerSize: 3" (2.6x3.5"), Winterized 2Day Shipping
Price not available
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2024-07-18
Gaea's Blessing Seeds - Rosemary Seeds - Heirloom Non-GMO Seeds with Easy to Follow Instructions 97% Germination Rate (Single Pack)
Gaea's Blessing Seeds - Rosemary Seeds - Heirloom Non-GMO Seeds with Easy to Follow Instructions 97% Germination Rate (Single Pack)
$4.99
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2024-07-18

Planting Rosemary Seeds

Spread the seeds and cover them with a light layer of potting mix, but not enough to block light.  Rosemary seeds need full sun or a grow light to germinate.  Next, mist the seeds with water until the soil is damp.

Then, place the trays/pots in a warm sunny area or on a heating mat set at 70 – 80o Fahrenheit.  A grow light will work if you don’t have a spot with reliable sunlight.

Cover the trays/pots with plastic wrap or a clear tray cover.  Lift the cover and check the soil often to ensure it isn’t drying out.  Mist it again as needed.

Remove the cover once the seeds sprout in 14 – 28 days (or longer).  At that time, the sprouts should continue growing in a warm area with good sunlight or a grow light.

When the seedlings are 3 – 6 inches tall and the last frost has passed, transplant them to the garden or larger pots.  The garden soil should be well-drained, pH neutral, and loamy.

Rosemary prefers loamy soil and it won’t thrive in dense soil with heavy clay or soaking wet soil.  The plants should get 6 – 8 hours of full sunlight daily. Let the soil dry out between waterings.

Please be aware that rosemary might have a problem with excessive indirect light or shade. This is an herb that thrives in direct sunlight.

If growing rosemary as a perennial, prune it once a year.  This can happen in the fall or after the winter flowers finish up.  Once rosemary matures, the plants can withstand temperatures down to 15 – 20o F.  Some varieties are hardy down to -10o F.

Propagating Rosemary by Cuttings

Take cuttings after the plant flowers.  Cuttings should be shoots without flowers that are 3 – 5 inches long.  Take the cuttings below a branching point or leaf node.

Then, remove the lower third of the leaves and dip the cut end in the rooting hormone.  Finally, plant the treated cutting in compost mixed with 1/3 vermiculite, sand, or perlite.

Please don’t push the cutting into the soil; make a small hole to put the cutting in and then cover it with soil.  The rooting hormone could scrape off if you push the cutting into the soil.

Rooting hormone speeds up rooting, but it’s not always necessary.  Putting the cutting straight into the compost mixture will also form roots.  Keep the soil moist but not soggy during the rooting process.

Another option is to place the cuttings in water until the roots grow and are a few inches long.  Change the water every three days to keep it clean.  Plant the cuttings in pots with the compost mixture once you have healthy rooted rosemary.

While rooting, place the cuttings in a south-facing window or under a grow light.

Roots should form after about four weeks.  You can test for roots by gently tugging on the plants and feeling for resistance.

If needed, put the plants in larger pots containing the compost mixture.  Discard any cuttings that turn brown.

Rosemary will create a large root ball after growing for a while.  When that happens, move the plants to larger containers.  The plants should be ready for their final pot or garden by spring, after the last frost date.

Propagating Rosemary by Root Division

Since rosemary stems are woody, root division isn’t practical.

Propagating Rosemary by Layering

Layering is best done in spring since the stems are more flexible, and they’ll have plenty of time to root.  Start by selecting one or two healthy outer stems from an established plant.  If you’re using two stems, choose them from opposite sides of the plant.

The next step is to dig a shallow trench along each side where your chosen stems are.  The trench should be about 2 inches deep, and the length of the trench will depend on the length of the stem lying in it.

Don’t bury the stem’s top 2 – 3 inches in the trench. It should stick out of the end of the trench.  This end will soon be your new rosemary plant.

Strip the leaves off the stem, but keep the leaves on 2 – 3 inches of the tip.  Slice the underside of the stripped stem in several places with a small sharp knife.  Disinfect the knife with isopropyl alcohol before and after use.  Next, place the rooting hormone on the underside of the stem.

Bend the stem and lay it in the bottom of the trench, ensuring the last 2 – 3 inches are not in the soil.  Anchor the middle of the stem with a forked stick, landscape peg, or bent piece of stiff wire.  Next, refill the trench with soil.  Water the soil at the buried stems often until roots form.

You can check for rootlets by gently digging around the buried stems.  You can do this after several weeks, but the rooting process could take several months.

Separate the new plants from the mature plant by cutting off the buried stem at the mature plant.  Transplant the new plants to wherever you need them.

Harvesting Rosemary

Once a plant shows new growth, you can start harvesting rosemary.  Snip off the sprigs as needed by finding branches at least 8 inches long.  You can cut off the top 2 – 3 inches of these branches.  Avoid taking more than 1/3 of the plant at one time to prevent damage.

Younger sprigs will be more flexible and lighter green.  Older growth will be darker and woodier.  You can use either one, but the younger sprigs could be more fragrant and easier to chop.

Strip off the leaves by holding the top of the sprig and pulling down the stem with your fingers.  Unlike other herbs, you can harvest rosemary even after it blooms.

Storing Rosemary

Wrap fresh rosemary in a damp paper towel and place it in a Ziploc bag or container.  That way, it can stay in the refrigerator for 10 – 14 days.  To freeze rosemary, take the sprigs with the leaves on them, rinse them, and pat them dry.

Cut the sprigs to 6 – 8 inches long and place them loosely into freezer bags.  Rosemary can remain frozen for 4 – 6 months for peak flavor.  After staying frozen for 1 – 3 years it’s still good, but the flavor will fade.

Dried rosemary isn’t as aromatic as fresh, but it will last several years.  To dry it, put the sprigs on a plate or tray and place them in a cool, well-ventilated area for several days.

Remove the leaves when they’re dry and put them in air-tight containers.  You can grind dried leaves into powder using a spice grinder or mortar and pestle.

To dry rosemary in a dehydrator, first place the sprigs in a single layer on the dehydrator trays.  Follow the dehydrator instructions for drying herbs.  After drying, remove the leaves and place them whole or powdered in air-tight containers.

Rosemary Companion Plants

  • Rosemary repels cabbage worms, cabbage loppers, carrot flies, and bean beetles.  That makes it a good companion for carrots, beans, and cole crops.
  • Deer and rabbits don’t like rosemary either.
  • Herbs that are friendly with rosemary include lavender, oregano, sage, bay laurel, and thyme. All those herbs have the same growing conditions.
  • Strawberries and rosemary benefit each other with increased fertility.  Rosemary protects the strawberries from pests. And it also improves their flavor.
  • Onions and rosemary act as a pest repellant team, and rosemary enhances the taste of the onions.
  • Rosemary protects many other vegetable crops from pests.
  • Don’t plant rosemary near basil, mint, tomatoes, or cucumbers.   All these plants need more water than rosemary.

See a complete list on our Companion Planting Chart.

Pests and Diseases of Rosemary

Rosemary doesn’t have many problems with pests and diseases.  The key is to grow it in well-drained soil with good air circulation.  Overwatering or boggy soil can cause root rot.

To control pests like rosemary beetles, aphids, spider mites, mealybugs, or scale, use neem oil or organic insecticidal soap.  Rosemary beetles are large enough to remove by hand.  You can also remove most pests by spraying them with water.

Final Thoughts

Rosemary is one of those staple herbs that’s in nearly every kitchen.  It also serves as an all-around companion plant for your garden. It improves the flavor of some veggies, attracts beneficial insects, and repels pests.  Not only that, but it also works as a decorative plant in your flower beds or inside.

Last update on 2024-07-18 / Affiliate links / Images from Amazon Product Advertising API

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Bob Styer

As a child, I hated gardening. That was mainly because Dad expected us to work in the garden every so often even though we thought play was more important. Over the years, though, I've developed a real appreciation for growing things. Whether you're growing plants for food or to enjoy their beauty, gardening can make your life better. Seize the moment!

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