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How to Propagate Rosemary: Tips and Tricks for a Bountiful Harvest

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How to Propagate Rosemary
Photo by Zé Maria on Unsplash

In this article, we’ll cover the steps for how to grow rosemary from cuttings, which is even easier than it sounds. We’ll also cover growing rosemary from seeds as well as the layering method. You’ll learn how to propagate rosemary in water as well as in soil.

Understanding Rosemary

Rosemary is a member of the mint family of herbs. One plant will have several stems, with many needle-like leaves, resembling those of a pine tree. They grow roughly 1 to 1.5 feet tall.

Being native to the Mediterranean, Rosemary likes warm weather and can tolerate dry soil with low nutrients. It doesn’t winter well below -6 degrees C, so it’s often grown in pots in colder regions. Its fragrance is strong, with a smell resembling pine.

Rosemary is part of many popular Mediterranean dishes. It can be used to flavor poultry, steaks, lamb, pork, and fish. Oftentimes, it’s found in soups and stews. You can also use it to flavor vegetables, mushrooms, onions, and potatoes.

How to Propagate Rosemary – The best Techniques

Propagating Rosemary from cuttings is by far the most popular way to multiply your plants.

Stem Cutting Propagation

  1. Find a stem on your plant made of flexible, green material. The hard, woody growth near the base of the plant will snap and is not good for propagation
  2. Cut the rosemary stem about 6 inches long at a 45 degree angle. This angled cut will grow roots better than cutting it straight. 
  3. Strip the leaves off the bottom half to 2/3 of the cutting. This is where the roots will form. 
  4. Option 1: Place your cuttings into small pots with an equal mixture of soil and sand after applying a rooting hormone. Option 2: Set them in a jar of water to root the cuttings and watch for roots to form, changing the water out every 2 days. 
  5. Place your cutting in a window that receives bright but indirect sunlight. 
  6. If you planted the cutting in soil, check for roots after a few weeks by tugging gently on the stem. If you feel resistance, then roots have formed. Water often enough to keep the soil lightly moist. 
  7. Once new growth forms on the plant, you can move it to your garden outside or pot it. Harden the plants off before moving them outside.  

Layering Propagation

Layering refers to the process of growing a new plant while it is still attached to the parent plant.

  1. Choose a tall stem from an existing plant and bend it down to the ground, marking the location. 
  2. Dig a small hole at the location you marked.  
  3. Strip off the leaves of a 3-inch section of the parent stem starting about 3 inches down from the top. 
  4. Place this stripped section into the hole you made about an inch deep and cover it up, leaving the top 3 inches of leaves above ground. 
  5. The stripped section will eventually take root. You can test your rooted rosemary after a few weeks by tugging on it gently. 
  6. Once roots are established and the exposed tip of the stem starts to exhibit new growth, you can cut it off from the parent plant.

Seed Propagation

Rosemary plants are notoriously finicky when it comes to growing them from seed.

  1. Cold-stratify the seeds by placing them in a plastic bag with a damp paper towel. This bag goes in the fridge for 2 to 3 months. Time this process so that stratification is done 6 months before your local spring frost date. 
  2. Once the seeds are stratified and ready for sowing, soak them for 1 night in warm water before planting. 
  3. Sprinkle the seeds over a good seed-starting potting mix in a container with a humidity dome or plastic bag on top. It’s a good idea to plant extra seeds since germination rates are low with rosemary. 
  4. Place your container in a warm location with low, indirect light for about a month. Mist the plants every so often to keep them moist. 
  5. Once the seeds have sprouted, move them under bright light, which could be a window or under a grow light. 
  6. Once the seedlings have reached a height of 4 inches tall, you can transplant them to your garden

The ideal growing conditions

Ideal Soil Conditions

  • Soil pH level: between 6 and 7
  • Soil drainage: well-draining
  • Soil composition: cactus soils that have perlite, pumice, and coarse sand are ideal. A mixture of equal parts sand and potting soil will also work. 
  • Soil nutrients: Rosemary tolerates soil with low nutrient levels.

Optimal Light Conditions

  • Natural light: Rosemary is a light-loving plant and needs full, direct sunlight with no shade. 
  • Artificial light:  If growing Rosemary inside, use full-spectrum grow lights. 
  • Duration of light exposure: 6 hours of full sunlight per day

Watering

  • Frequency of watering: once every 2 weeks, roughly
  • Amount of water required: enough to keep the soil moist without waterlogging it
  • Watering Techniques: Misting the plant every so often is a good idea to keep it moist. Wait until the top few inches of soil have dried before adding more water. 
  • Overwatering: Rosemary is more susceptible to overwatering than underwatering.

Fertilizer Application

  • Types of fertilizers: Any standard plant fertilizer will do the trick. 
  • Nutrient Requirements: Rosemary requires nitrogen, phosphorous, potassium, sulfur, and magnesium. 
  • Application techniques: liquid fertilizer or a slow-release dry fertilizer every month or so.

Transplanting Rosemary

How to Propagate Rosemary
  • Potting the rooted cuttings: If you started a cutting in water, make a hole in the soil with a pencil and place the cutting gently inside. 
  • Growing rosemary in the garden: Rosemary plants can grow up to 3 feet in diameter, so give them adequate space. 
  • Tips for successful transplanting: If you’re growing your cuttings in a jar of water, change the water out every 2 days to prevent rotting. If you grow them in soil, rooting hormone can be used. It’s not essential but it will speed up the process and increase chances of successful rooting.

Caring for your Rosemary Plants

  • Pruning: It’s not necessary to prune rosemary for the health of the plant. Avoid pruning an outdoor plant after 6 weeks before your local fall frost date so it can winterize itself. 
  • Pests and diseases: Rosemary is vulnerable to overwatering, which can cause powdery mildew and root rot to form. Being an aromatic herb, rosemary will repel many insects but is still susceptible to insects like aphids and leafhoppers
  • Harvesting rosemary: When harvesting, use a sharp knife (don’t break stems off by hand!) to slice off stems a few inches long. Only cut-off green, flexible stems.
  • Winter care: Rosemary is not cold-hardy. If you have it in pots, bring them indoors for the winter to prevent damage from the cold. 

Conclusion

Hopefully, you’re now confident in your ability to grow rosemary! Remember to only cut flexible, green stems. Rosemary does not like the cold and it hates being overwatered. It likes a sandy loam and does not need much in terms of fertilizer. Try growing Rosemary yourself and see how easy and rewarding it is.

Best of luck and happy gardening!

Frequently Asked Questions

How do I Propagate Rosemary Cuttings?

The best way to propagate cuttings is by slicing a 6-inch piece of green, flexible stem from an established plant, removing the leaves on the bottom half of the cutting, and placing it in a pot of sandy loam soil mixed with rooting hormone.

How Do I Root Rosemary?

Rooting a rosemary cutting can be done either by applying a rooting hormone and placing it in a sandy loam or by placing it in a jar of water.

Can You Propagate Rosemary Cuttings in Water?

Yes, you can. Be sure to change the water out every 2 days to prevent rotting.

Can I Grow Rosemary From a Sprig?

It can be done as long as the sprig is large enough – if it’s shorter than 4 inches then it may not work.

How Do I Cut Rosemary to Regrow?

Cut a green, flexible stem about 6 inches long. Don’t cut hard, woody stems. Slice the stem with a sharp knife at a 45-degree angle and strip the leaves off the bottom half of the cutting.

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