Rosemary plants and I have a complicated relationship. I adore them, but they only love me in passing.
I love slow cooking whole chickens with this herb and farm fresh butter. Rosemary is lovely with chamomile and lavender, hung above children’s beds to bring happy dreams. Furthermore, I carried it at my wedding to carry good luck into my marriage.
But for all their good fortune, rosemary plants rarely grow well for me. In fact, the old saying “rosemary thrives where women rule” is true in my garden as well. My husband is the more outgoing and take-charge half of our marriage, and my rosemary plants know it.
In my garden, it never grows lush and full, as my sister-in-law’s plants do. My rosemary rarely grows taller than a foot, while her bushes tower close to 4 feet. Maybe it’s the northern winters, maybe it’s my domestic arrangement. Whatever the case, I’m always trying to start fresh with this herb.
Every year, I take rosemary plant cuttings and root them to start new pots of this healing herb. Sometimes I send them to the houses of more assertive women to be nurtured for a while, before taking them back into my garden.
I’ve even tried growing it from seed, but rosemary seeds are even more picky than the plants. They need time, warmth, and specific soil conditions to germinate at all. Even when seeds do germinate, they’re fragile and often struggle to grow. Taking cuttings is easier and produces quicker results.
If you’re hoping to grow a thriving, aromatic rosemary bush—one that lives every bit of 33 years and grows as tall as a man—you’ll need the right growing conditions on a few different fronts.
The Seed Approach for Cultivating Rosemary Plants
If you want to try starting rosemary from seed, you’ll need to start with sterile planting trays or pots. Rosemary seedlings are notoriously prone to damping off disease. The first month of life is fraught with dangers for this tender plant.
Wash your pots or trays in mild, soapy water. If possible, rinse in hot water with a drop or two of oregano essential oil to resist fungi. Allow your seed trays to dry completely before filling them with fresh, unused, sterile seed soil. Water the soil until it’s wet, but not dripping.
Then, press your rosemary seeds lightly into the top of your seed soil, about an inch apart. You want the seeds to be touching the soil, but not covered by it.
Once all your rosemary seeds are pressed gently into the soil, cover the pot or tray with a layer of clear plastic wrap. This is to help keep in warmth and moisture, but leave one side of the wrap unattached to allow a little air flow. Set the tray in a dark, warm room, preferably on a heating pad.
Rosemary seeds rarely germinate when the soil is under 80F. Ideally, keep the soil between 85 and 90 degrees, and the room at least 75F. Check the seed trays daily to make sure the soil stays moist, and no mold is forming.
If the soil looks dry, mist it gently to avoid disturbing the seeds. When your seedlings start to emerge, move the trays to a bright, sunny spot. Keep the temperature above 80 degrees and remove the plastic covering. When your seedlings are about 2-3 inches tall, you can transplant them to individual pots.
Even under the best conditions, only about 30 percent of rosemary seeds will germinate. They take anywhere from 15 to 25 days. This herb’s indifferent germination rates make it very challenging to start from seed. You can do it but it’s rarely worthwhile: there’s a much easier way to grow a rosemary plant.
Tips for Successful Seeding
There’s not much you can do to make rosemary seeds sprout better, besides offering them ideal conditions. But there are a few old wives’ tales that offer hope of a better seeding.
Medieval herbalists recommend planting seeds according to the moon cycle. Herbs grow best when they’re planted during the first quarter after the full moon. Try planting your rosemary seeds right after moonrise about 4 days after the full moon has passed.
Water from Beneath
Once your seeds have sprouted, water the from beneath by setting your seed trays in a small amount of light, oregano leaf tea. This will allow the sensitive seedlings to draw up the water they need. The oregano will help fight dampening off disease too!
The Cutting Approach
Propagating rosemary from cuttings is straightforward and effective. Simply cut a 3-inch branch of rosemary from your plant with clean, sharp shears. Take this cutting from the soft, new wood of young growth—not the hard, woody, mature stem.
Young growth roots quickly, while more mature growth is slower to root and more likely to rot.
When you have a healthy, 3-inch cutting, trim the leaves from the bottom inch and a half. Place the stalk in fresh, watered, well-draining potting soil. Cover the pot with plastic wrap to help it retain moisture and set it in indirect light.
Your room should stay above 70 degrees Fahrenheit for quick rooting. In ideal conditions, the rosemary cutting will root and start producing new growth within 5 weeks. Cooler temperatures will delay rooting by 2–3 weeks. You’ll know within 8 weeks if your cuttings have survived.
Once you see new growth forming, remove the plastic and place your new plant in a sunny spot. Rosemary plants need at least 6 hours of full sunlight a day in order to thrive.
Tips for Successfully Rooting Rosemary Plants
There are a few ways to make the rooting process easier and more effective.
I like to take at least 5 to 8 cuttings at a time and root them in separate, small pots. They’re usually all successful, but if one fails, you have a few back up plants growing strong. There’s no such thing as too much rosemary! But, even if you only need 2 more for yourself, young rosemary plants make fantastic gifts.
If possible, take cuttings in the late spring, when new growth is more vigorous and abundant. Spring cuttings are quicker to take root and generally produce healthier young plants that fall cuttings.
If you do try to root cuttings in the fall, make sure your new plants are getting enough light. Once they’ve rooted, young rosemary plants need consistent access to direct sunlight.
You can use a grow light if the early sunsets and autumn rains aren’t offering enough light to grow by. Remember that rosemary needs at least 6 hours of direct sunlight a day. If your days are a bit dreary, give your young rosemary plants a bright boost of light.
It’s a good idea to lick the base of each cutting before planting it in the potting soil. That sounds strange, I know! But it really works. Commercial root hormone is often too aggressive for rosemary cuttings, but saliva is a tried and true way to encourage rooting. It’s safe, and often more effective than commercial preparations.
In close conditions, especially in cooler seasons, use a warming pad to keep the soil above 70 degrees. Additionally, water your cutting with a light oregano tea to reduce the likelihood of damping-off disease. Rosemary cuttings are less prone to dampening off disease than rosemary seedlings though.
Consistent Results from Cuttings
Along with their low germination rates and fragile seedlings, rosemary seeds produce another frustration for at home growers: excessive variety. Normally, variety is the spice of life, but the variations in rosemary seedlings make the task of producing consistent, healthy plants a daunting one.
If you plant 10 rosemary seeds, it’s likely only three will germinate. Of those three, at least one is likely to die as a seedling. It’s probably you’ll lose two of your young rosemary seedlings. The single plant that survives has a high chance of being stunted, patchy, or low in essential oils.
The truth is, you rarely know what you’ll end up with when planting rosemary seeds. Cuttings, on the other hand, are identical to the mother plant. If the rosemary you cut from was a healthy, aromatic, lush plant, then the cutting will be as well.
It’s comforting to know that your labor will pay off, and cuttings offer a measure of security. All the work of producing new plants won’t leave you with scraggly, dull rosemary bushes. Even if you don’t have luck with rosemary plants long term, your new cuttings will be strong enough to thrive anyway.
Not Just Better, The Best!
Rosemary is worth the effort. Though it doesn’t grow willingly in my garden, few herbs are as worthwhile to cultivate. I coax and entice rosemary to come stay with us as often as I can. It truly does “cause good and gladness and lighten the hearts of all that use it.” It’s a joyful, healing herb with boundless uses in the kitchen, the medicine shelf, and as an aromatic addition to the house.
The best way to propagate rosemary is, without a doubt, the cutting method. Its high success rate and consistent results make starting rosemary a joy.