Before deciding how you want to start your garden, consider how much patience you have (for seeds), how many plants you want in the end, and whether you have established plants to take cuttings from—perhaps a gardening friend will share with you!
Grow from seed
If you want to get a really good crop of rosemary, try starting plants from seeds. Germination rate is close to only 15% to 50%, so you’ll need to plant more than you want to get a good crop. Seeds can take as much as two to three weeks to germinate, and the seedlings will be slow to grow.
Plant seeds indoors eight to 10 weeks before the last spring frost to get a head start on your herb garden. If you’re a little late, don’t worry: A good summer of growth will get your rosemary off to a fine start anyway, and it’s a perennial so it will be back next year if you live in zones 7 to 10.
Fill a container almost to the top with a good seed-starting mix, sprinkle seeds onto the surface, and cover with another half inch of starter. Keep the container evenly moist and provide bottom heat to ensure the optimal soil temperature of 80 to 90 degrees F is maintained.
Once sprouted, as long as the frost date has passed, the seedlings should be hardened off by putting them outside during the day and bringing them in at night for a few days before planting outdoors. Water moderately at this stage, using a mister instead of a watering can.
Some gardeners keep their new seedlings in individual pots indoors in the first year, waiting until the following spring to plant outdoors. This gives you some nice houseplants for that first year!
Grow from cuttings
Because of the long germination period and low germination rate of seeds, your best bet might be to start new rosemary plants from cuttings off established plants.
Clip a 3-inch branch from the stem of the established plant, then trim off most of the lower leaves to 1 1/2 inches up the stem. After applying rooting hormone to the bottoms, plant one or two cuttings in a 3- to 6-inch pot, water and place the pot in a windowsill with indirect sunlight and temperatures between 60- and 70-degrees F.
Cuttings will grow quickly and be ready for outdoor planting in about eight weeks. Transplant outdoors once all chance of frost has passed. Again, some gardeners keep these seedlings indoors for the first year, planting outdoors the following spring.
Grow from plants
Rosemary can be purchased as a plant, and this is a good way to get just a small amount of rosemary into your herb garden. Treat plants the same as you would cuttings, planting outdoors after all chance of frost has passed.
Have you tried growing rosemary from seeds, cuttings, plants, or all three? Which method do you prefer—and why? Please tell us how you get your rosemary plants started.