Rosmarinus officinalis, more commonly known as rosemary, is a woody, perennial herb that is fragrant, evergreen and native to the Mediterranean. While some gardeners plant a rosemary bush in their garden to harvest the herb, others use it to add beauty and fragrance, without ever using the leaves.
The plant has needle-like leaves similar in appearance to hemlock. It flowers in pink, purple or blue in spring and summer in temperate climates, but may flower constantly in warm climates.
Rosemary may be used in multiple ways in your home and is extremely hardy. This means it fares well both inside and outside, in the ground or in a pot. Although it loves the light, heat and humidity are not a must, making indoor growing easier than other herbs. As an herb it’s mostly used in seasonal dishes, but it is also commonly used as an ornamental landscape planting that has the benefit of being both beautiful and fragrant.
Interestingly, this herb may grow upright or as a trailing plant along the ground.1 As a prostrate plant it offers aromatic ground cover to your garden that may be harvested throughout the growing season. The blue flowers of the trailing rosemary plant are attractive to bees, offering nutritional benefits to you and supporting the local bee population.
While you may consider bees buzzing in your yard a nuisance, colonies are vital to agriculture as one third of the U.S. food supply depends on bee pollination.2 Those plants include avocado, nuts, citrus fruits and berries, to name just a few. Planting and cultivating a rosemary plant is not difficult and may bring you years of seasoning for your kitchen and perfumed landscape pleasure.
Soil pH Is Important to Your Rosemary Plant
The rosemary bush is a woody growth that is easy to plant and care for. It’s probably best to start from cuttings or an established plant, as germinating from seed may take up to three months and harvesting your first herbs from seedlings may take another couple of years.3
Plant growth and watering requirements will depend on the area where it’s planted. When grown in a pot you may bring it in during the winter months to enjoy the aroma and seasoning all winter long. If you are planting it outdoors, remember it grows best in hardiness zones 6, 7, 8 and 9.4 You can find the hardiness zone for your ZIP code by visiting U.S. Department of Agriculture (USDA) Research Service.5
Rosemary loves at least five hours of direct sun during the day and a sandy, loam soil that drains well. The plant does well when the pH of the soil is between 6 and 7. You may purchase a pH soil test kit at your local gardening shop or use one of these two simple at home tests. The pH of your soil is a rating of acidity or alkalinity with 7 being neutral. Before adding any amendments to the soil, start by doing a pH test.
Any additions you do make to move the pH toward neutral should be made in small amounts over time to ensure they work before adding more. The two tests you may try without using a chemical test kit are:6
Vinegar and baking soda
Collect 1 cup of soil from around the area of your garden you want to test. Mix it well. Place 2 tablespoons of the soil in two separate containers. In the first container holding 2 tablespoons of soil add 1/2 cup of white vinegar. If the mixture bubbles, your soil pH is alkaline and above 7.
If it doesn’t fizz, use the second container with 2 tablespoons of soil and add distilled water until the soil becomes muddy. Next, add 1/2 cup of baking soda. If it fizzes the soil is acidic with a pH likely below 6. If there is no reaction, then the soil likely has a pH between 6 and 7.
Cabbage water test
Simmer 1 cup of cut up red cabbage in 1 cup of distilled water on the stove for five minutes. Let it cool for 30 minutes before straining off the liquid, which should be purple/blue in color. The pH of this liquid is 7. Next, add 2 teaspoons of soil to a jar and a few inches of cabbage water. Stir this up and let it sit for 30 minutes. If the water turns pink then the soil is acidic with a pH less than 6; if it turns blue/green the soil is alkaline, with a pH over 8.
According to Mother Earth News, making amendments to your garden soil to reach near neutral pH may be as simple as adding composted material.7
“Raising the organic matter content of soil will usually move the pH of both acidic and alkaline soils toward the neutral range. This is because organic matter plays a buffering role, protecting soil from becoming overly acidic or alkaline.
Finished compost usually has a near-neutral pH, so regular infusions of compost should be the primary method you use to improve soil with extreme pH issues. If your pH readings are only slightly acidic or slightly alkaline, compost and organic mulches may be the only amendments you need to keep your crops happy and your garden growing well.”
Planting an Established Plant or Propagating Your Rosemary From Cuttings
If you have purchased a small plant from the garden store, you’ll want to dig a hole as big as the pot the plant comes in, as demonstrated in this short video. Press on the side of the pot all the way around and on the bottom to loosen the soil and small roots from the side, so the plant and entire root ball slides out easily. Once out of the pot, loosen the soil around the roots and place it in the hole. Backfill the hole with soil and tamp it down to remove air pockets around the roots.
Rosemary plants grow slowly the first year after planting and pick up speed in the next years. If you want to harvest a significant amount of the herb by your second year, you’ll want to forgo a smaller plant and opt for a larger pot.8
In warmer climates they grow quicker, so you’ll want to plant them at least 3 feet apart to allow ample room for growth. If you live in northern climates and commonly experience freezing weather lower than 15 degrees F, you’ll want to grow your rosemary in a pot and bring it in during the winter months.9
While inside, keep the plant in a south facing window and do not harvest if it is not actively growing. By the end of winter the plant may appear a bit raggedy, with dried up needles and sparse stems. However, after hardening off the plant, place it outside and it should return to full health rather quickly.
The hardening process allows the plant to get used to being in full sun and helps prevent shock.10 It’s easily accomplished by setting the plant outside for two to three hours the first day and gradually increasing the time over 10 days until it is outside full-time.
Cuttings are another way of starting a strong rosemary plant in your garden. These plants will establish more quickly than plants that are started from seed.11 Often it will reach usable size in just a few months and will have the same flavor, hardiness and growth of the original mother plant. Select a healthy stem with fresh growth. Avoid stems that have gotten woody as they don’t root as easily. Using sharp scissors, snip it 5 to 6 inches from the tip and take several cuttings to ensure at least a couple that will root.12
Strip off the lower leaves and place it in a jar of water in a warm area away from direct sunlight. Change the water every couple of days with room temperature water to avoid shocking the plant. It takes a few weeks, or longer in colder weather, for the stem to start growing roots. Once roots develop, pot the plant in soil that drains well, taking care to avoid damaging the roots.
Keep the plants out of direct sunlight until the roots are established. Once you’ve planted either a pot or cutting outside, consider watering once a month in the first three months with a seaweed solution to help the plant get established in the soil.13