How to Grow and Care for Rosemary Plants

Rosemary Herb Plant Vegetable Garden, Fresh Green Leaf Sprigs Close-up
YinYang / Getty Images

You don't need an herb garden to grow rosemary. A single plant in a pot will provide you with enough rosemary to flavor your cooking and scent the kitchen. However, if you live in an area where rosemary thrives, you could have whole hedges of the plant.

Rosemary is one of those wonderful herbs that makes a beautiful ornamental plant as well as a welcome culinary seasoning. Its Latin name, Rosmarinus officinalis, means "dew of the sea" and rosemary is most closely associated with the cooking of the Mediterranean area. You don't need perfect sunshine, sea mist, or even a never-ending summer to successfully grow rosemary. In fact, more rosemary plants suffer from too much attention than from too little.

Many gardeners grow rosemary plants simply because they are beautiful plants. Rosemary has evergreen leaves and brilliant blue, creamy white, or pale pink flowers in the spring. While it is not hardy in colder climates, it is easy enough to grow in a pot and bring indoors for winter, where you can still enjoy its evergreen needles and aroma.

Starting a Rosemary Plant

You will make things far easier on yourself if you start with a nursery grown plant. Rosemary can take years to fill in as a plant, so expect to pay more for a mature plant than for a small rosemary start.

If you would like to start your own rosemary plant, the best option is to start with a cutting. Rosemary seed can be difficult to germinate and often do not grow true to their parent. It's much faster to start with a cutting and you will be sure of what type of plant you will get. It's possible to root rosemary in a glass of water, but a bit more effort will give more dependable results.

How to Start a Rosemary Plant from a Cutting

  1. Snip about a 2-inch cutting from the soft, new growth of an established plant.
  2. Remove the leaves from the bottom inch and dip that tip into a rooting hormone. Rooting hormones can be found in any garden center.
  3. Carefully place the dipped end into a container of dampened, sterile seed starting mix. Choose a mix that says it is well draining. A mix containing peat moss with vermiculite or perlite would work well.
  4. Place the container in a warm spot with indirect sunlight.
  5. Mist the cuttings daily and make sure the soil does not dry out.
  6. In about 2 to 3 weeks, test for root growth by very gently tugging on the cuttings.
  7. Once your cuttings have roots, transplant into individual pots about 3 to 4-inches in diameter.
  8. Pinch off the very top of the cutting to encourage it to develop branches.
  9. Begin caring for your cutting as a rosemary plant.

Growing and Caring for Rosemary Plants

The three fundamentals for successfully growing rosemary are sun, good drainage, and good air circulation.

If you live in a frost-free area, you can grow rosemary in the ground year round. It will grow into a lush, bushy shrub. To keep it happy, provide a sandy, well-draining soil and 6 to 8 hours of full sunlight.

Rosemary is not a heavy feeder, but fertilizing in spring with a fish/kelp emulsion will get it off to a good start for the season. Periodic foliar sprays with the emulsion will keep it looking great.

Bringing Rosemary Indoors

Where the winter temperatures dip below 30 degrees F, rosemary plants will have to spend the winter indoors. In this case, it's easier to grow your rosemary in a container all year. Since rosemary likes it on the dry side, terra cotta pots are an especially good choice. Just be sure it doesn't bake and completely dry out while outdoors during the summer.

Bring the potted rosemary inside once the temperature inches into the 30s. It can be a little trickier to keep rosemary happy inside. Your rosemary plant will still require 6 to 8 hours of full sun, so artificial lights may be necessary. Heat is not as crucial as sunlight.

Pests and Problems of Rosemary Plants

The biggest problem with growing rosemary indoors is getting the humidity level right. Too much humidity and rosemary plants have a tendency to get powdery mildew. Powdery mildew is a white, powdery fungus that can develop if the surrounding air is humid and there is not enough air movement. However, too little humidity will desiccate the leaves and quickly kill the plant.

Powdery mildew won't kill your rosemary outright, but it will weaken the plant. Try and balance the humidity by misting the leaves regularly, but allowing the soil to dry somewhat between watering. In addition, keep the plant in sunlight and, if necessary, running a fan for a few hours a day to create a breeze.

Also, be on the lookout for aphids and spider mites. These pests seem to live on houseplants for the winter. Catching them before a total infestation will make them easier to control. Repeated spraying with insecticidal soap, per package directions, should take care of the problem.

Maintaining a Potted Rosemary

Move your potted rosemary back outdoors once all danger of frost has passed.

As with most potted plants, the soil in your rosemary pot will degenerate through watering and root growth. Re-pot at least once a year. Spring is the best time to re-pot your rosemary, but it should be fine no matter what time of year you get to it.

When the rosemary plant puts out considerable growth or looks like it just can't get enough water, it has outgrown its pot and needs to be transplanted into a larger one. If you want to maintain the size of your rosemary plant, root prune it by slicing off a couple of inches of the roots from the bottom and sides of the root ball and replanting in the same pot.

Be sure to trim some of the top at the same time, to lessen the workload of the roots and the stress placed upon the trimmed plant. Then allow your re-potted plant some time to adjust and regroup. It should reward you with many more seasons of snippings.

Great Rosemary Varieties to Grow

True rosemary lover knows there are many subtleties to choose from when selecting a rosemary cultivar.

Flower Color

Rosemary flowers come in shades of blue, pink and white.

  • "Blue Lady" has blue-violet flowers and a wonderfully twisted growth habit.
  • "Nancy Howard" is another large plant, but with off-white flowers.
  • "Pinkie" lives up to its name 2 ways. It does indeed have pink flowers. It is also a dwarf rosemary, with small leaves.

Good Choices for Rosemary Grown in Pots

  • "Blue Boy" is a small bush rosemary with proportionally small leaves that grow in clusters.
  • "Golden Rain" stays compact and small. Its new foliage has a weeping habit and light yellow markings that darken to green.

Chef Favorites

  • "Miss Jessup", "Tuscan Blue" and "Spice Island" are all excellent choices for cooks. The large plants, growing 4-6 feet in the ground, also have large leaves that are very fragrant and hold their flavor when cooked or dried.

Using Rosemary

Rosemary is a triple threat herb. It's ornamental, it's fragrant, and it's delicious. Both the leaves and the flowers are edible. Simply snip off pieces of the stem as you need it.