How to Grow Rosemary

Days to germination: Not usually started by seed
Days to harvest: Between 3 months to more than year (depending on how you start your plants)
Light requirements: Full Sun
Water requirements: Occasional watering
Soil: Well-drained, loose and light
Container: Definitely

Introduction

It’s a fairly hardy plant but does not tolerate the cold at all. You won’t be able to grow any rosemary outdoors if your winters get below freezing. That means, you have to be living in an area at least zone 8 or warmer. But it thrives well indoors so a windowsill pot of rosemary is still an option for everyone else farther north.

Though sensitive to cold, rosemary does fine in drought and is a popular herb in dry regions.

Rosemary has thin leaves, more similar to pine needles than the usual leafy herbs. It’s used in many dishes, though particularly popular with roast meats such as lamb or pork. There really isn’t much to rosemary in terms of nutrition. It’s all about the flavor for this herb.

Starting from Seed

Rosemary is a very slow growing plant that also doesn’t germinate all that well in the first place. If you start your plants from seed, you will probably have a year or more to wait before the plant gets large enough to get a decent harvest. The more common way to start rosemary is with small but established plants (usually larger than seedlings).

If you don’t want to pay for a plant, you can compromise by starting with a cutting. Take a cutting that is about 2 to 3 inches long, and trim away the leaves on the bottom inch of stem. Dip the cut end into a small pot of damp potting mix (use rooting hormone for better results). Keep the soil moist, and your cuttings should start to put our roots in about a week. Let them grow indoors for at least another 3 to 4 weeks before putting them outside.

Transplanting

You’ll need a sunny spot that has loose or even sandy soil for your rosemary plants. Rosemary will grow fairly large and bushy, so allow for at least 2 feet between each plant. Healthy plants can grow to more than 5 feet tall in good conditions, so pick your location accordingly or you might start to shade out other plants.

Dig your soil thoroughly to loosen, and make sure the hole is large enough to hold the roots of your plants or seedlings. The roots are somewhat delicate and you can damage the plant if you bend up the roots to fit the hole. Early spring is the best time to be transplanting rosemary.

Growing Instructions

Rosemary is a light-feeding plant and will grow wonderfully without any additional nutrients or fertilizer. Do not over-water your plants though. You should only need to manually water rosemary during a long period of drought. They will grow well in dry conditions, so let them be.

Pinch off the tips of each branch to force the plant to produce more leaves and branches. A bushy plant is more productive than one that grows tall and thin.

It will grow into a sizable bush over time, and a bit of regular pruning (besides your harvesting) can keep it manageable and thriving. Thick or woody stems can be cut away each year after your plant has bloomed for the year.

Containers

For anyone living above zone 7, you’ll have to keep your rosemary indoors over the winter. Thankfully, it does extremely well in containers.

With pruning and frequent harvest, you can keep the size of your plants down. If left untended, rosemary can grow to several feet in height which may not be ideal for your windowsill. You can easily keep it to between 1 and 2 feet with some snipping.

Even with a well-pruned plant, you need a big pot. Containers for rosemary need to be at least 12 inches across and the same in depth. If you have your plant for many years, you may have to re-pot it into something larger. Add extra gravel to the bottom to keep the drainage going. Rosemary will not grow well if it has water-logged roots.

Pests and Diseases

Rosemary can be quite susceptible to powdery mildew, which thrives in moist areas. Keep your plants well separated and don’t douse the leaves when you are watering. You can also clip out the inner branches of the plant to help with air circulation.

The mildew looks like a white dusting on the leaves, and it usually doesn’t kill the plants but it will make your rosemary leaves inedible.

There is one insect that is particular to rosemary, and that is the rosemary leaf beetle. It’s a round little beetle with a metallic green shell. They can do significant damage to the leaves of your rosemary, so pick them off as soon as you find them. If you check your plants daily, you should be able to control the beetle population without resorting to pesticide sprays.

If you do need to spray your plants, make sure to use an insecticide that is approved for use on edible plants.

Harvest and Storage

How long it takes to get a harvest from rosemary really depends on the way you started your plants. If you have started seeds, you will likely have to wait until half way through their second season before you can safely start pruning off leaves. Mature plants can be harvested once they have gotten established in your garden, usually within a month. For smaller seedlings, you should give them at least one growing season (summer) to grow before you start to harvest.

You just have to snip off sprigs of the plant to use. Short sprigs at the tips will be tender enough to use whole. If you take a larger piece (longer than 6 inches), the stem might be a bit woody. You can just trim off the leaves in that case.

For storage, you can freeze whole sprigs or dry them. Frozen rosemary holds its taste better, but will be limp and soft when thawed. More decorative garnishes should use dried rosemary sprigs or leaves.

2 Responses to “How to Grow Rosemary”

Karin Siemens Says:
March 10th, 2011 at 1:13 pm
Two of our three good sized rosemary plants’ leaves are turning yellow. Are they getting too much or too little water. The third is thriving … green and lush looking!

Thanks for your help!

KDS
Rosemary W. Says:
May 14th, 2012 at 5:09 pm
Here in South California we don’t have to worry about Rosemary surviving the winter. Because it does not demand too much water, and we are subject to water use restrictions, we let it grow fairly large and have a lot of area that is covered by it. When I want to cook with it, I can just walk out into the garden and grab some. Once when we had a group of friends over for a backyard barbecue, I noticed one guy taking advantage of it by picking a fresh sprig to flavor his hamburger.