- So how cold-hardy is Rosemary?
- Growing Rosemary in your Home Garden
- Growing Perennial Herbs In Your Garden
- History of Rosemary
- Rosemary Seeds or Plants
- Cultivation of Rosemary
- Rosemary Growing Tips
- Pest and Problems for Rosemary
- Harvesting Rosemary
- Popular Varieties
- Winterizing Rosemary Plants – How To Protect Rosemary In Winter
- How to Protect Rosemary in Winter
- Rosemary: The herb with winter problems
So how cold-hardy is Rosemary?
My rosemary looks fine after weeks of 20-degree weather
One of the many mysteries of gardening is the contradictory advice we read, especially but not solely on the Internet, about plants. It can even contradict our own experiences growing plants in our very own gardens, so what’s a gardener to do? I always go with my own experience – and keep an eye out for why mine was different.
Take this rosemary, for example. According to everything I’ve read, it can’t survive freezing temperatures – yet here we are in late January after an unusually wintery December, and this specimen on my deck is just fine, thanks. And don’t tell me that’s because it’s up against the house and therefore in a “sheltered location” because I only moved it here for the photo. Its real location is out at the edge of the deck, fully exposed to the wind.
But I’ll back up and tell you what some online sources I usually find trustworthy are saying about rosemary. Garden writer and horticulturist Marie Iannotti tells us, “The three fundamentals for successfully growing rosemary are: Sun, Good Drainage and Good Air Circulation. Provide a sandy, well draining soil and 6-8 hours of full sunlight. ” Then about winter-hardiness, “If you live in a frost free area, you can grow rosemary in the ground year round. Where the winter temperatures dip below 30 degrees F., rosemary plants will have to spend the winter indoors.” See, as though it can’t take frost! And from Fine Gardening Magazine we learn that: “In the fall, when the temperature dips to 30ºF, it’s time to bring rosemary indoors.”
Source after source repeats this warning that rosemary can’t handle temperatures below 30. So I posed my burning questions to Kerry Kelley, Homestead’s manager of annuals, including herbs, and she replied:
There are a couple of varieties that we know make it in our zone 7. ‘Arp’ rosemary is considered the hardiest. It’s an open, upright plant that should do fine here with proper siting. Also ‘Hardy Hill’, but that’s not as frequently commercially available. Some people with zone 8 microclimates (Capitol Hill, inner city Baltimore, close to the bay, or just a warmer, protected spot) may be able to grow other varieties–some success had been had with ‘Tuscan Blue’.
Also consider that the bottom temperature for zone 7 is 0 degrees and for zone 8 I think it’s 10 degrees. If we have a relatively mild winter, with only sporadic temps below 10, other varieties may last. But when the REAL Maryland winter returns (if it ever does), the plant will be toast. In other words, plants may do fine for a few years, and then we have one hard winter and the fun’s all over! And that’s true of any zone 8 plants, not just rosemary. A warm spot near the house protected from north winds is the best bet. Plants really should be in the ground and not in a container, since roots are not as hardy as top-growth.
I love one of the tips one of my customers gave me about using rosemary: she sprinkles the flowers on her family’s breakfast eggs–beautiful and delicious.
Rosemary flowers sprinkled on eggs – what a wonderful image!
But I’ll end with what everyone seems to agree on: that as a Mediterranean plant, rosemary likes it sunny and dry – which means great drainage, something that pots usually do a good job of providing. And rosemary can be pruned to almost any shape, so it’s popular among enthusiasts of topiary.
Posted by Susan Harris.
Growing Rosemary in your Home Garden
With very little effort and not even the best soil, a gardener can grow enough rosemary to supply not only the needs of family and friends, but every restaurant in the area.
For those who think growing herbs isn’t worth the effort, a quick scan of the price labels at the supermarket may change your mind. One third of an ounce of dried rosemary can cost close to $4. That comes out to $182 a pound!
And if you’re thinking, ‘What am I going to do with all that rosemary?’consider having your butcher butterfly a leg of lamb. Douse it with olive oil, some crushed garlic, black pepper and lots of fresh rosemary. Refrigerate overnight and grill it on a bed of rosemary sprigs. Rosemary also is great with pork, chicken and even potatoes.
Grown from either plants or seeds, rosemary is an outstanding perennial performer in Zones 7 to 10 with reports of it thriving in Zone 6 not uncommon. Plants can be brought indoors to overwinter in colder zones.
If you are unsure of your agricultural zone, simply visit our Growing Zone finder and enter your zip code to find out which zone you reside in & its frost-free date.
Growing Perennial Herbs In Your Garden
History of Rosemary
A member of the mint family, like so many herbs, rosemary’s history is rooted in ancient times. The Greeks and Romans made mention of its medical and mystical properties in addition to more realistic uses in the kitchen. Rosemary found its way into the folklore of many countries where it was thought to ward off evil spirits as well as being a symbol of the fidelity of lovers.
With its attractive spike-adorned stems, rosemary also found its place in Christmas decorations as it is easily added to wreaths and sprays.
Rosemary Seeds or Plants
Although plants are available and useful where just a small amount of rosemary is needed, the only way to make a real statement is to grow rosemary from seed.
A packet contains 100 seeds, and if all germinate, we’re talking about a rosemary hedge that can add year-round color to a fence, serve as a backdrop for flower beds or even take summer grilling to new heights.
Cultivation of Rosemary
Seeds should be started indoors about 10 weeks before a zone’s frost free date. Don’t fret if that date has passed, rosemary is a perennial and given a summer of growth, it will thrive.
Fill a container almost to the top with a good seed starting mixture, sprinkle the seeds on the surface, and then cover with an additional 1/2 inch of the starting mixture. Keep the container evenly moist. The seeds will sprout in 14 to 21 days. When they are a couple of inches tall and the weather has warmed up, harden them off by putting them outside during the day and bringing them in at night for a few days and then plant them outdoors.
Rosemary Growing Tips
Rosemary requires only sunlight, good drainage and ample air circulation to thrive. A sandy, well draining soil and 6 to 8 hours of full sunlight daily will have the plants off and running in no time.
There is little need to fertilize rosemary plants. A basic 5-10-5 fertilizer applied in the spring and perhaps a foliar spray mid season will keep the plants healthy and happy.
Where winters are somewhat severe and sustained temperatures are well below 30 degrees F., rosemary plants will have to be brought indoors for the coldest months.
Grown in a sheltered area with a southern exposure, my plants have survived short periods of temperatures in the low teens.
If low temps persist, bring a few plants indoors. Put rosemary plants in terra-cotta pots and water only as needed to prevent drying out. Rosemary doesn’t need a lot of water whether indoors or out, but it does need to be put in front of a sunny south facing window. If this is not possible, use artificial light. Heat is not critical. A cool room will do fine. Move the plants back outdoors once the frost-free date has passed.
Pest and Problems for Rosemary
Rosemary grown indoors is susceptible to powdery mildew, a fungus that can develop where the air is humid and good circulation is lacking. Counter these conditions by keeping indoor plants and air somewhat dry.
Aphids and spider miters, if present, can be controlled with a spray of insecticidal soap.
Snip off sprigs of rosemary all summer and into the fall and winter as needed. Where winter temperatures are severe and bringing plants inside is not an option, rosemary can be easily dried and stored.
Simply bundle sprigs and hang them inverted in a warm, airy place. A covered porch works fine. Once dried, store the sprigs or stripped off leaves in sealable plastic bags or jars. They will keep until next season’s crop is ready to harvest.
Rosemary is a perennial evergreen shrub in warmer growing zones (zone 8 and above). Plants can grow to 4-6 feet tall with some varieties having a trailing or cascading habit. Foliage is dark green and needle-like much like a spruce or fir. A white band on the underside gives it a gray coloration. In the Midwest, rosemary often does not overwinter successfully and is best treated as a tender perennial, bringing it indoors for the winter. During the summer, rosemary produces small white, pink or blue flowers. The fragrance is an intense camphor or piney scent.
While rosemary can be grown from seed, it is best propagated from stem cuttings. Cuttings root easily and grow into suitable plants quickly. Seed germinates very slowly and the resulting plants may take years to become useable plants.
In the garden, rosemary prefers a full sun location with a soil that is well amended with compost and well-drained. Regular fertilization results in the best foliage for harvest. Because rosemary is not reliably hardy in zone 6 or colder, they are best overwintered indoors. If the plants are to be brought indoors it is suggested that they be planted in containers for outdoor use and not planted in the ground.
Rosemary plants grown in the garden do not transplant very well. So, to minimize chances of losing plants being dug up and moved indoors, it is suggested that they be treated as container plans on the deck, patio or porch. Plants can be left in the garden into the fall and brought in just before a frost occurs.
Once indoors, rosemary prefers a cool (even cold) sunny location where the humidity is high. Rosemary dries out quickly in an indoor growing environment usually leading to brown leaf tips and die-back. This does not mean water the plant more because this can lead to root rots and loss of the plant. Keeping the plants cool and placing them on pebble filled saucers filled with water helps to increase humidity around the plant and reduce foliage damage. Frequent misting is also helpful. Keep the soil on the dry side. Rosemary also does not do a lot of growing during the low light, cool days of winter. Rosemary is also a bold accent or specimen plant in containers. The prostrate forms are attractive in hanging baskets and as ground covers where they are hardy.
The tender tips and foliage can be cut as needed throughout the growing season. Occasionally, longer, woody stems can be harvested and used as skewers for kabobs. Leaves may also be dried and stored for later use. Pruning the plants will encourage a tight compact habit. Plants can also be sheared or pruned into forms resembling small evergreens.
Use rosemary sparingly as an accent to food as the flavor can be somewhat pungent and resinous. Use with fish, pork, lamb, poultry and game.
- ‘Arp’ – Grey-green foliage. One of the more cold-tolerant varieties to perhaps zone 6.
- ‘Gorizia’ – Tall upright form, large leaves, light blue flowers.
- ‘Blue Rain’ – Trailing variety, light blue flowers.
- Pine Rosemary – While not a culinary variety, it is excellent as an ornamental. Strong pine scent, fine leaves.
- ‘Tuscan Blue’ – Upright form, mild flavor.
- ‘Huntington Carpet’ – Trailing form, deep blue foliage.
- Herb Directory
- Preserving Herbs
Winterizing Rosemary Plants – How To Protect Rosemary In Winter
Can rosemary survive outside over winter? The answer depends on your growing zone, as rosemary plants are unlikely to survive temperatures below 10 to 20 F. (-7 to -12 C.). If you live in USDA plant hardiness zones 7 or below, rosemary will only survive if you bring it indoors before the arrival of freezing temperatures. On the other hand, if your growing zone is at least zone 8, you can grow rosemary outdoors year round with protection during the chilly months.
However, there are exceptions, as a few newer rosemary cultivars have been bred to survive temperatures as low as USDA zone 6 with ample winter protection. Ask your local garden center about ‘Arp,’ ‘Athens Blue Spire’ and ‘Madeline Hill.’ Read on to learn about protecting rosemary plants in winter.
How to Protect Rosemary in Winter
Here are some tips for winterizing rosemary plants:
Plant rosemary in a sunny, sheltered location where the plant is protected from harsh winter winds. A warm spot near your house is your best bet.
Prune the plant to about 3 inches after the first frost, then bury the plant entirely with soil or compost.
Pile 4 to 6 inches of mulch such as pine needles, straw, finely chopped mulch or chopped leaves over the plant. (Be sure to remove about half of the mulch in spring.)
Unfortunately, there is no guarantee that your rosemary plant will survive a cold winter, even with protection. However, you can add a bit of extra protection by covering the plant with a frost blanket during cold snaps.
Some gardeners surround rosemary plants with cinderblocks before adding mulch. The blocks provide extra insulation and also help hold the mulch in place.
Rosemary: The herb with winter problems
“There’s Rosemary, that’s for Remembrance.” The herb rosemary is grown each year in many home gardens. It is an attractive, narrow-leaf evergreen shrub. It grows well during the summer in Michigan but has confounded many gardeners on how to keep it alive for the rest of the year. No matter what they try, they cannot get it to stay alive over the winter.
Photo credit: Fir0002/Flagstaffotos
Rosemary (Rosemarinis officinalis) is prized as an herb with a powerful flavor and fragrance. When used in cooking or baking, a little goes a long way when adding flavor. Gardeners often would like to either have it be alive in the spring outdoors or dig up the plant and bring it indoors. But no matter what they try, the plant is dead before the first daffodil blooms.
Why the plant is so difficult to manage goes back to its origins. It thrives in a Mediterranean climate that offers bright, hot sun, sandy, well-draining soils and temperatures that don’t dip much below 30 degrees Fahrenheit. During the winter months, it prefers cooler temperatures of 60 to 65 degrees during the day and 40 to 50 degrees at night. The light needs to still be bright and the air should be damp. Circulating air helps prevent fungal diseases like powdery mildew.
It now becomes abundantly clear why leaving it outside in the garden ends its spicy life. It is considered to be hardy in Zones 7 to 10. That’s climates like North Carolina, Texas and California. A large part of Michigan is rated Zones 4 and 5. That indicates that the winter temperatures could dip to -10 to -30 degrees.
When rosemary is potted up to come indoors to play houseplant, the temperatures that humans seek for winter comfort are too warm for it. Rosemary does not get that cool resting period it requires. It is either over-watered or left to dry out too much between water applications. And Michigan has so much cloud cover during the winter that the plant is often light-deprived.
Those blessed with a minimally heated greenhouse have the best chance of success. The rest of us just buy another in the spring and begin again.
When Shakespeare wrote, “There’s rosemary, that’s for remembrance,” he meant it to refer to the belief that rosemary helped the memory. But now it could be interpreted to mean that by spring, all we can do is remember the plant when it was alive.
- Gardening in Michigan website