How to Grow Rosemary
Rosemary is an evergreen, fragrant, and delicious herb, and its botanical name is Rosmarinus officinalis. It’s native to the Mediterranean and is used in cooking, for making body perfumes, and for its health benefits as well.
This perennial (completes its lifecycle in 3 or more years) herb occurs in the USDA Hardiness Zones 8 and warmer. It can also be grown as an annual (completes its lifecycle in 1 year). It can be planted in the garden and, depending upon the variety, can become up to 4 to 6 feet in height and can spread up to 4 feet wide. Anyone would wish to grow this pretty-looking, sweet-scented, and useful herb.
Updated: October 11, 2023.
Rosemary is not very difficult to grow, and once it’s well-rooted, it will keep thriving for years. If gardeners in the colder zones wish to grow rosemary, they can grow it in containers so that they can bring the containers indoors during winter to help it survive.
There are several varieties of rosemary, each having slightly different properties. Some of the varieties grow very tall and bushy, whereas others may trail. Flower colors and leaf sizes and shapes also may vary. Some have blue or purple flowers, while others may have white flowers.
Standard rosemary grows up to around 2 meters (6 feet) tall. However, it reaches this height very slowly. The dwarf variety attains a height of around 45cm (18”). This is suitable for container growing.
Obtaining Rosemary Plants
Rosemary can be grown from cuttings as well as from seeds. Also, a small plant or seedling can be bought from a nursery if the grower doesn’t wish to propagate a cutting.
However, growing it from cuttings is the easiest method. Although seeds of rosemary are easily available and typically cheap, their germination rate is generally only around 15%, and seeds take a long time to germinate and grow.
A grower can get a cutting from a friend who has rosemary plants in their garden or from a community garden by asking for a cutting there. If the grower wishes to grow a variety that is not very common or doesn’t occur at all in their area, a cutting can be ordered online, or the help of a local nursery can be sought to get one.
A 3-inch piece from a rosemary plant should be clipped off to propagate. This is best done in the late spring; however, if the climate is warmer, this can also be done during early autumn. The plants grown from cuttings will have the same properties as that of the original plant.
Leaves on the lower section (around 1 ½ inches from the end) of the stem of the cutting should be stripped off. This is very important because if these leaves are left on the stem, they will make the stem rot instead of growing.
Rosemary (Rosmarinus officinalis) prefers soil with a pH range of 6.0 to 7.5. This means it thrives in soils that are slightly acidic to slightly alkaline.
However, rosemary is relatively tolerant and can grow outside this range as well. If you're planting rosemary in a garden or pot, it's a good idea to test the soil's pH first and then adjust it if necessary.
Proper soil pH can help the plant absorb essential nutrients effectively. In addition to pH, ensuring well-draining soil is crucial for rosemary, as it dislikes sitting in waterlogged conditions.
While preparing the soil for planting rosemary, all rocks, weeds, shrubs, plant debris, and tree roots should be removed from the soil. If the rosemary is grown in a pot or container, use good potting soil that drains well.
If required, the soil should be fertilized depending on the test results to provide nutrition from organic matter or compost. If the pH is too low, lime should be added to make the soil more alkaline.
Also, if the soil is too alkaline, one may add some sulfur.
Note: it takes a long time for sulfur to decrease the pH, up to 6-12 months), but it is safer for plants than Ammonium Sulfate or Iron Sulfate.
The surface should be added with around 4 inches of compost or organic matter, which then should be incorporated with a rototiller or a pitchfork to a depth of 6-8 inches. Slightly mounded or raised beds provide the best drainage for rosemary plants.
If your garden has heavy clay, amend it by adding plenty of compost, worm casting, aged manure, some sand, and similar. This will help the soil to drain better, it will help with aeration, etc.
If the soil is really hard to work with, grow your rosemary plants in pots and containers while trying to amend the soil over longer period of time.
After the bottom leaves are stripped off, each cutting should be placed in a small pot filled with one-third of peat moss and two-thirds of coarse sand. The pot should be placed in a sunny spot, but sunlight shouldn’t directly fall on the plant. The temperature should be between 60° and 70°F.
The planted cuttings should be placed in a warm spot until they develop roots and should be watered regularly. Roots develop in around three weeks. In around 8 weeks, the plants become well-rooted and are ready for transplanting to their permanent location.
To help the cuttings grow vigorously, the entire pot should be covered with a plastic bag with a few holes punctured on its top. Due to this, the temperature will be regulated, and the air around the plant will be kept moist and warm.
Also, the tips of the cuttings can be dipped in rooting powder to give them a head start.
Planting Rosemary Plant
Once the roots are developed, the rosemary can be planted either in containers or outdoors. Rosemary is a wonderful plant that adapts to most growing conditions and is pretty hardy. It has no problem with limestone, snow, seaside, high temperatures, and any kind of soil. However, it grows to its best in a warm to hot and fairly dry climate.
The grower should first decide whether they want to grow rosemary in pots or as a shrub in the garden. Rosemary can even be trained as a pleasantly scented hedge. If the climate is cool, containers may be the best option because they can be brought in if required.
For planting in the garden, the cutting should be potted once so as to help it develop more roots and gain vigor before being planted outside. Then, soil should be chosen that drains well. If the soil is waterlogged, there can be root rot. The more alkaline the soil, the more fragrant the plant will become.
Thus, if the soil is too acidic, some lime should be dug in. The preferred soil pH is between 6.0 and 7.0.
Rosemary grows best in full sun. It should receive sun at least for 6 hours every day. But it can also live in part shade as long as the soil is well-drained. If the grower plans to use rosemary as a perennial plant, the site for planting should not be disturbed by tilling.
What if Rosemary Plant is to be Transplanted into Bigger Pots?
Sometimes rosemary grows very nicely in a pot and once it’s transplanted to a bigger pot, it dies. In that case, the root ball might have been disturbed during transplantation, or the transplantation might have been done during its actively growing cycle.
Evergreens like rosemary stay green year-round but grow slowly during winter. Thus, this is the ideal and safest time for transplantation.
When transplanting rosemary, try to dig the plant out with as large a root ball as possible. A new pot or container should be filled with potting soil rich in organic matter. Also, it should drain well.
The new pot should also have enough drainage holes to prevent root issues.
Add enough soil to fill the gaps and holes and press firmly. If it looks like you added too much soil, it is OK - over time, soil level will settle usually ~1 inch (2.5 cm) down.
Feel free to add some decorative pebbles or some sort of mulch - although rosemary grows as an evergreen shrub and protects the soil from strong sun and wind, it is good to protect the soil surface.
Water generously newly transplanted rosemary and let all the water drain away. Place rosemary in a semi-shade position for 2-3 weeks, after which it can be moved to direct sunlight.
Taking Care of Rosemary
Since rosemary loves drier soil more, watering should not be overdone. It will love average garden watering. It’s happy to source most of its water from rain. Sometimes it may be tough to decide when a rosemary plant requires water since its needles don’t wilt like broad leaves.
But on average, rosemary should be watered every 1 to 2 weeks, according to the climate and plant size.
If a grower’s rosemary dries up even after keeping water, the sand might be too heavy. Compost soil should be used in this case. It’s very soft and nutritious for rosemary.
No Need for Fertilizers
Rosemary is an herb that doesn’t need fertilizers. However, it should be ensured the soil contains some lime. If growth is slow or stunted or the plants look pale yellow, organic fertilizer should be applied in early spring before the emergence of new growth.
Any all-purpose fertilizer in liquid or dry form can work well as long as it’s used correctly. Avoid applying fertilizer straight on the plant to prevent leaf burn.
Generally, add some compost or worm casting every late winter to the topsoil, work it into the ground a little bit and your rosemary plants will have all the nutrients they need.
Keeping the Containers Indoors in Winter
If the grower lives in a cold area, they should plant rosemary in containers and bring the containers indoors in winter. In very cold weather (0°F or less), branches of rosemary can get damaged if laden with heavy snow.
If the winter lows in the grower’s area don’t drop down to 0°F, they don’t need to bring the plant indoors.
Rosemary plant doesn’t require pruning for its health. However, the plants grow quite big and occupy a lot of garden space. Therefore a few inches of the branches should be cut back in every spring to give them a nice, manageable shape.
Rosemary is a wonderful plant also because it’s resistant to most pests. Still, if scales, mealy bugs, spittlebugs, aphids, whiteflies, or spider mites appear, any organic insecticides or insecticidal soap should be used.
Scales are sedentary insects, so the best solution for them is to clip off and remove the infested plant tips.
For mealy bugs, the plants should be sprayed with pyrethrum soap, water, or a soap-based insecticide.
Sap-sucking insects are usually more prevalent in areas where excessive nitrogen fertilizer is applied. Most insect problems can be avoided with proper fertilizing.
Rosemary is a wonderful plant also because it’s resistant to most diseases. However, some cases of powdery mildew have been reported. The plants should be checked regularly, and proper fungicides should be applied as needed to prevent the disease from spreading.
Pruning overgrown plants also helps reduce the incidence of diseases as it improves air circulation. Pruning also induces the production of new shoots.
Do Coffee Grounds Help Rosemary to Grow?
Coffee grounds have been a popular DIY addition to garden soils and composts for many gardeners, primarily because of their organic matter content and the nutrients they can offer. However, the effect of coffee grounds on specific plants, including rosemary, is a subject of some debate.
- Soil Acidity: Fresh coffee grounds are acidic, but most of the acidity is removed during brewing, leaving used coffee grounds with a pH close to neutral. However, some sources suggest that over time, as coffee grounds break down, they can slightly acidify the soil. Rosemary prefers slightly acidic to slightly alkaline soil (pH of 6.0 to 7.5), so if your soil is already on the alkaline side, a bit of acidity from coffee grounds might help. But if your soil is already acidic, you'd want to be cautious.
- Nitrogen Source: Coffee grounds are rich in nitrogen, an essential nutrient for plant growth. When mixed into the soil or compost, they can help improve its fertility over time. However, when coffee grounds decompose, they might temporarily lock up some of the nitrogen, making it unavailable to plants. This is often why it's recommended to compost coffee grounds first before adding them to the soil. Rosemary is not a heavy feeder and it doesn't need nitrogen like some other plants, so this should not be a problem, at least not a large one.
- Improved Soil Structure: Coffee grounds can help improve soil structure, especially in clayey soils, by increasing drainage and aeration. Rosemary thrives in well-draining soils, so this aspect can be beneficial.
- Pest Deterrence: Some gardeners believe that coffee grounds can deter pests like slugs and snails. While rosemary isn't typically their first choice for munching, having fewer pests around is always a bonus.
- Potential Concerns: Over-relying on coffee grounds can lead to an accumulation of certain minerals like calcium and potassium in the soil, which might hinder plant growth in the long run. Additionally, coffee grounds can foster the growth of some molds and fungi if they remain moist, which might not be suitable for all plants.
Although coffee grounds can offer some benefits to the soil, it's essential to use them judiciously and in moderation. If you decide to use coffee grounds for your rosemary, consider mixing them with other organic materials like compost or worm castings rather than applying them directly and thickly around the plant.
Or use them for making homemade organic compost.
Can Rosemary Survive Winter?
Rosemary can survive winter, but its hardiness largely depends on the specific variety of rosemary and the conditions of the winter season. Here's what you need to know:
- Hardiness Zones: Rosemary is typically hardy in USDA zones 7 to 10. This means that in zones 7 and above, rosemary can usually survive outdoors all year round. However, in areas with colder winters (zones 6 and below), rosemary is more susceptible to winter kill.
- Varieties: There are various cultivars of rosemary, and some are more cold-hardy than others. For example, the cultivar 'Arp' is known for its cold tolerance and might survive in zone 6 or even zone 5 with proper protection.
- Winter Protection: If you're growing rosemary in a zone where winters are on the edge of its hardiness range, consider these protective measures:
Mulching: Mulch around the base of the plant with straw or leaves to protect the roots from freezing temperatures.
Wind Protection: Rosemary is particularly sensitive to cold winds. Planting it in a sheltered location or using a burlap screen can help shield the plant.
Container Growing: If you grow rosemary in containers, you have the flexibility to move the plant indoors or to a sheltered location during extreme cold spells.
- Indoor Overwintering: For those living in very cold climates, rosemary can be grown in containers and brought indoors during the winter. When overwintering rosemary inside, make sure it's placed in a location with plenty of sunlight (like a south-facing window) and ensure good air circulation. Be cautious about overwatering, as indoor rosemary doesn't need as much water in winter.
- Winter Moisture: While rosemary is drought-tolerant during the growing season, winter is a different story. The combination of cold and wet conditions, especially in heavy or poorly draining soils, can lead to root rot, a common reason rosemary plants die in the winter.
Although rosemary can survive winter in many areas, it requires proper care and sometimes protection in colder zones. By understanding your local climate and taking a few preventive measures, you can help your rosemary plants thrive year-round.
What is the lowest temperature rosemary can survive?
Rosemary is generally hardy in USDA zones 7 to 10. In these zones, the minimum winter temperatures can range from 0°F to 20°F (-18°C to -6°C).
However, it's important to note that these are average low temperatures, and there can be occasional fluctuations.
In the mildest parts of zone 7, temperatures typically don't drop below 0°F (-18°C).
But, there are more cold-hardy cultivars of rosemary, such as 'Arp' and 'Madeline Hill,' which have been known to survive temperatures slightly colder than this, potentially extending into zone 6 conditions. In zone 6, the average minimum winter temperature can drop down to -10°F (-23°C).
That said, survivability doesn't just depend on temperature alone. Other factors, such as soil moisture, wind exposure, snow cover, and the duration of cold spells, can also influence whether a rosemary plant can endure winter conditions.
For instance, a rosemary plant in well-draining soil with protective snow cover might fare better in colder temperatures than one exposed to wet, cold conditions without protection.
Rosemary plants are often grown as decorative plants but also for their aromatic leaves.
When to Harvest
Rosemary can be harvested as soon as it has enough foliage to maintain growth. For plants grown from seed or young cuttings, it may be best to wait until the second year to begin consistent harvesting, ensuring that the plant is well-established.
That said, light harvesting in the first year can be done once the plant is actively growing and has a robust set of leaves. In temperate climates, rosemary can be harvested year-round. However, it's advisable to avoid heavy harvesting during the winter months when the plant is not actively growing, as this can weaken the plant.
How to Harvest
To harvest rosemary, use sharp, clean scissors or pruning shears to cut stems.
It's generally recommended not to remove more than one-third of the plant at a time to ensure it continues to thrive. Make your cuts just above a set of two leaves; this will encourage the plant to branch out and produce more foliage.
Proper harvesting techniques not only provide you with fresh rosemary for culinary or medicinal purposes but also help in shaping the plant and promoting bushier growth.
What is Harvested
When harvesting rosemary, it's the needle-like leaves that are primarily sought after, though the stems can also be used for flavoring in stews and soups.
Fresh rosemary has a more intense flavor compared to dried rosemary, so you'll typically use less of it in recipes. If you want to dry the harvested rosemary, hang the sprigs in a dry, well-ventilated place away from direct sunlight. Once dried, remove the leaves from the stems and store them in an airtight container.
In addition to culinary uses, rosemary is often harvested for its aromatic properties. The fresh sprigs can be added to floral arrangements or bundled together to create fragrant sachets. It is also popular in the production of essential oils due to its distinct scent and potential health benefits.
When harvesting rosemary, it is also vital to ensure good air circulation, to help fight pests and diseases - rosemary is a resilient plant, but better safe than sorry...
Rosemary is wonderful also because it can complement sweet as well as savory dishes. It can be used to add depth to chicken, meat, butter, bread, and even ice cream.
Delicious recipes like rosemary syrup, marinated pork, herb bread, and rosemary-lemon sorbet can be made with rosemary. There is no need to dry rosemary to use it in cooking and eating. A fresh twig can also be added to dishes.
Rosemary tea can also be made with fresh or dried rosemary, around one sprig per cup. It should be steeped moderately because steeping for longer can result in a stronger aroma and bitterness.
Rosemary can even be used around the house. It can be dried, and a scented drawer sachet can be formed from it.
It can also be used in homemade soap and added to bathing water to make it fragrant and to make the user’s hair soft and shiny. The grower can even just brush against their rosemary plant to enjoy a fresh burst of its heartening fragrance.
The simple process of growing rosemary is worth enjoying.
Growing Rosemary Frequently Asked Questions (FAQ)
Although rosemaries are easy to grow, there are some questions that get asked rather often.
Is rosemary easy to grow?
Yes, it is. Rosemary is not very picky regarding soil, it doesn't need much water, it can survive rather cold weather, etc. But, if possible, give it plenty of sun.
Where does rosemary grow best?
Rosemary grows best in sunny locations, with a soil pH between 6.0 and 7.5. It doesn't like "wet feet", so be sure that the drainage is good.
What is the trick to growing rosemary? What is the secret to growing rosemary?
No, there are no secrets or tricks regarding growing rosemaries. If unsure what to do, read this article again and take notes.
Is it better to grow rosemary inside or outside?
Rosemary is a hardy and tough plant that grows well outdoors. But it can grow well indoors as well, just be sure to provide it with plenty of sun or some artificial lighting.
Does rosemary come back every year?
Rosemary plant is an evergreen plant that is green and slowly growing even in winter.
Can I cut rosemary back to the ground?
No, rosemary plants should not be cut to the ground. Some rosemary plants may recover even after such damage, but no, they should not be cut to the ground.