We grow most herbs from seeds. But we always grow rosemary from stem cuttings. It is not that difficult to sow rosemary seeds, however, propagating rosemary using fresh cuttings is a much simpler way of growing rosemary.
To successfully propagate rosemary from cuttings is a two step process. First you need to get a stem cutting to develop roots. Next you need to develop the cutting into an new, established rosemary plant. Needless to say are both steps are equally important when you propagate plants.
Often guides focus on how to get the cuttings to root. But that is not even half the battle. The real challenge with rosemary is to keep the young developing plant happy and to end up with a well-established rosemary plant.
Here in this article, we will start by looking at how you can grow rosemary from cuttings. We then highlight 11 common mistakes to avoid to help you in growing your rosemary cuttings into established rosemary plants for you to enjoy for many years to come.
- Growing rosemary plants from stem cuttings
- 5 step Guide to propagating rosemary
- Observe and be prepared to transplant it into a larger pot
- 11 mistakes to avoid caring for a rosemary plant
- 1. Rosemary likes well-draining soil
- 2. Rosemary likes full sun
- 3. Careful with the watering
- 4. When to prune and harvest rosemary
- 5. Correct temperature for Rosemary
- 6. Not enough space for Rosemary to grow and thrive
- 7. Don’t automatically add fertilizer or too many nutrients
- 8. Your rosemary plant is infested with pests or diseases
- 9. Root rot due to overwatering, wrong soil, or pot
- 10. Using the wrong type of pot, container, or location in your garden
- 11. Make arrangements for your rosemary plant to survive winter
Growing rosemary plants from stem cuttings
This part of the process focuses on how to best get root growth from your rosemary cuttings. Rooting rosemary can be tricky but you will find that our method is simple to follow. Before starting, let’s point out two things about propagating rosemary.
- We use potting soil as a growing medium for cuttings when we propagate rosemary. There are gardeners who prefer using water as a medium for cuttings. And it may be easier to develop new roots in water but the transfer from water to soil later can be risky at best. Root development means nothing if the roots do not take to their new medium when you re-pot.
- Avoid using a rooting hormone to stimulate root growth. Often you will have to wait a full year before using herbs in the kitchen if you are using rooting hormone in the rooting process. We prefer organically grown herbs.
It should of course not hurt your chances to root your cuttings if you dip them in rooting hormone before planting. But we do not know for sure as we do not use rooting hormones. We find that rooting rosemary works well without it.
5 step Guide to propagating rosemary
1. Preparation when growing rosemary from cuttings
To propagate rosemary successfully you need:
- An established rosemary mother plant (or cuttings from a plant)
- Well drained potting soil
- A pot with a drain hole made from material that breathes
- 3 long wooden sticks or skewers
- A plastic bag
- A rubber band or some string
You should always plant more rosemary cuttings than you need plants. We have propagated rosemary from cuttings countless times and a 100% success rate is not guaranteed.
If you are new to propagating herbs and want 2 rosemary plants, start with 8 - 10 cuttings. Then the general rules is to double the number of rosemary cuttings to plants required as you most likely end up losing some cuttings in the process.
2. Start with fresh cuttings from a mature rosemary parent plant
Your rosemary cuttings should be at least 15 cm (6 inches) long and fresh but firm rather than wooden.
If you look at an established plant you can divide the branches into 3 separate sections:
- You have branches that are wooden at the base
- The wooden branches turn into semi-wooden branches a bit further along
- And finally further up the stem turn into fresh new growth at the very top
You want your stem cuttings to be from the top third of the branch. But do make sure that the stems are more fresh than wooden for successful propagation.
Use a clean and sterile pair of scissors or a sharp knife to cut the branch just below a pair of leaves. Be gentle as you do not want to hurt a leaf node in the process.
Look at the very tip of your rosemary cuttings. If you can see fresh new growth at the very tip you should cut it off using a pair of sharp scissors. This will encourage the cutting to use its energy to build roots rather than develop new top growth. Cut the top just above a healthy-looking and established pair of leaves.
3. Strip leaves from the bottom half of cuttings
When you have cut your rosemary cuttings you need to prepare them before you plant.
Turn the spring upside down, pinch the stem between two fingers and proceed to strip the leaves from the bottom half of the remaining cutting.
4. Plant in well-drained lean potting soil
Now fill your pot with well-draining and lean potting soil mixed with 30-50% coarse sand or Perlite. I prefer to use Perlite but coarse sand works just as well.
Planting the rosemary cuttings is quite easy. If the cuttings are firm you can simply push them down. Be careful to stop before the lower leaves touch the potting soil. If the cuttings are soft, use a stick or your finger to make a hole for your cuttings.
I prefer to plant one sprig or stem cutting per pot. But you can plant 3-5 rosemary sprigs in a medium-sized pot if you prefer.
When the cuttings are planted you should water them thoroughly. You want the soil to be moist throughout the pot.
5. Build your plastic bag greenhouse
With the cuttings in place, insert your wooden sticks into the soil at the very edge of the pot. The objective is to create a frame to hold and support a plastic bag.
I have found that placing the sticks in the shape of a triangle works best.
Next, make 5-10 small holes in the plastic bag using the tip of a pen or something similar. Then proceed to cover the pot from the top and fasten the bag to the base of the pot using a rubber band or string.
You have now created a mini greenhouse that will give your cuttings a moist and nourishing environment where they can grow and develop.
Observe and be prepared to transplant it into a larger pot
When the cuttings are planted and the mini greenhouse is in place it is time to be patient.
Make sure that your cuttings get direct light and keep them in a room temperature environment. Watch out for too much moisture to build up on the inside of the plastic bag.
If you have planted several cuttings in one and the same pot you will have to transplant the cuttings into new pots as they develop. This will however not be necessary for at least 4-6 weeks as it takes time for the new plants to get established.
And there you have it. If you have made it this far in the process you are almost halfway to growing rosemary plants from your fresh rosemary cuttings.
The main reason for planting 1 stem cutting per pot is to reduce the risk of disturbing the cuttings as they are developing.
But there are still hurdles to cross. Next, we will look at 11 common mistakes when growing and caring for a rosemary plant. Rosemary is in many ways a hardy plant. But still, there are things to observe if you want your plant to be a perennial that indeed does come back every year.
11 mistakes to avoid caring for a rosemary plant
Getting rosemary cuttings to root is an achievement but still only half the battle. Now you need to ensure that you give your developing rosemary plants the best possible care. If you do, this perennial herb will serve you and your kitchen well for many years to come.
Here are 11 mistakes to avoid to help you troubleshoot problems and show how to grow a healthy rosemary plant.
1. Rosemary likes well-draining soil
Rosemary is a Mediterranean perennial herb that is found growing in what we would consider almost hostile conditions.
Poor soil quality, not a lot of water or nutrition can be tolerated as long as the soil drains well.
So if you are only planning on getting one thing right make sure to focus on using well-draining soil. Rosemary will not survive if the roots sit in wet soil. The plant will suffer root rot and it is nearly impossible to bring the plant back to life.
Start with good quality potting soil and then add drain improving material and substances. I also always add drain-improving materials like LECA pellets or coarse sand to the very bottom of my pots.
If you are planting your rosemary outdoors, raised garden beds can help improve drainage.
2. Rosemary likes full sun
And when I say full sun I mean a minimum of 8 hours per day.
Remember, rosemary is a Mediterranean herb and there is very little risk that you would manage to overexpose your plant to direct light.
3. Careful with the watering
Do not overwater your plant. Rosemary prefers a mild dry out to daily and constant watering every time the surface of the soil dries up.
When you do water try to alternate between bottom watering and watering from the top using a spray bottle or a watering can. And when you do water you should water thoroughly.
In the height of summer, I water rosemary pots once a week. And the plants thrive. Constant watering will entice the roots to grow shallow and weaken the root system.
Also, be mindful not to get water on the lower leaves of the plant when you water from the top. Always water at the base of the plant even if it means lifting the branches. Getting water on the foliage increases the risk of fungal diseases like powdery mildew.
4. When to prune and harvest rosemary
Harvest your rosemary plants continuously throughout the growing season. And always harvest from the outside in and do not be afraid to harvest what you need. But never more than 1/3 of the plant in one go.
Continuous harvesting and pruning will encourage the rosemary plant to produce more new growth.
Simply cut off the sprigs you need and watch your plant thank you by producing even more delicious leaves.
Rosemary likes to be pruned early spring and throughout the growing season. But do not prune your plant as you move it indoors for winter. If you prune new growth you will stimulate the plant to focus its energy on producing more new growth. Instead let your plant rest and use its energy to stay healthy and grow strong for the next growing season.
5. Correct temperature for Rosemary
Rosemary is a Mediterranean herb and wants to grow in hot climates.
Your rosemary plant needs a minimum of 20 degrees Celsius (70 F) while it is developing. An established plant is hardy and will tolerate lower temperatures but you should avoid exposing your rosemary plant to cold temperatures.
6. Not enough space for Rosemary to grow and thrive
A rosemary plant will grow to become large and need at least 60 cm (2 feet) between plants. This also means that you should only grow one plant per pot or container.
Do not cram your new plants together.
Giving your new rosemary plants enough space will also ensure good air circulation. Good air flow is essential to avoid creating a moist and humid growing environment that can attract fungal diseases and pests.
7. Don’t automatically add fertilizer or too many nutrients
As gardeners, we want the best for our herbs. And this often means using fertile soil rich in nutrients and organic matter. But when you grow rosemary plants you need to think differently.
A few weeks into the growing season it may feel like it is time to give your rosemary a boost of fertilizer.
Do not assume your rosemary plant needs fertilizer or additional compost. Rosemary plants rarely need more nutrients than they can extract from the soil they are planted in.
Rosemary is a herb that is used to grow in almost hostile environments and adding too much fertilizer can hurt the growth and wellbeing of your plant.
If you are convinced that your rosemary bush needs a boost, start by using a general purpose fertiliser (NPK 10-10-10) and dilute it to a third of its recommended dosage. Observe how the plant reacts before deciding how to proceed.
8. Your rosemary plant is infested with pests or diseases
Rosemary is a hardy plant and is known for being disease resistant. But rosemary plants are by no means immune to pests and disease.
Pests and diseases include aphids, spittlebugs, whiteflies, powdery mildew as well as root and crown rot.
The damage from pests and diseases is often visible with tell-tale signs of yellow, black, and even dying leaves.
Some pests can be sprayed off using a hose as the rosemary plant is hardy. Some can be shaken off or removed by hand.
If you have a plant that is badly infested it may be wiser to simply destroy the plant to protect your other herbs.
If you use your herbs for cooking you need to be careful about the type of pesticide you use. My choice is Neem oil but be careful not to treat your plants when they are exposed to direct sunlight. And remember, the best protection is prevention so inspect your plants on a daily basis.
9. Root rot due to overwatering, wrong soil, or pot
When leaves turn yellow and there are no signs of pests and infestation it is easy to reach for the watering hose.
This could however be a mistake as yellow leaves could be the telltale sign of root rot due to overwatering.
Root rot is unfortunately often irreversible. When leaves turn yellow the mold has by then spread throughout the root system.
As with many problems involving pests and diseases, prevention is your best defense. Use well-draining soil and do not overwater your rosemary plant.
10. Using the wrong type of pot, container, or location in your garden
Rosemary does not like the roots to sit in wet soil.
It is key to use well-draining soil and to water sensibly. But you should also ensure that you grow your plant in an ideal growing environment.
You want a growing environment that drains well and if you use a pot it should be made from a material that breathes.
You have several good options:
- use a terracotta pot with drain holes
- buy or make your own grow bags from breathable material
- plant your rosemary plant in a raised bed
The key is to create a growing environment that allows the roots to breathe.
Avoid using plastic pots or containers from composite materials that do not breathe.
11. Make arrangements for your rosemary plant to survive winter
Rosemary does not like freezing cold temperatures. This is one of the main reasons why we find it easier to grow rosemary in pots, containers or grow bags that are easy to move around for the best-growing conditions year-round.
When winter is approaching you should make arrangements to protect your plant.
If you are growing outdoors, cut back your plant and cover it with several inches (5-10) of straw or mulch. Placing wooden boards or stones around your plant is another way to protect the plant and at the same time keep the mulch in one and the same place.
If you can, move your plants indoors. I have had the most success when placing the plants in our unheated conservatory. I place the pots next to a glass panel with lots of natural light. If we have freezing temperatures outdoors I insulate the pot with bubble wrap or sheets of newspaper and make sure to lift the pots off the ground using blocks of wood.
I rarely water the plant over winter as the plant is dormant. But I would water sparingly should the soil shows signs of drying out.
Useful resources: University of California