Rosemary is a fragrant herb I like to have in my container garden. It’s also one of the hardy plants that don’t need much love and care like some other herbs. But the rosemary might stop growing based on certain conditions.
Your rosemary is not growing because it’s not getting the required sunlight of at least 6 hours full sun every day. It may also not grow if you are giving it too much water as it’s an arid plant. The temperature has to be at least 75 degrees Fahrenheit to grow rosemary.
I’ve written all the possible problems that may cause your rosemary plant to stop growing. And the solutions that can help you fix such issues.
1. The plant does not get sufficient sunlight
The rosemary is a hardy plant that needs full sun to grow well. This means it has to get at least 6-8 hours of sunlight every day.
If your plant is not growing well, the first thing to check is if it gets this required sunlight. Make sure the plant is not obstructed by another plant, wall, or fence.
If you’re growing the rosemary in a container, you can move it to a location that gets the required sunlight. If the plant is growing in a garden, you’ll need to take it out and replant it in a suitable location.
2. You provide too much water
The rosemary plant originates in the Mediterranean region that has dry soil and low to medium nutrients. You need to provide the same environment if you want the rosemary plant in your garden to grow well.
One of the most common mistakes we make is to water the rosemary like we would other plants. But providing good moisture to the rosemary roots will actually stunt its growth.
You should only provide it water when the soil turns dry. The easiest way to know this is to stick your finger 2-4 inches into the soil and check the tip. You should water the plant only if the tip of your finger feels dry.
You should only need to water the rosemary plant every couple of weeks in the summer. You can check the soil every morning as part of your routine inspection of the garden.
When you water the rosemary plant, you want to water it deeply. This means keep watering the soil so it soaks full with the water. Do not water shallow as this will cause the roots to develop shallow and result in poor growth.
If you’re growing the rosemary in a container, you need to water the potting soil till it flows out of the drainage holes at the bottom.
3. Rosemary is not getting the correct soil
Soil is one of the most important factors when growing any plant including rosemary. For most plants, I would suggest a fertile soil that is rich in nutrients and has good texture. This would help the soil retain the required moisture and drain out the excess.
But because rosemary is used to growing in harsh environments, it wants soil that has a good amount of sand in it. So it may be a problem if you’re trying to use loamy soil to grow the rosemary plant. This can affect the plant’s growth.
I would recommend you have soil that contains a decent amount of sand in it. If your garden soil does not have enough sand, you can consider buying some horticultural sand and mixing it in. If you’re growing rosemary in a container, you need to add about 20% horticultural sand to the potting soil when preparing the container.
The sandy soil helps drain the water out faster than regular soil and keep the conditions dry. This is exactly what the rosemary plant needs to grow well.
4. The temperature is too low
Rosemary is a warm-season plant that grows in the hot Mediterranean climate. You need to grow it in a temperature that is at least 75 degrees Fahrenheit while it’s maturing. Once the plant has matured, it is hardy to survive at low temperatures as well.
The plant won’t survive if the temperature goes below 32 degrees Fahrenheit. So you can’t grow this plant in winter with freezing temperatures. If you are growing it in a container, you can bring the plant indoors where it’s warm.
So if your rosemary plant is not growing well, one of the places to look is if the temperature is high enough for the plant to grow well. You can try to use a row cover and heating over the plant to try and keep it warm if that’s the case.
But I would recommend the best time to grow the rosemary plant is during summer when the temperature is high enough so it can grow fast.
5. The space is too small to grow
The rosemary plant can grow wide so you need to allow it at least 2-4 feet distance from other plants. If the plants are too close, they will compete with each other for nutrients and moisture from the soil.
The plants will also block each other causing a lack of sunlight and airflow through the foliage. A lack of air circulation can cause a humid environment that will attract pests and fungal diseases to the rosemary plant.
So check whether your rosemary plant has sufficient space to grow when planted in the garden or a container. If you find that it’s struggling with another plant, take the rosemary out and plant it in another location or a separate container.
A short-term solution is to prune the rosemary and neighboring plants so that at least sunlight and the air is reaching all parts of the plant.
6. You may have a dwarf variety
Sometimes there may be nothing wrong with the rosemary you are growing. It may just be that the plant is a dwarf variety that will only grow a few inches tall.
Such a variety is suitable for growing indoors as part of a kitchen garden. You can grow it in small containers without the need for much potting soil, water, or nutrients.
The only requirement for such a plant will be plenty of light. You need to provide this by keeping the plant near a windowsill. Or using artificial lighting indoors.
The seed packet that you buy from a nursery, garden center, or online store will have the information if it’s such a variety.
7. Providing too much of nutrients
The rosemary plant is a hardy plant that grows well in sandy soil that has low nutrients. You may be treating it as other herbs and providing it with lots of fertilizer.
But that’s a bad thing to do as the rosemary plant will not grow if it’s already getting nutrients from the fertilizer. I would suggest not adding any fertilizer and let the plant grow on its own in the garden getting nutrients from the soil.
The only reason you should add a little bit of fertilizer is if the plant is showing signs of yellowing and dried leaves. And even then you want to use half the amount you would use with any other plant. It’s fine to use a balanced, organic fertilizer that has an N-P-K value of 5-5-5 or 10-10-10.
My favorite way of providing nutrients to herbs is to use organic compost that adds nutrients as well as beneficial organisms to the soil. But you just need to add a little bit of it to the soil where you’re growing the rosemary plant.
8. The rosemary plant is infested with pests
If your rosemary plant has a large infestation of pests, there’s a good chance it won’t grow well. Pests that can affect the plant include aphids, spider mites, whiteflies, and spittlebugs.
Some of these pests will suck the sap out of the foliage and cause them to turn yellow, dry out, and even fall off. This means the plant can produce less food for itself.
I recommend inspecting your rosemary plant every morning as part of your routine. This way you will immediately figure out any pests on the plant as soon as they arrive.
The easiest solution to getting rid of pests like aphids is to spray water on the foliage and dislodge them onto the soil. If there is a large infestation of pests, you can try to spray insecticidal soap or neem oil on the plant.
You can mix 3-5 tablespoons of such soap or oil in a gallon of water and fill it in a spraying can. Then spray the mixture on the rosemary plant every couple of weeks till the pests go away.
9. Your rosemary plant has a disease
If you’re already growing plants in the garden, you know at some point they will be affected by a disease. That’s just how the natural world works.
And the same can happen with your rosemary plant. It can be infected by a fungal, bacterial, or viral disease which will cause its growth to be stunted.
The most common problem in the garden is caused due to overwatering of the plant. Especially a plant such as rosemary that needs less water, to begin with.
The overwatering can cause the build-up of moisture in the soil causing the roots to rot due to a fungal disease. You can avoid this problem by only watering the soil when it’s dry a couple of inches below the soil.
If the root rot has started to set in, you’ll need to remove the rosemary plant and cut the infected roots out. Then plant the rosemary in another location that is free from this problem. If all the roots are infected, you can’t do much except discard the plant.
Another issue is if you splash water on the foliage when watering the plant. This can cause a humid condition causing fungal diseases like powdery mildew. The best thing you can do in this case is to cut off the infected foliage to save the remaining parts of the plant.
The rosemary can suffer bacterial diseases such as blight or crown gall where growth may occur on roots and stem. You can avoid bacterial problems by keeping the plant clean.
When you’re pruning the rosemary, make sure to clean the pruner with rubbing alcohol before using it on the plant. This can help keep bacterial diseases away.
Once the plant is infected by such a disease, the best you can do is to cut off the infected portion. If the infection is over the entire plant, you’ll need to get rid of it.
How do you encourage rosemary to grow
If you find that your rosemary plant is not growing, you can take some steps to encourage its growth. Make sure to cover the basics and plant it in a mixture of 20% sandy and 80% loamy soil.
Reduce the water that you provide to the soil near the plant. Only water the soil when it’s dried 2-4 inches inside the ground. The hardy environment will encourage the rosemary to grow.
Make sure you don’t add fertilizer to the soil when growing rosemary. The plant can gather its nutrients on its own. Not providing additional nutrients will encourage the plant to grow more.
Plant the rosemary in a location that can get at least 6-8 hours of sunlight every day. And make sure you grow the rosemary when the temperature is at least 75 degrees Fahrenheit. These are ideal conditions that will speed up the growth of the plant.
Pruning is one of the best ways to encourage the rosemary plant to grow. You need to trim the leaves and new branches of the plant. Trimming the leaves and branches will encourage the rosemary plant to grow even more of them.
You can use the leaves that you trim as herbs in your cooking. You can use a bypass pruner to trim the foliage. But make sure to clean it with rubbing alcohol before use to avoid spreading the disease to the plant.
You can check the plant every couple of weeks whether it requires some pruning. But only trim 1/3rd of the plant at a time. If you try to cut off more of the plant, it will get stressed.
The plant won’t have enough foliage to produce the required amount of food and this can impact the growth.