Your rosemary plant may be dying because of an environmental factor that is causing it stress and taking a toll on its overall health.
The most common causes of death in rosemary plants are too much water, lack of sunlight, high humidity and disease.
The first step in saving your dying rosemary plant is correctly identifying the stressor and dealing with it directly. The sooner you identify the cause, the higher the chance of the rosemary making a full recovery.
In this article, we will discuss the different reasons your rosemary plant may be dying and how to save it.
Why is my rosemary plant dying?
Overwatering
One of the most common reasons for rosemary plants to die is because of overwatering. The first signs most people notice are the leaves turning brown or black.
Rosemary is easily affected by overwatering, which is why it needs to be planted in soil that is well-draining and sandy, or even stony.
Being prone to overwatering is also the reason that rosemary is notoriously difficult to grow in pots. It may do fine in pots during the summer because the hot weather dries out the soil faster, but even slight overwatering can suffocate the plant in winter.
These plants like moderately moist conditions, but the key is to have soil that drains well. If you think your potted rosemary is overwatered, you can salvage it by transplanting it to a sunny garden with well-draining soil. If you do keep it in a pot, make sure the pot has sufficient drainage holes at the bottom to effectively get rid of any excess water. Water the plant less frequently than you would if it was in the ground.
Giving the plant time to dry out between waterings is another must. Only water it when the top one or two inches of soil are dry to the touch. When watering, try not to water from overhead, because this encourages the growth of mildew and other fungi.
Insufficient light
The rosemary plant is native to countries in the Mediterranean, which means it likes plenty of sunlight and warm weather. It needs six to eight hours of full sun a day, so it does best when planted outdoors. Make sure it does not get blocked by trees or other plants so that it can get all the sun it needs every day.
If you take your outdoor rosemary indoors for winter, it will end up only getting four to six hours of low light a day, and the plant will have a hard time surviving. The weak light is not enough to produce the energy it needs to stay alive.
The best way to acclimatize your outdoor rosemary to the indoors is by gradually getting it used to less and less light. Before taking it in for the winter, try moving the plant to a shadier outdoor spot for a few days. Eventually, you can move the plant indoors, but make sure the spot you choose is a south-facing window where the plant will still be able to get sufficient light.
Winter
As mentioned above, rosemary likes to be planted in a sunny location and does not do well in the cold.
It is imperative to bring the plant indoors for winter before the first frost. If it is left out in the winter cold, the plant will become pale, brittle and dry, and it will turn yellow or brown.
Light winter can kill several branches on the rosemary plant, but a severe winter will kill the entire plant and its roots.
To help your rosemary survive winters, plant it in a sheltered spot that gets plenty of sun. If there is frost damage, cut off the affected foliage. Do not do the cutting during the winter because the exposed areas will make the plant even more susceptible to frost damage. Do the pruning during the spring when the weather is warmer and conducive to new growth.
Disease
One of the most common fungal diseases that attacks rosemary plants is powdery mildew. Powdery mildew presents as powdery white spots on the entire plant. It grows on rosemary when the plant is in partial shade, because the mildew likes cooler conditions. In a severe powdery mildew infection the plant will shed its leaves.
Give the plant full sunlight and make sure to spray it with water to wash off the white spores and minimize the mildew.
You can control fungal infections by applying a mixture of water and baking soda to the plant. Refrain from using just any fungicide, because rosemary is a herb that is grown for consumption.
High humidity and root rot
High humidity combined with overwatering can result in the plant shedding its foliage and wilting. The plant will turn brown and become brittle. These symptoms are all because of root rot due to the poorly-draining soil and high humidity your plant may be subjected to.
If you notice these symptoms, stop watering your plant immediately and keep it away from rain. Letting the plant dry out is your top priority.
Rosemary prefers dry conditions. Being kept in a location where it can get full sun and good air circulation can also help keep pests away. If there is not a lot of wind where you are, letting a fan blow on the plant a few hours a day can also work. The full sun helps the water in the soil evaporate faster, thus reducing the chances of root rot and other diseases.
If you live in an area where humidity may tend to be a little high, the best way to work around this is simply to give the rosemary plenty of sun and air circulation.
Nutritional issues
Both an excess of, and a lack of, essential nutrients can cause a decline in the rosemary’s health.
In its natural habitat, rosemary grows in nutrient-poor, sandy soil. If you grow your rosemary in garden soil that is already nutrient-rich and add fertilizer on top of that, the high levels of nitrogen may do your plant more harm than good. The roots will burn and the leaves will turn yellow or brown. Too much nitrogen also causes the foliage to grow faster, which will affect the flowers.
If you suspect that you have been overfertilizing, you can try to wash out the nutrients by flushing the soil with water. Just make sure the soil is well-draining and aerated so that it can dry relatively quickly.
Even if rosemary does not need a lot of nutrients, it is still possible for it to need some fertilizer, though incrementally. If your plant is starting to look pale yellow, you might need to fertilize it.
Conclusion
A dying rosemary plant is stressed due to an environmental factor that you need to identify in order to save it from dying.
The most common causes of a dying rosemary plant are overwatering, insufficient light, winter weather, disease, high humidity and nutritional issues.
Save your dying rosemary plant by making sure it has well-draining soil and six to eight hours of sunlight a day. To avoid root rot and other diseases, do not overwater your plant and place it in a well-ventilated area. Bring the plant indoors during the winter as it cannot tolerate the cold.
Rosemary can live over ten years, as long as you provide it with good air circulation, good drainage and plenty of sun.
Image: istockphoto.com / BreakingTheWalls