Rosemary is an evergreen, tender herb mostly found in relatively warm and sunny climates. The plant thrives both indoors and outdoors as long as the growing conditions are right. Unfortunately, Rosemary plants are prone to some diseases and pests that can lead to death. So, if you discover your plant dying, there can be a list of potential causes you need to examine to save it.
So, what are some of the common causes of rosemary plant dying? The most common cause of Rosemary plant death is underwatering or overwatering. Although these plants require consistent watering to thrive, too much or too little water can be just as deadly. Ensure the potting mix is not overly saturated for long periods, and the soil is allowed to dry out between watering sessions. Other causes of rosemary plant dying include inadequate light, the soil being too acidic, extreme winter, high humidity, over-fertilization/lack of fertilization, excessive pruning, and nutrient imbalance.
This blog post discusses the common causes of rosemary plant dying and what you can do to protect it from premature death. Read on to learn more.
Reason #1: Lack of Enough Sunlight
As mentioned above, rosemary prefers warm and sunny climates to thrive. The herb is native to the Mediterranean region that receives lots of direct sunlight and heat. Therefore, the herb is generally heat-tolerant and can survive in full sun.
Rosemary requires 10-12 hours of direct sunlight daily, but it can still survive with eight to six hours of full sun. If you have the herb in your outdoor garden, ensure other plants do not cover it. It must be positioned in an open spot that receives plenty of full sun every day.
If you grow the herb outdoors and prefer bringing it indoors for winter, ensure you provide it with at least six hours of strong light daily. Taking it from 10-12 hours of direct sunlight to four or five hours of indirect, low light can be catastrophic.
If you must bring the herb indoors for winter, help it adjust or acclimate to its new environment. The process must be gradual and done over a few weeks. Otherwise, your Rosemary plant may die.
Place it near a south-facing window, or use grow lights to ensure it receives adequate light for its growth and survival.
If you notice your plant has started to yellow, wilt, and drop leaves, it is an indication of inadequate sunlight. Move it closer to the window or add more artificial lighting.
Reason #2: Overwatering
Overwatering your rosemary plant can lead to irreversible damage. The rosemary plant is naturally drought-resistant and prefers dryer conditions to thrive. Too much watering usually creates damp conditions, promoting root rot. This can, in turn, lead to death.
The herb requires infrequent watering to stay healthy and produce strong and unique aromatic leaves.
Young rosemary plants may still survive with frequent watering, but everything changes when they mature.
Mature rosemary plants in temperate climates don’t need any form of additional watering since they can attain all their moisture requirements from rainfall, even during the dry summer months.
Rosemary pots tend to dry out quickly since the plant prefers full sun. Therefore, watering once every two weeks is appropriate during spring and summer. If you water your rosemary more than twice a month, you are most likely overwatering it.
If the plant is watered frequently, the soil stays moist/saturated with water, interfering with the roots’ ability to perform their functions.
This will eventually lead to root rot and other fungal diseases. If your rosemary turns black or brown, it could be signs of root rot or fungal infection. You must act quickly to save your plant from imminent death.
The best way to prevent overwatering is to check the soil before you water. A moisture meter or your finger can help determine if it needs more water.
If the top inch of the soil feels dry, then add some water. Otherwise, hold off until after a couple of days when you can check again.
Reason #3: Pests and Diseases
Although rosemary plant is known to be somehow resistant to pests and diseases, it can still fall victim to certain common pests and fungi.
The most notorious rosemary pest is the whitefly. This small insect is usually found on the underside of rosemary leaves, causing significant damage as a result of its feeding activities.
The whitefly feeds on plant sap using its piercing mouthpart leading to the yellowing and wilting of the leaves. It may also spread plant diseases such as tomato spotted wilt virus and other viral infections.
Rosemary plants are also prone to root rot, fungal infections, and other types of disease. High humidity levels (overwatering) or too much shade can provide favorable conditions for fungus and bacterial growth, leading to diseases.
If you notice your rosemary has wilted leaves, black spots on its stems, or yellowing of the leaves, it could be a sign of a disease.
To prevent pests and diseases from attacking your rosemary plants, ensure that you maintain good hygiene practices around.
Furthermore, avoid overwatering, use sterile potting soil, and move them away from overly wet areas. You may also need to apply a fungicide or insecticide to prevent further damage if the above measures don’t work.
Reason #4: Extreme Winter
Rosemary is a typical Mediterranean herb that thrives in relatively sunny locations. This plant is cold-tolerant since it belongs to the hardiness zone of 8-11. Anything below freezing temperatures can be catastrophic.
However, some varieties of this herb, such as the Madeline Hill and “Arp,” are quite hardy and can survive in low temperatures. In fact, these two varieties can survive in temperatures of up to -5 Degrees Fahrenheit.
If you live in a location where temperatures drop significantly during winter, you must ensure that your rosemary plant is protected from frost and snow. Consider bringing them indoors or to a warmer spot like the basement or garage.
The plant will become dry and brittle if you ignore it during winter and turn yellow or brown. The early signs of winter neglect will only kill a few branches. However, further neglect will completely kill the roots and the entire plant.
If you have planted your rosemary outdoors, in-ground making it impossible to move them indoors during winter, ensure you provide enough shelter that helps them avoid harsh winter winds.
If you discover signs of frost damage on your plant, quickly cut off the damaged stems and leaves and provide more protection.
Avoid pruning your rosemary during winter when there is still a risk of frost damage. The pruned areas will become susceptible to frost damage.
Pruning should be done in spring or summer when the weather is warm enough to stimulate new, healthy growth.
Consider mulching in fall with about three inches of mulch added on top of the soil.
Reason #5: The Soil Is Too Acidic
Rosemary grows in mildly acidic soil with a soil pH of between 6 and 7.5. If the soil is too acidic, it will limit essential nutrients from being available to your plant. This can lead to stunted growth, yellowing of leaves, and in some cases, death.
If you are not sure about the exact pH of your preferred soil, go for the typical garden soil that is mostly pH neutral or slightly acidic. This will provide your plant with the balance it needs to thrive.
You may also consider adding organic matter and compost to improve soil fertility. If you have been using chemical fertilizers, switch to natural fertilizers.
Organic fertilizers will ensure that your soil is adequately aerated and nutrients are available in adequate amounts.
Test your soil to know the exact pH level and make the necessary adjustments. Organic mulch can also help maintain a more neutral pH by decreasing acidity levels in the soil.
Reason #6: Excessive Pruning
While you can harvest your rosemary anytime during the active growing season, be careful not to overdo it.
Rosemary plants respond to pruning by producing more foliage and branches, which means you will get a bushy plant. But if you over-prune it, the plant won’t produce enough new growth, and its overall health will be affected.
When pruning rosemary, always use clean scissors and make sure to avoid cutting more than one-third of the plant’s foliage. Prune away dead and damaged stems and any overly long branches.
Prune only in spring or summer when the weather is warm enough for new growth. Doing so will ensure that your rosemary has enough time to recover before winter.
Reason #7: Overcrowding
Lastly, a rosemary plant may also die due to insufficient space between the plants. This is especially true for outdoor rosemary plants.
Overcrowding prevents optimal airflow to the plant leading to relatively slow water evaporation at the bottom of the plant, which is a recipe for fungal infections and root rot.
Therefore, ensuring your rosemary plants are spaced out nicely is always good to allow enough air and sunlight to reach each plant.
Rosemary is a hardy, fragrant herb that grows well both indoors and outdoors. However, if you are having trouble growing it, there could be several causes to examine. From too much or too little water to acidic soil or frost damage.
Keeping an eye out for these common issues and making the necessary changes to your growing condition can help you successfully grow a healthy rosemary plant.
Last update on 2023-07-27 / Affiliate links / Images from Amazon Product Advertising API