Troubleshooting Brown Rosemary: Understanding the Cause and Corrective Action

Rosemary, the aromatic evergreen in the mint family, is a popular herb used in a variety of cuisines and medicinally. However, if you've noticed your rosemary turning brown, don't despair. This article will help you identify the causes and provide solutions for your brown rosemary.

One common cause of brown foliage on rosemary is underwatering. If your rosemary is not receiving enough water, its leaves may turn brown. To prevent this, ensure the top 2 inches of soil dry between waterings.

On the other hand, too much water can also cause brown foliage due to root rot. Excess water can deplete soil nutrients, leading to a brown rosemary. Overwatering can lead to root rot, which is often indicated by yellowing leaves, leaf drop, and brown or black roots accompanied by a noxious odor of decay. To avoid this, increase drainage, especially for container-grown plants, and ensure your rosemary has adequate drainage holes and is potted in a well-draining medium.

Potted plants are more susceptible to cold temperatures than those planted in the garden. Rosemary is winter hardy to only about 20 F, USDA zones 7-10. If your rosemary is not protected from chilly temperatures, it can suddenly and drastically turn brown. To prevent this, bring your rosemary inside or provide it protection before cold temperatures.

Gradually acclimating rosemary to darker conditions and reducing irrigation before bringing it indoors can help prevent root rot. Fungus gnats can spread rots such as Phytophthora in rosemary plants, so ensure your rosemary is well-drained to avoid these pests.

If some roots are healthy and white, the infected portion can be cut off and the "good" portion of the plant can be repotted in new soil. However, if the entire root bundle of a rosemary plant is mushy and dark colored, the plant cannot be saved.

Luisa, the author of this article, shares her concern about her Roman chamomile turning brown. If you're experiencing similar issues with your rosemary, don't hesitate to take action.

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