Why Is My Rosemary Turning Brown? How To Fix It

Rosemary Turning Brown? Expert Tips To Fix It

Generally easy to grow, this herb plant is not without its issues, a common one being rosemary turning brown. Rosemary is a beautiful, aromatic evergreen in the mint family that’s used medicinally and in a variety of cuisines. 

A commonly grown, well-loved kitchen herb, it’s tough to see it begin to fail. If you're asking “Why is my rosemary turning brown?” don’t worry, we’ve got you covered. Read on to find out why your rosemary is turning brown.

Is My Rosemary Dead?

Why is my rosemary plant dying? I’ve said it myself and not too long ago. My usually robust, bright green rosemary was turning a dull, drab brown. What could the problem be? 

There are a few reasons for a rosemary plant turning brown. In my case, I believe the culprit was too much water. The rosemary was actually one of two; twins in matching containers at the entry to my home. The containers get full sun and as you can imagine, they dry out quickly. It seems that both my husband and myself were watering the pots. Too much water equals brown foliage due to root rot. 

We’ll talk about root rot some more but let’s see what other reasons there might be for browning foliage on a rosemary plant. 

Common Reasons for Rosemary Turning Brown

Native to the Mediterranean hillsides of Portugal and Spain, rosemary is winter hardy to only about 20 F, USDA zones 7-10. When it’s not protected from chilly temperatures rosemary can suddenly and rather drastically turn brown. Needle drop often follows this color change. Effectively the plant has been killed by cold. 

Another reason for rosemary to turn drab brown is also weather-related. Although rosemary has acclimated to the warm Mediterranean sun, sometimes there can be too much of a good thing. Even rosemary can suffer a sunburn, especially if it is container-grown, the weather is at its hottest, and the plant is already stressed. 

Back to how water causes brown foliage on rosemary: As we mentioned, this may be due to overwatering and the resultant root rot. Excess water can also deplete soil nutrients in plants either container grown or in the ground. So a brown rosemary may also indirectly be the result of a lack of nutrients. 

If indeed the case of browning is related to overwatering, the result is that the root system shrinks, leading to brown foliage. Underwatering can also cause brown foliage. 

How to Fix Rosemary That’s Turning Brown

Rosemary is accustomed to dry conditions and doesn’t take kindly to a deluge of water. When you water the herb be sure to allow the top 2 inches (5 cm) of soil to dry between waterings. Increasing the amount of drainage will also keep the plant from drawing. This is especially important for container grown rosemary which should have adequate drainage holes and be potted in a well-draining medium. 

If you suspect the issue to be weather related, be sure to bring the plant inside or provide it some protection before temperatures drop in the fall. Start well ahead of time and allow the plant to gradually acclimate by reducing irrigation and gradually letting it get used to the darker conditions of the home. If the plant is too wet when you bring it in it will surely get root rot. 

Once the plant has root rot, there isn’t much hope. You can try to save it by inspecting the roots. If the entire root bundle is mushy and dark colored, sadly the plant can’t be saved. If some roots are healthy and white, you can attempt to cut off the infected portion and repot the “good” portion of the plant in new soil.

How to Prevent Rosemary From Turning Brown

Keep an eye on the temperature gauge and protect your rosemary from cold temperatures by bringing it indoors. Know your USDA zone as well. Is rosemary cold hardy in your area? If not, then treat it as an annual or dig it up and try to overwinter it in the house. 

Don't overwater rosemary! This tough herb has spent millenia acclimated to the rugged, gritty hills of the Mediterranean. Remember to use the finger test before watering. Allow the top 2 inches (5 cm) of soil to dry before irrigating again. 

Use a well-draining potting mix and container with adequate drainage. Control fungus gnats which can spread rots such as Phytophthora. 

FREQUENTLY ASKED QUESTIONS

Why Is My Potted Rosemary Dying?

Potted anything has a tough time of it but in the case of rosemary, the issue is likely overwatering. Containers make it easy to over- or under-water plants. Only water when the top 2 inches (5 cm) of soil has dried. Potted plants also lose nutrients as they drain. Depending on the material of the pot, some get incredibly hot which can burn even the resilient rosemary. Potted plants are also more susceptible to cold temperatures than those planted in the garden. 

What Are the Signs of Root Rot in Rosemary?

Root rot usually begins as yellowing of leaves, followed by leaf drop. The entirety of the foliage may also become brown. The roots will turn brown or black rather than healthy white and are accompanied by a noxious odor of decay.