What Causes Rosemary Leaves To Turn Brown?

Rosemary is a Mediterranean herb with many uses. It’s used to flavor foods and can be used as a garnish or incorporated into teas or medicinal remedies. A healthy Rosemary plant will have vibrant green leaves and a pleasant aroma, but if your plant isn’t thriving, it’s likely suffering from one of the many issues that can cause browning leaves on Rosemary plants. Here are some common causes for Rosemary leaves turning brown:

Too Much Water

Rosemary is a semi-arid plant; therefore, it needs to be watered. However, the Rosemary leaves can turn brown if you water them too frequently because the plant has a shallow root system vulnerable to over-watering.

The best way to water your Rosemary plants is by setting up drip irrigation on the soil surface around the plant and letting the water soak in from there. This will allow even watering without putting too much stress on its shallow roots.

Rosemary should also be kept evenly moist. If you notice some of your rosemaries are wilting while others are fine, this may mean they’re getting too much or not enough moisture, respectively, so make sure your watering routine is well balanced across all of your plants.

Too Much Sunlight

If you’ve been growing Rosemary in a sunny area, the leaves on your plant are likely turning brown. Rosemary is a low-light plant that requires at least 6 hours of shade per day to thrive. If you’re growing Rosemary outdoors and want to keep the plant healthy, make sure that it has plenty of shade (at least 6 hours) during the day.

If you can’t move the plant indoors or into another area with more shade, try covering it with something like a tree branch or other object to protect it from too much sun exposure.

Injury From Sunburn

Sunburn is the most common cause of browning leaves. In this case, the plant has not been properly hardened off, and transplanting in spring or summer can cause sunburn. If you’re growing Rosemary in a pot or container and it’s getting too much direct sunlight or not enough shade, consider moving it to a shadier location until you can harden off the plant.

Injury from sunburn can also be caused by a lack of water or too much water. If your Rosemary plants appear to be wilted even though they have been watered regularly, try watering them less frequently for several days before increasing their frequency again.

This will give them time to recover from any dehydration stress they experienced due to over-watering and allow them time to absorb moisture easily so that you don’t get any further trouble with wilting.

Fertilizer Burn

While fertilizing your Rosemary plant is a good idea, it’s important to be careful about how much fertilizer you give your plant. Too much fertilizer or the wrong fertilizer can be a reason behind Rosemary leaves turning brown.

Rosemary is a slow-growing perennial shrub, which means that it doesn’t need as much attention as other plants might need to thrive. A major cause of brown leaf tips on Rosemary plants is the result of too much fertilizer being applied at once. Because of this, it’s important not to overfeed your plant with too many nutrients at once.

Another common reason for browning out leaves is when there isn’t enough balance between nitrogen and potassium levels in the soil where you’ve planted them–this imbalance leads directly back into the previous paragraph’s point about overfeeding.

Specifically speaking: if you have poor drainage around where these plants live outside, they may become more susceptible because waterlogged conditions tend towards excesses like salinity (which can also cause tip burn).

If these conditions persist long enough, a certain type of foliar disease could potentially form later down the line due to the combined factors being present together at once. That would explain why sometimes only certain parts of a branch turn brown rather than evenly distributed throughout all other branches so keep an eye out for signs like discoloration accompanied by wilting or spotting.

Fungal Infection

A fungal infection can also cause the leaves of your Rosemary plant to turn brown. This may be caused by rust or other fungus that infect roses and other plants. In order to prevent this problem from happening again, try using a fungicide spray on your Rosemary plants once every week during the spring and summer months when the weather is hot and humid.

Diseases Such As Botrytis Blight And Powdery Mildew

If you have a Rosemary plant and it’s turning brown, there could be a number of reasons. It is important to keep your plants healthy so that they will not suffer from diseases such as botrytis blight and powdery mildew, especially in climates where Rosemary is not winter hardy.

Botrytis blight is a fungal disease that causes your Rosemary leaves to turn brown and fall off early. It’s caused by overwatering and poor drainage, which can lead to root rot or stem rot, as well as other problems such as soggy soil conditions throughout the year (not just during rainy seasons).

The best way to prevent this disease is proper care: make sure that your potting mix drains well; don’t leave wet pots sitting around; rotate pots regularly so they get plenty of light exposure; water when the soil feels dry 1 inch below the surface but avoid getting runoff on leaves—instead try watering from underneath.

Insect Pests Such As Aphids And Spider Mites.

Check for these pests first if you notice your Rosemary leaves turning brown. Aphids and spider mites are tiny insects and arachnids that suck the sap from plants. This can cause damage to your Rosemary plant if left untreated, so it’s important to take care of them as soon as possible.

If you find these pests on your Rosemary plant, there are several things you can do about it:

  • Use a strong spray of water from a hose or watering can. You may have to repeat this process multiple times before they’re all gone.
  • Spray with insecticidal soap or neem oil (both natural products). You’ll have to repeat this process several times over several days since both tend not to kill immediately upon contact but rather over time through systemic poisoning effects on their bodies’ systems (insects) or sap-sucking mouth parts (mites).

Chemical Injury

It can turn brown when the Rosemary plant comes in contact with certain chemicals such as fertilizers, herbicides, or pesticides. Chemical injuries are usually treated with water or salt solutions to remove the toxic materials from leaf tissue.

If you suspect your plant has been exposed to herbicides or antifreeze, contact a professional who can identify and remove the substance.

Environmental Stress

There are several possible causes of browning Rosemary leaves. These include:

  • Environmental stress from temperature extremes or drafts from nearby heat sources. If your Rosemary is getting too cold, the leaves may turn brown, and the stems may become brittle and break easily. If your Rosemary is getting too hot, the leaves will also turn brown and begin to wilt. This usually happens in the late afternoon when direct sunlight hits the plant.
  • Environmental stress from dry air or lack of humidity. If there isn’t enough moisture in the air, your plants will suffer from drought stress — which can lead to leaf drops and even death if left untreated long enough. This can happen indoors if you have a forced-air furnace with no humidifier installed or if you use a dehumidifier in your home or office. It can also happen outdoors if you live in an arid climate or if there’s been a recent drought that has depleted soil moisture levels on your property.

Root Rot Due To Overwatering Or Poor Drainage

Rosemary needs good drainage to thrive. If your Rosemary plant has root rot, it’s likely because you overwatered or poor soil drainage. If its roots are rotting, then the plant will die as well. So if you want to keep your Rosemary healthy, make sure that its pot has good drainage and that you don’t overwater it by watering from the top of its soil instead of allowing excess water to drain out through its bottom holes.


Our Final Thoughts.

If you’re growing Rosemary and notice that some of the leaves are brown, be sure to check the soil moisture level first. If your plant is getting enough water but still has brown leaves, other issues may be at play. One common reason for brown leaves is fertilizer burn—especially if you use chemical fertilizer or an ammonium-based organic fertilizer. Fertilizer burn can also happen when you overfertilize your plants with too much nitrogen. In conclusion, it’s essential not to throw away that sprig of Rosemary just yet. Rosemary leaves turn brown when they’re exposed to moisture, light, or heat. You can prolong their life by keeping them in a cool, dark place in your kitchen or in a porous container on your counter.