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Boxwood leaves turn brown for several specific reasons that often require closer inspection.
Boxwood leaves turning brown can happen gradually or seemingly overnight depending on the cause.
If you’ve noticed your boxwood leaves are turning brown, you’re likely wondering what went wrong.
Boxwood leaves turn brown due to environmental stress, pests, diseases, or even improper care.
In this post, we will break down the most common reasons your boxwood leaves turning brown and what you can do about it.
Let’s dive in and get your boxwood back to its healthy green self.
Why Your Boxwood Leaves Are Turning Brown
Before you panic, understand that boxwood leaves turning brown is a symptom of several possible underlying issues.
Identifying the specific cause is the first step to fixing the problem.
1. Winter Burn and Environmental Stress
One of the most common reasons for boxwood leaves turning brown is winter burn.
Harsh winter winds and bright winter sun can dry out the leaves when the ground is frozen.
Since the roots can’t pull up water from frozen soil, the leaves lose moisture faster than they can replace it.
This results in brown, scorched-looking foliage, especially on the side facing the wind or sun.
Boxwood leaves turning brown from winter burn often appear bronzed or straw-colored.
2. Fungal Diseases Like Boxwood Blight
A serious culprit behind boxwood leaves turning brown is boxwood blight, a fungal disease.
This disease causes dark brown or black spots on the leaves, followed by rapid leaf drop.
If your boxwood leaves are turning brown and falling off in large numbers, blight is a strong possibility.
Another common fungal issue is Volutella canker, which causes leaves to turn brown and stems to die back.
Boxwood leaves turning brown due to fungus often have a distinct pattern, like spots or streaking.
3. Pest Infestations
Tiny pests can also be the reason your boxwood leaves are turning brown.
Boxwood leafminers are small flies whose larvae tunnel inside the leaves, causing them to turn brown and blistered.
Boxwood mites, another pest, feed on leaf cells and give the foliage a stippled, brown appearance.
If you see boxwood leaves turning brown with small yellow or white specks, consider a mite infestation.
Inspect the undersides of leaves for signs of these tiny invaders.
4. Improper Watering and Soil Issues
Both overwatering and underwatering can cause boxwood leaves turning brown.
Boxwood prefer consistently moist but well-drained soil.
If the soil stays soggy, roots can rot, and the leaves will turn brown as the plant struggles.
Conversely, during a drought, boxwood leaves turning brown is a sign the plant is dehydrating.
Poor soil drainage and compacted roots are a very common reason for boxwood leaves turning brown.
5. Nutrient Deficiencies or Root Damage
Boxwood leaves turning brown can also indicate a lack of essential nutrients like nitrogen.
Root damage from construction, digging, or lawn equipment can also trigger a browning response.
When roots are stressed, they can’t deliver water and nutrients, leading to boxwood leaves turning brown.
This often shows up first on the inner or lower leaves of the plant.
How to Diagnose Brown Boxwood Leaves
Now that you know the causes, let’s look at how to figure out which one is affecting your plant.
1. Check the Pattern of the Browning
Boxwood leaves turning brown only on one side usually points to winter burn or wind damage.
If the brown is scattered throughout the plant, pests or diseases could be the issue.
Boxwood leaves turning brown and dropping at the base of the plant might indicate blight.
2. Inspect the Stems and Leaves Closely
Look for tiny spots, webbing, or tunnels on the leaves of boxwood leaves that are turning brown.
Black streaks on the stems are a classic sign of boxwood blight.
Check the roots if the boxwood leaves are turning brown and the plant seems loose in the soil.
3. Consider the Time of Year
Boxwood leaves turning brown in late winter or early spring is almost always winter burn.
If you see boxwood leaves turning brown in late spring or summer, pests or disease are more likely.
What to Do About Boxwood Leaves Turning Brown
Once you identify the cause, you can take action to stop boxwood leaves turning brown further.
1. For Winter Burn
Prune the brown boxwood leaves in early spring once the risk of frost has passed.
The plant should push out new green growth if the roots are healthy.
Protect your boxwood next winter with burlap wraps or an anti-desiccant spray.
2. For Fungal Diseases
Remove and destroy all affected leaves of boxwood leaves turning brown from fungus.
Avoid overhead watering as wet leaves spread fungal spores easily.
Apply a fungicide labeled for boxwood blight, but this is often a last resort.
Good air circulation around your boxwood helps prevent future infections.
3. For Pests
Prune away branches with boxwood leaves turning brown due to leafminers.
Horticultural oil or insecticidal soap can control mites and scale.
For severe infestations, systemic insecticides may be necessary for boxwood leaves turning brown.
4. For Watering and Soil Issues
Improve soil drainage by adding organic matter if boxwood leaves are turning brown from wet feet.
Water deeply during dry spells, especially in the fall before the ground freezes.
Mulch around the base helps retain moisture and regulate soil temperature.
This simple step can prevent boxwood leaves turning brown from stress.
So, Why Are My Boxwood Leaves Turning Brown?
Your boxwood leaves turning brown can be caused by winter burn, fungal diseases, pests, watering issues, or root and nutrient problems.
Identifying the specific reason requires a close look at the damage and the environment.
Boxwood leaves turning brown doesn’t always mean the plant is dying, but it does require prompt attention.
By checking the browning pattern, inspecting for pests and diseases, and adjusting your care routine, you can stop boxwood leaves turning brown from becoming a permanent problem.
Take action now, and your boxwood will likely reward you with healthy green growth again.