Boxwood Turning Brown

Seeing your boxwood turning brown can be a real worry. It’s a common issue, but the fix depends on the cause. Let’s figure out why it’s happening and what you can do to save your plant.

Boxwoods are tough, but they can struggle with pests, diseases, or environmental stress. The good news is many brown boxwoods can recover with the right care. This guide will walk you through the steps to diagnose and treat the problem.

This heading covers the main symptom, but the reasons behind it vary widely. Correct diagnosis is your first and most important step. Jumping to conclusions can lead to wasted time and incorrect treatment.

Common Causes of Brown Boxwood Leaves

Here are the most likely culprits. Look closely at your shrub to see which signs match.

Winter Burn: This is very common. Dry winter winds and frozen ground rob leaves of moisture, causing browning, especially on the south-facing side.
Boxwood Blight: A serious fungal disease. Look for dark leaf spots with black streaks on stems and rapid defoliation.
Volutella Blight: Another fungus. Causes pinkish spore clusters on the undersides of leaves and tan-colored lesions.
Root Rot (Phytophthora): Often from poor drainage. Leaves turn bronze then brown, and the plant wilts despite wet soil.
Boxwood Leafminer: A pest. The larvae feed inside leaves, causing yellow blotches that turn brown and blister.
Poor Planting or Watering: Planting too deep, drought stress, or overwatering can all lead to browning.
Salt Damage: From road salt spray or excessive fertilizer, causing leaf scorch.

Step-by-Step Diagnosis Guide

Follow these steps to narrow down the cause.

Check the Pattern: Is browning on one side (likely winter burn), at the base (maybe Volutella), or all over?
Examine the Leaves: Look for spots, streaks, blisters, or tiny insects. Use a magnifying glass.
Inspect the Stems: Peel back bark slightly. Green underneath means it’s alive; brown or black streaks indicate disease.
Consider the Soil: Is it soggy or bone dry? Dig a small hole near the roots to check moisture.
Review Recent History: Did you have a harsh winter? Was the plant recently moved or fertilized?

Expert Care Solutions for Each Problem

Once you’ve identified the likely issue, use these targeted solutions.

For Winter Burn & Environmental Stress

This is about protection and gentle recovery.

Water deeply in late fall before the ground freezes to ensure the plant is hydrated.
Apply a 2-3 inch layer of mulch (like shredded bark) to insulate roots and retain moisture. Keep it away from the trunk.
Use burlap screens on windy sides to shield plants from drying winds.
In spring, prune out dead branches, but wait until new growth starts so you can see what’s truly alive. Water consistently during dry spells.

For Fungal Diseases (Boxwood Blight & Volutella)

Sanitation is critical here to prevent spread.

Prune Carefully: Sterilize your shears with a bleach solution (1 part bleach to 9 parts water) between every cut. Remove and destroy all infected branches and fallen leaves. Do not compost them.
Improve Airflow: Thin out the shrub slightly to allow air to circulate in the center, which reduces humidity where fungi thrive.
Apply Fungicide: For severe cases, a preventative fungicide labeled for boxwood blight or Volutella may be needed. Apply as directed, starting in spring.
Water at the Base: Avoid overhead watering that wets the leaves.

For Root Rot

This is often a soil and drainage issue.

Improve drainage immediately. You may need to regrade the area or consider raised beds.
Reduce watering frequency. Let the soil dry out a bit between waterings.
In early stages, a soil-applied fungicide might help, but severe cases are hard to reverse. Sometimes replacing the plant with a resistant variety is the best option.

For Pest Problems (Leafminer, Mites)

Timing is everything with pests.

Confirm the Pest: Leafminer damage shows as swollen blisters. Spider mites cause fine webbing and stippling.
Prune Affected Growth: For leafminers, prune and destroy infested leaves in early spring before adults emerge.
Use Targeted Treatment: Apply a horticultural oil spray in late spring to smother emerging leafminer adults and eggs. For mites, a strong blast of water or insecticidal soap can be effective.
Encourage Beneficial Insects: Ladybugs and other predators help control mite populations.

Preventative Care to Keep Boxwoods Healthy

An ounce of prevention is worth a pound of cure, especially for boxwoods.

Plant Smart: Choose resistant varieties like ‘Green Gem’ or ‘Green Mountain’. Plant in well-drained soil, and never deeper than it was in the pot.
Water Wisely: Deep, infrequent watering is better than frequent sprinkles. Soaker hoses are ideal.
Mulch: Maintain a consistent mulch layer to regulate soil temperature and moisture.
Fertilize Lightly: Over-fertilizing can cause burn and promote succulent growth that attracts pests. A light application of balanced fertilizer in spring is usually sufficient.
Prune for Health: Thin for airflow rather than shearing tightly, which creates dense outer growth that blocks light and air from the center.

When to Prune vs. When to Replace

Not every brown boxwood can be saved. Here’s how to decide.

Prune and Wait: If the stems are still green under the bark and there are healthy buds, prune back dead material and give the plant a full growing season to recover. Many boxwoods will bounce back from winter burn or minor pest damage.

Consider Replacement: If the plant has lost more than 75% of its foliage, if the main stems are dead and brittle, or if it’s suffering from a severe case of Boxwood Blight in a landscape with other boxwoods, removal is often the safest choice. This prevents the problem from spreading to healthy plants.

FAQ: Your Boxwood Questions Answered

Can a completely brown boxwood come back?
It depends. Scratch the bark. If you see green, there’s hope. If all stems are brown and brittle down to the base, it’s likely dead. Patience is key; new growth can sometimes emerge from the roots if the crown is dead.

How do I know if my boxwood has a disease or just winter burn?
Winter burn typically browns the side facing the wind or sun and doesn’t cause leaf spots or stem lesions. Diseases like blight show distinctive spots and black streaks, and often cause leaves to drop quickly.

What is the best fungicide for boxwood blight?
Consult your local nursery or extension service for current recommendations, as products vary. Chlorothalonil and tebuconazole are common ingredients found in effective fungicides. Always follow the label instructions exactly.

Should I fertilize a browning boxwood?
Not immediately. First, diagnose and adress the stress causing the browning. Fertilizing a stressed plant can worsen the problem. Once it shows signs of recovery (new green growth), you can apply a light, balanced fertilizer.

How often should boxwoods be watered?
There’s no set schedule. Water deeply when the top 2-3 inches of soil feel dry. This might be once a week in hot weather, or much less in cool, rainy periods. Proper drainage is just as important as watering.

Dealing with a boxwood turning brown requires a bit of detective work. Start by looking closely at the plant and its surroundings. Match the symptoms to the cause, then apply the specific solution. With careful attention and the right care, you can often restore your boxwood’s health and enjoy its green beauty for years to come. Remember, preventative care is the most effective strategy of all.