Why Is My Bush Turning Brown? Common Causes & Fixes

Browning in landscape shrubs almost always traces back to a stress the plant cannot escape on its own, whether that is parched soil, waterlogged roots, a fungal pathogen, or something toxic in the ground. The good news is that the pattern of browning usually points to the cause. Leaves that crisp from the tips inward suggest a water or salt problem; scattered dark spots suggest disease; and sudden, uniform browning after a neighbor sprays their lawn hints at chemical drift. Figuring out which stress is responsible is the hard part. The fix, once you know, is usually straightforward.

Drought Stress and How It Damages Shrubs from the Inside

The most common reason a bush turns brown is that it is not getting enough water. This seems obvious, but the internal damage is worth understanding because it explains why a drought-stressed shrub sometimes does not bounce back even after you start watering again. When soil dries out, a plant’s roots cannot pull water fast enough to keep up with what the leaves lose through evaporation. As the water column inside the stems gets stretched thinner and thinner, air bubbles can form inside the tiny tubes that transport water, a process researchers call cavitation. Once an air bubble blocks a tube, that section of the plant’s plumbing is permanently shut down.

Research on shrubs native to dry climates shows just how far water stress has to go before this damage kicks in. In a study of two Mediterranean species during severe drought, one species began losing water-transport capacity at a stem water potential of about −3.5 megapascals, while a tougher species held out until −5 megapascals. By the time conditions got extreme, both species had lost nearly all hydraulic function.¹ In plainer terms, air enters the plant’s water-conducting tubes once the drought is severe enough, and the resulting blockage is what kills branches and turns foliage brown.²

The practical takeaway: if your bush has been dry long enough for entire branches to go brown and brittle, watering may save the living parts of the plant but will not revive dead wood. Prune out the brown sections and give the shrub deep, infrequent soakings rather than shallow daily sprinkles. Deep watering encourages roots to grow downward toward moisture instead of staying near the surface where they dry out fastest.

Overwatering and Waterlogged Roots

Ironically, too much water produces browning that looks a lot like drought stress. When soil stays saturated for days at a time, oxygen gets squeezed out of the root zone. Roots need oxygen to function. Without it, they begin to rot, and a bush with rotting roots cannot absorb water no matter how wet the soil is. The leaves respond the same way they would in a drought: they wilt, turn yellow, and eventually brown.

You can usually tell the difference by checking the soil a few inches below the surface. If it feels soggy or smells sour, overwatering or poor drainage is the likely problem. Heavy clay soils and low spots in the yard are the usual suspects. Shrubs planted against a foundation where gutter runoff pools are especially vulnerable. The fix involves improving drainage around the root zone, sometimes by amending the soil with coarse organic matter, sometimes by regrading the area so water flows away from the plant. If the bush is in a container, make sure the pot has adequate drainage holes and that it is not sitting in a saucer full of standing water.

Road Salt and De-Icing Chemical Damage

If your browning shrub sits near a road, driveway, or sidewalk that gets salted in winter, salt damage is a strong possibility. Sodium from road salt accumulates in the soil and gets drawn up into the leaves, where it disrupts normal cell function. A study of horse chestnut trees growing near salted roads found that sodium levels in damaged leaves were 42 to 100 times higher than in leaves from unsalted control sites. The more sodium the leaves contained, the worse the visible damage, and the correlation was strong.³

Salt damage often shows up as browning along leaf margins, because sodium concentrates at the edges where water evaporates. On evergreen shrubs like boxwoods and yews near a roadside, the side facing traffic may turn brown while the sheltered side stays green, which is a dead giveaway. The damage typically becomes visible in late winter or early spring, right when salt applications peak.

Fixing salt damage is partly about flushing and partly about prevention. In spring, water the affected area heavily to leach sodium down through the soil profile, away from the root zone. Going forward, consider installing a burlap screen between the road and your shrubs during salt season, or switch to a more salt-tolerant species in those high-exposure spots. Applying gypsum to the soil can also help displace sodium from soil particles over time.

Soil pH and Micronutrient Problems

Sometimes a bush turns brown not because anything dramatic happened but because it has been slowly starving. Soil pH plays a huge role in whether nutrients actually reach a plant’s roots. As soil becomes more alkaline, most micronutrients become less available to plants, even if those nutrients are technically present in the soil.⁴ Acid-loving shrubs like azaleas, rhododendrons, blueberries, and camellias are especially prone to this. Plant them in neutral or alkaline soil and they will gradually yellow, then brown, as iron and manganese become locked up in forms their roots cannot absorb.

The pattern of browning gives a clue about what is going on. Micronutrient deficiencies tend to show up first on the youngest leaves at the top of the plant, while toxicity from excess nutrients more often appears on older, lower leaves.⁴ If you notice the newest growth looking pale and sickly while older leaves still look reasonable, a nutrient availability problem driven by pH is a good bet.

A basic soil test from your local extension office will tell you where your pH stands and which nutrients are in short supply. Sulfur amendments can lower pH for acid-loving plants, while lime raises it for species that prefer sweeter soil. Foliar sprays of chelated iron can provide a quick temporary fix for iron chlorosis while you work on adjusting the soil over the longer term.

Fungal Disease, Especially Boxwood Blight

If your bush develops distinct dark spots on its leaves followed by rapid leaf drop and dark streaks on the stems, you are likely dealing with a fungal pathogen rather than an environmental stress. Boxwood blight is one of the most devastating examples. Caused by a fungus called Calonectria pseudonaviculata, it produces circular dark spots on leaves, followed by defoliation, along with brown-to-black streaks running along the shoots.⁵ The disease can strip a mature boxwood hedge bare in a matter of weeks under warm, humid conditions.

What makes fungal blights tricky is that they spread fast through splashing water and contaminated tools. If one boxwood in a row starts showing symptoms, the spores are likely already on its neighbors. For boxwood blight specifically, there is no cure for an infected plant. The standard recommendation is to remove and bag the infected shrubs, avoid composting the debris, and sanitize your pruning tools with a ten-percent bleach solution between plants. Some boxwood cultivars have been bred for better resistance, so if you are replanting, ask your nursery about varieties selected for blight tolerance.

Other fungal diseases follow a similar playbook. Root rot caused by Phytophthora species attacks a wide range of landscape shrubs and thrives in wet soil, which connects back to the overwatering problem. Needle blights affect junipers and arborvitae, turning individual branches brown while the rest of the plant looks fine, a pattern called “flagging.” The consistent principle is that fungal browning tends to appear in distinct patches or patterns rather than as uniform stress across the whole plant.

Herbicide Drift from Nearby Applications

A less obvious cause of sudden browning is accidental exposure to herbicides sprayed nearby. This does not require a direct hit. Many modern herbicides, particularly the hormone-mimicking types used on lawns and agricultural fields, can drift significant distances as fine droplets or vapor, especially on warm, windy days. Even trace amounts of these chemicals can cause dramatic damage to sensitive plants. Research on herbicide drift from drone-based sprayers has documented that crops like soybeans are exceptionally sensitive to hormone-type herbicides, and even tiny exposures can stunt growth and cause serious harm.⁶

Herbicide damage on shrubs has some distinctive tells. Leaves may curl, twist, or develop an unusual cupping shape before browning. Growth may become distorted, with new shoots coming in stunted or misshapen. The damage often appears suddenly, within days of a nearby application, and affects only the side of the plant facing the source. If your neighbor recently treated their lawn or a nearby farmer sprayed a field and your bush started looking strange shortly after, herbicide drift deserves strong suspicion.

There is not much you can do to reverse herbicide damage once it has happened. Mildly affected plants may grow out of it over a season as they produce new, unaffected foliage. Severely damaged plants may need to be replaced. Prevention means communicating with neighbors about spray schedules and asking applicators to avoid spraying on windy days or when temperatures are high enough to increase vapor drift.

Heat Reflected from Hardscaping and Artificial Surfaces

Shrubs planted next to driveways, brick walls, artificial turf, or dark-colored mulch can brown on one side while the rest of the plant stays green. This happens because hard, dark surfaces absorb solar energy and re-radiate it as heat, creating a microclimate several degrees warmer than the surrounding air. Research measuring the energy balance of urban landscaping materials found that artificial turf had the lowest reflectivity and highest net radiation absorption of the materials tested, and both artificial turf and hardwood mulch had the highest surface temperatures.⁷

A bush planted in a narrow strip between a south-facing brick wall and a concrete sidewalk is essentially living in a frying pan. The reflected and re-radiated heat dries out the foliage on that side faster than the plant can replace the lost moisture, producing a lopsided browning pattern that people often mistake for disease. Foundation plantings on the south and west sides of buildings are most vulnerable, especially during summer heat waves.

If you suspect radiated heat, feel the nearby surface with your hand in the afternoon sun. If it is too hot to touch comfortably, it is too hot for tender foliage pressed up against it. Moving the bush a couple of feet away from the heat source can make a dramatic difference. Where that is not possible, a layer of light-colored gravel or organic mulch between the plant and the hard surface helps reduce how much energy reaches the foliage. Choosing heat-tolerant species for these microclimates also saves frustration.

Winter Burn on Evergreens

Evergreen shrubs like boxwood, holly, rhododendron, and arborvitae are particularly susceptible to a type of browning that shows up in late winter or very early spring. The foliage turns bronze or brown, sometimes only on the side facing prevailing winds or direct afternoon sun. This happens because on bright, cold winter days the leaves lose moisture through evaporation, but the frozen ground prevents the roots from replacing it. The result is essentially a localized drought injury occurring in the middle of winter, which is why it is sometimes called winter desiccation or winter burn.

Wind makes it worse by stripping moisture from the leaves faster. Exposure to afternoon sun is also a factor because it warms the leaf surface enough to increase water loss even when air temperatures are below freezing. Shrubs planted on the south or west side of a building, or in exposed windy corridors between structures, are the ones that get hit hardest.

The good news is that winter burn is rarely fatal. Most affected shrubs push new growth in spring that replaces the damaged foliage. Resist the urge to prune everything back immediately in March. Wait until new growth starts, then trim out whatever is truly dead. For prevention, water your evergreens deeply in late fall before the ground freezes, so they go into winter with as much stored moisture as possible. Anti-desiccant sprays, which coat the leaves with a waxy film to slow moisture loss, can help in exposed locations but need reapplication after heavy rain or snow.

Diagnosing the Pattern

Since so many different problems produce brown foliage, the browning pattern is your most useful diagnostic tool. Here are the patterns and what they suggest:

• Leaf edges brown first: Usually a salt, fertilizer burn, or drought issue. The tips and margins dry out before the center of the leaf because that is where moisture evaporates fastest.
• Youngest leaves affected: Points toward a micronutrient deficiency, often iron or manganese tied up by high soil pH.
• Oldest, lower leaves affected: Can indicate nutrient toxicity or nitrogen deficiency, since plants pull mobile nutrients from older leaves to feed new growth.
• Distinct spots or lesions: Fungal or bacterial disease. Look for dark, round spots sometimes with a yellow halo, or streaks on stems.
• One side of the plant: Heat reflection from a nearby surface, salt spray from a road, wind desiccation, or herbicide drift. Whichever side faces the source takes the hit.
• Whole plant, sudden onset: Root damage, severe drought, or chemical exposure. Something catastrophic happened below ground or the plant got a dose of something toxic.
• Scattered individual branches: Possible stem canker, borer insect damage, or a vascular disease blocking water flow to just those branches.

Combining the browning pattern with timing often clinches the diagnosis. Browning that appears in late winter is almost always weather-related. Browning that starts a few days after a lawn treatment points to chemical exposure. Browning that creeps through a hedge from one end to the other over several weeks has the hallmarks of an infectious disease spreading plant to plant.

When to Call a Professional

Most browning problems can be sorted out with a soil test, a closer look at watering habits, and a bit of pruning. But some situations genuinely benefit from expert help. If your shrubs are declining and you cannot identify a clear environmental cause, a certified arborist or your local cooperative extension office can take tissue samples and test for specific pathogens. Boxwood blight in particular requires lab confirmation because it looks similar to several less serious leaf spots, and misidentifying it can mean the disease spreads to every boxwood on your property before you realize what you are dealing with.

Extension offices also run soil tests for a few dollars that measure pH, nutrient levels, and sometimes salt content. The results come with plain-language recommendations tailored to your region. Spending a small amount on a soil test before buying bags of amendments at the garden center saves money and prevents the common mistake of adding fertilizer to a bush that is actually suffering from a pH problem or root rot, neither of which fertilizer will fix.