How to Fix Brown Leaves on a Blackberry Bush (4 Ways)

I’m doing a permaculture design plan for a client with some blackberry bushes, and he was asking why some of them are getting brown leaves. To help him out, I put together this guide.

Blackberry bushes get brown leaves if the plant is stressed or dying. Common issues include improper watering and nutrients, as well as pests and diseases such as leafrollers. Ideally, only water blackberries when the first 2-4 inches of soil is dry and provide 2 inches of compost and 4-12 inches of mulch.

Let’s take a closer look at how we can identify the causes of brown leaves on blackberry plants and how it can be treated.

a blackberry plant with curled and brown leaves

Table of Contents

1. Improper Watering

Under-Watering

Under-watering blackberry bushes cause their roots to dry and die, which limits the amount of moisture the plant can send to its leaves. As a result, the leaves curl, brown, and drop. If left for too long, the blackberry plant will die.

While it’s difficult to tell the exact amount you should water blackberry plants, there is a good rule of thumb.

Only water blackberry bushes when the first 2-4 inches of soil is dry.

Since each plant has different soil, sunlight, wind, drainage, and other factors, it’s impossible to provide a set volume of water.

However, by checking the soil first, you’re ensuring you’re not under-watering.

If you find that your blackberry plant’s soil is drying too fast (usually within 1-2 days of watering), there are a couple of things you can do:

Compost
Mulch

Soil likes to be covered, and providing compost and mulch is the best way. Covering the ground allows the soil (and its beneficial microbes) to escape the drying effects of sun and wind. It also prevents soil erosion.

Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil.

Compost and mulch also dramatically improve the soil’s water retention, nutrients, and health. As a result, you don’t have to water (or fertilize) your blackberry bushes nearly as often.

Providing compost and mulch mimics forests: fallen branches, leaves, and animal manure build the soil.

However, there are times when adding mulch is not a good idea.

Over-Watering

Excess watering drowns the roots of the blackberry bush, leading to issues such as poor soil aeration and fungal growth (such as root rot). If not addressed, the blackberry plant develops yellow, brown, and dropping leaves. Eventually, the blackberry plant will die.

If you check your blackberry bush’s soil and notice it’s sopping wet for 1+ days, it likely has poor drainage.

Check your soil’s drainage by pushing a finger 2-4 inches into the soil. If it’s bone dry, increase your watering schedule. If it’s sopping wet, hold off on watering until it’s dry.

While the above is a good way to get a quick reading of your soil’s drainage, there’s a more extensive method.

Drainage Test

doing a soil percolation test in our backyard

Here’s how to do a drainage (percolation) test:

Dig a 12-inch by 12-inch hole
Place a yardstick in it and fill it with water
Measure the drainage over 1 hour

Good soil drainage is around 2 inches of drainage per hour. Any more and the soil is draining too fast, any less and it’s draining poorly.

Don’t worry if yours is way off, this is a guideline and not a rule. We have some areas with soil drainage of 5 inches per hour and plants still grow well.

If your soil is draining too quickly, increase its richness with compost and mulch. This encourages more organic matter and soil life (which holds more moisture). It also reduces the soil’s water content from evaporating.

If your soil is draining too slowly, you’ll also want to increase its richness. This is because the organic matter in the soil not only retains water but breaks up the larger clumps of soil—allowing for ideal drainage. However, avoid mulching your blackberry plant as it can trap moisture, preventing evaporation.

2. Improper Nutrients

Either too much or too little nutrients cause blackberry plants to get brown leaves. Excess nutrients chemically burn the plant’s roots, causing the plant to die off. Too few nutrients starve the plant.

Feed your blackberry bush a balanced fertilizer (such as a 10-10-10) as directed, or 2 inches of compost every 1-2 months. While chemical fertilizers have short-term benefits, they have been found to harm the soil long-term (and therefore the plant).

Because of this, I prefer to use compost and mulch. However, chemical fertilizer can be handy in the short-term.

As with all plants, blackberry plants have three primary nutrients: nitrogen, phosphorus, and potassium (abbreviated as NPK). Both chemical fertilizers and compost have sufficient nutrients for blackberry bushes.

If you’d like to buy fertilizer, I recommend the brand Down to Earth. You can see more on my recommended fertilizer page.

You can also make your own blackberry bush fertilizer at home. Here’s a table I put together of the primary nutrients along with the ingredients you can use:

Nutrient	Ingredients
Nitrogen	Coffee grounds, feathers, blood meal
Phosphorus	Bone meal, gelatin, leaves
Potassium	Banana peels, sweet potatoes, mushrooms
Iron	Kelp, beans, spinach
Calcium	Eggshells, bonemeal, molasses

To see my complete list of food scrap ingredients and example combinations, check my post on homemade fruit tree fertilizer.

Soil pH

A blackberry bush could have all the nutrients it requires, but if the soil pH isn’t balanced, the plant won’t be able to absorb them.

This is because a slight acidity dissolves the nutrient solids in the soil and makes them accessible to the plant’s finer roots.

As with most plants, blackberry bushes prefer a slightly acidic soil pH (5.5-6.5).

Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.
Donald Bickelhaupt, SUNY College of Environmental Science and Forestry

The best ways to check your soil’s pH are with pH strips or a meter. I prefer using a pH meter since they’re easy to use and affordable. To see which pH meter I use and recommend, check out my recommended tools page.

If you find your blackberry plant’s soil pH is too acidic (below 5.5), apply alkaline amendments such as wood ash, biochar, or lime.

For soil that’s too alkaline (above 6.5), apply acidic amendments such as sand, peat moss, and coffee grounds.

3. Transplant Shock

If your blackberry bush was recently planted or repotted, and its leaves are starting to curl, yellow, or brown, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.

Avoid transplanting blackberry bushes unless necessary as it can take up to 1 year for recovery.

To help avoid transplant shock, I like to plant with the following steps in mind:

Have the new ground (or pot) prepared
Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
Grab the base of the plant’s stem and wiggle lightly
Using your other hand, scoop up and support the rootball
Lightly place the plant in the new ground (or pot) and fill it in
Make sure the soil is at the same level on the plant as before
Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
Water generously and add more soil as needed

4. Diseases

Root Rot

Root rot, also called Armillaria or Phytophthora Root & Crown Rot, is a root fungus that causes a blackberry bush’s leaves, blossoms, and fruit to droop, yellow, brown, and drop.

This disease typically occurs in areas with poor drainage.

Avoid using sprays for root rot as it’s not effective.

There is no chemical control available for crown and root rot in the home garden. The most important control strategy is careful water management.
Clemson University Cooperative Extension Service

To prevent root rot, only water when the top 2-4 inches of soil is dry and promote well-draining soils.

To treat root rot, transplant your plants to an area with fresh, drier soil. Potted blackberry bushes with root rot should be repotted with fresh potting soil. Raised beds are also helpful in improving soil drainage.

For example, my potted Kaffir lime tree had root rot recently, which I was able to tell from the sopping wet soil and swampy smell. Fortunately, after repotting the tree with fresh potting soil and waiting a few days, the tree made a full recovery!

Cane Blight

Cane blight is a fungal disease that wilts and browns leaves, and kills part or all of a blackberry plant. This usually starts from a wound on the plant, which then spreads to other parts of the plant.

Treat cane blight by promoting airflow and sunlight, and pruning infected canes. Sprays are rarely necessary.

Cane blight survives on blackberry bushes over the winter, so it’s best to prune during cold and dry weather. There are a few ways to dispose of cane blight branches such as composting, but burning is the best method as it prevents cane blight spores from spreading.

How to Fix Brown Leaves on a Blackberry Bush (4 Ways)