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Why Are My Hydrangea Leaves Turning Brown?

Today, let’s chat about a frequent issue with hydrangeas – their leaves changing color. It’s important to know that leaves can tell us a lot about a plant’s health. By understanding what different leaf appearances mean, we can figure out and fix the problem.

Often, hydrangea leaves turn brown due to reasons like not enough water, too much direct sunlight, hot weather, or dry and windy conditions. Brown leaves can also be a sign of root or stem damage, which might happen because of an injury, soil that’s packed too tightly, or giving the plant too much water or fertilizer.

Underwatering

Hydrangea leaves turning brown

Hydrangea leaves turn brown because of underwatering.

Hydrangeas really love water, and even a short dry spell can affect their leaves. If it hasn’t been too sunny, you might just see the leaves droop. However, strong sun can dry out the leaves fast, causing them to turn brown.

This usually happens during the hot summer months. But it can also occur in spring, especially if your hydrangea is in a pot. On windy and warm days, the soil in containers dries out really quickly.

Solution:

  1. Check the soil moisture. You can do this by feeling the soil with your fingers or using a moisture meter. If the soil about 2 inches around the roots is dry, it’s time to water the plant.
  2. Water either in the morning or evening. Watering during the hot part of the day might harm the plant.
  3. Aim the water at the ground, not the leaves.
  4. The amount of water should be enough – about 1 to 3 gallons, depending on your hydrangea’s size.

Sunburn

Sunburn

Hydrangea leaves turn brown because of sunburn.

Hydrangeas, especially the Mophead variety, often struggle with too much sun. These types are really sensitive to light and can easily get sunburnt in full sun, leading their leaves to turn dark brown in the summer.

On the other hand, Hydrangea paniculata can handle almost a full day of direct sunlight. So, if you don’t have a shady spot, this type might be your best bet. Most other hydrangea species prefer some shade.

Solution:

  1. Give your hydrangea around 6 hours of direct sunlight daily, and provide shade for the rest of the day.
  2. If your hydrangea gets sunburnt, water it well and create some shade for it.
  3. Next spring, think about moving it to a spot with less direct sunlight.
  4. If your hydrangea is in a pot and gets too much sun, move it to a partially shaded area right away.

Overfertilization

Hydrangea leaves turn brown due to overfertilization

Hydrangea leaves turn brown due to overfertilization.

It’s important to be careful with fertilizing hydrangeas. Sometimes, gardeners use too much fertilizer hoping for bigger blooms. But if there’s too much nutrient concentration, it can actually harm the plant. The leaves might start to burn at the edges, similar to a sunburn, showing dry, light brown edges. Plus, you might see large brownish-maroon spots on the leaves.

Solution:

  1. Water your hydrangea a lot. This helps wash away excess salts from over-fertilization.
  2. Limit fertilizing to just twice per season. Use a slow-release fertilizer made specifically for hydrangeas. It releases nutrients slowly into the soil, reducing the risk of over-fertilization.
  3. The first fertilizer application should be in early spring, before the buds open.
  4. Avoid fertilizing in late autumn and winter, as the plant doesn’t need extra nutrients during these times.

Pests

Mites

Mites

Brown hydrangea leaves without any obvious damage could be due to insects like aphids, mealybugs, and scale. These pests form colonies under the leaves and feed on the plant’s sap. This feeding causes the leaves to turn brown and curl.

Mites deserve a special mention. They’re tiny and only visible with a magnifying glass, but a big colony can really harm your hydrangeas.

Solution:

  1. Spray your hydrangea with horticultural oil.
  2. After a few days, repeat the treatment. This should be enough for your hydrangea to start recovering.

Fungal diseases

Disease

Hydrangea leaves turn brown because of disease.

The two diseases you often see in hydrangeas are Anthracnose and Cercospora leaf spot. With Anthracnose, you’ll notice small light brown spots on the leaves. These spots grow over time, the leaves may turn yellow, and eventually fall off.

Cercospora leaf spot is different. It starts as dark, large spots on the leaves. Then, parts of the leaf may turn brown.

Solution:

  1. Spray your hydrangeas with a fungicide.
  2. Look for fungicides that have Thiophanate-methyl or copper in them.
  3. Keep the area around your hydrangeas free from decaying plants.
  4. Make sure there’s enough space between your shrubs to allow good air flow.
  5. Be careful with watering – avoid both overwatering and underwatering.

Transplant shock

Hydrangea leaves turning brown after transplanting.

Hydrangea leaves turning brown after transplanting.

When you plant hydrangeas in your garden, they might go through transplant shock. This can cause their leaves to turn brown or droop.

The same thing can happen if you move hydrangeas from one spot to another in your garden. Even if you’re really careful, some roots will get damaged, and the hydrangea’s leaves might change color because of this.

Solution:

  1. Give the hydrangea lots of shade, especially right after transplanting.
  2. Water it when the top inch of soil feels dry, but don’t overdo it.
  3. When moving hydrangeas, try your best to keep root damage to a minimum.
  4. To make the soil better, mix in 1-2 buckets of organic material like compost.

Heat stress

Heat stress

Heat stress

Hydrangeas, like many plants, don’t do well in extreme heat. They usually prefer temperatures between 70-80°F. However, if it gets hotter than 90°F on a summer day, your hydrangea might suffer from heat stress.

You’ll notice this if the leaves start drooping and curling, and they might have crisp, light brown edges.

Solution:

  1. If your hydrangea is in a pot, move it to a shady and cooler spot. Or, if it’s planted in the ground, create some shade for it during really hot times.
  2. Water the hydrangea one extra time with a good amount of water.
  3. Next spring, consider moving the hydrangea to a location that’s cooler and doesn’t get as much sun.

Overwatering

Root rot

Hydrangea leaves turning brown because of root rot.

Hydrangeas can handle a bit of dampness, but too much water is trouble. If their roots sit in waterlogged soil, they’ll start to rot. This rot messes up the plant’s inner workings. When this happens, water can’t reach the leaves properly, leading to yellowing and wilting leaves. And if the hydrangea’s been under strong sun, the leaf edges and tips might turn brown.

Solution:

  1. Cut back on watering. Only water your hydrangea when the top 2 inches of soil around the roots feel dry.
  2. If your hydrangea is potted, make sure the pot has holes for drainage.
  3. Shield your hydrangea from harsh afternoon sun with some shade.
  4. Snip off any leaves that look damaged.
  5. Consider moving your hydrangea to a drier spot next spring.

Frost

Hydrangea leaves turning brown because of frost damage

Hydrangea leaves turning brown because of frost damage.

Hydrangeas can get stressed by both cold snaps and intense heat. They’re usually okay with frost, but that’s when they’re dormant. If they’ve already got leaves out, a late frost can hurt them.

Solution:

  1. Start by removing any dead leaves.
  2. Water your hydrangea with a liquid fertilizer, but keep the strength at half of what’s usually recommended.
  3. If frost is in the forecast, cover your hydrangea. There are lots of materials you can use for this.
  4. If your hydrangea is in a pot and there’s a freeze coming, move it inside until the cold passes.

Should I cut off brown hydrangea leaves?

Yes, it’s a good idea to cut off brown hydrangea leaves. It stops the plant from wasting energy trying to save damaged leaves, and it also improves air circulation, which reduces the risk of diseases. Plus, it makes your hydrangea look neater.

Here’s how to do it:

  1. Use clean, sharp pruning shears.
  2. Cut the brown leaf off at the base, near the main stem or branch.
  3. Be careful not to cut too close to the healthy parts.

Remember, it’s also important to figure out why the leaves turned brown in the first place, so you can prevent it from happening again!