Key Takeaways

Hydrangeas are one of the most popular perennials thanks to their showy flowers and interesting foliage.
Improper light, sun, soil, water, temperature, or fertilizer—and pests and plant diseases—can damage hydrangeas.
Some conditions that cause hydrangeas to die can be reversed if caught and corrected quickly.

The keys to healthy, showy hydrangeas are well-draining soil, the correct amount of light, water, and nutrients, and providing protection from extreme temperatures. The majority of plant problems are not caused by a disease or an insect but by poor growing conditions, incorrect care, weather extremes, and soggy soil.

However, no matter how much you try, some pests, diseases, and growing conditions can cause hydrangeas to die. With quick intervention, you may be able to reverse the damage to your near-dead hydrangea, revive it, and bring it back to a healthy state.

Here's how.

Check the Soil Moisture Level

Hydrangeas like lots of water, but it is possible to overwater, especially in heavy clay, slow-draining soil. Leaf drop and brown leaf edges are signs that the roots are sitting in water and you are overwatering.

Always check the soil moisture before watering. If the soil is dry about an inch or more deep, it's safe to add more water.

A lack of water can also cause hydrangeas to die. If the leaves are droopy, the plant needs to be watered. Drip irrigation that adds moisture slowly so it is absorbed properly at the root level is a good choice to keep hydrangeas healthy.

Provide Afternoon Shade

Whether your hydrangeas are planted in the garden or in containers, they will grow much better if they receive morning sun and some afternoon shade from the hot sun. Crispy, browning leaves are a sure indication that the plants are getting too much direct sunlight.

Container-grown plants can be moved easily or shaded by an umbrella or covered trellis. Garden plants may need to be transplanted to a better location in the fall when temperatures cool.

Get Rid of Slugs and Snails

Disappearing leaves and leaves with large holes indicate a slug or snail problem in the garden. The pests are particularly fond of new tender hydrangea leaves. Fortunately, slug control is usually simple: hand-remove the pests, kill them with salt, or drown them in a pan of beer.

Improve Air Circulation

Fungal diseases like powdery mildew leave irregular brown patches on hydrangea leaves and flower heads that if left uncorrected can kill the entire plant. Fungal disease damage can often be eliminated by pruning plants to improving the air circulation in and around the shrub.

Always remove the diseased parts of the plant and dispose of them in a plastic bag. Apply a copper fungicide if the problem is widespread.

Flush Away Excess Fertilizer

Hydrangeas thrive in nutrient-rich soil amended by compost or other organic matter. If you choose to use a commercial fertilizer and add too much, you risk burning the root system, which can cause the plant's blooms and leaves to turn brown, droop, and eventually die.

If you've been overzealous with a water-soluble fertilizer, it is possible to still save the plant if you flush the fertilizer out of the soil. When you begin to notice the signs of damage, use a hose to slowly water the plant, giving it more water than normal. The excess water will help move the fertilizer through the soil and away from the root system of your hydrangea.

Reverse Transplant Shock

Whether you are planting a new hydrangea from the garden center or transplanting an established plant to a new location in the garden, it should be done during spring or fall when temperatures are cooler. This gives the plant time to recover without having to suffer through the scorching temperatures of summer.

Whenever a hydrangea is planted or transplanted, expect some leaf wilt. Water the plant deeply at least once a day. Mulch around the plant to preserve soil moisture and continue this watering routine until the wilting stops.

Do not fertilize the plant or prune away the wilted stems because both cause even more stress to the plant.