4 Reasons Your Hydrangea Leaves Are Turning Brown

Hydrangeas are one of the most popular flowering shrubs. Their blooms are gorgeous, and they’re a low-maintenance plant once established. However, few things ruin the look of a hydrangea shrub faster than the leaves turning brown.

There is a range of reasons why hydrangea leaves turn brown, and most of the time, those brown leaves are a call for help. The good news is you can fix the problem and save the plant if you catch it soon enough. Here's why your hydrangea leaves may be turning brown and what you can do to make your hydrangea happy and healthy again, according to a horticulturist.

1. Too Little Water

Brown edges on the shrub’s leaves could mean your hydrangea is not getting enough water and drying out. “Hydrangeas have very shallow roots, and that's one of the reasons why they are so susceptible to drying out,” says Stacey Hirvela, a horticulturist and marketing manager at Proven Winners.

How much water hydrangeas need depends on the amount of sun the plant gets and the climate it’s growing in, according to Hirvela. “The more sun a hydrangea gets, especially in a warmer climate, the more water it's going to need to avoid turning brown,” she explains.

How to Fix It

Never let the soil around hydrangeas dry out completely during peak blooming season. Apply water as needed to keep the soil consistently moist. Once the plant has been in the ground for two to three years, it’s considered established and will need to be watered two to three times a week, Hirvela advises.

Also, mulch the soil. Hirvela recommends a good two-to-three-inch layer of organic mulch for hydrangeas.

2. Too Much Sun

Brown leaves could mean your hydrangea is getting too much sun. That brown you see on the leaves is leaf scorch. Too much sun also dries out the soil and roots, leading to leaves that turn brown and fall off. Most types of hydrangeas prefer partial shade or filtered light.

Mophead hydrangeas (also called French hydrangeas), the classic type with round flower heads, prefer partial or filtered shade. Panicle hydrangeas, the ones with cone-shaped blooms, tend to be more tolerant of sun than most other types of hydrangeas. They need at least five hours of sun to bloom, and some thrive in full sun.

How to Fix It

Putting the right plant in the right place is key to garden success. For best success, put hydrangeas where they’ll get morning sun and afternoon shade. If you have a shade-loving hydrangea already in the ground and growing in full sun, you may need to move the plant to a shadier spot to stop the leaf browning.

“Hydrangeas are easy to move and quite amenable to moving,” Hirvela says. “That’s the upside of those shallow roots.” She suggests moving a hydrangea in fall or early spring, not the middle of summer. In the meantime, mulch the hydrangea and water it more frequently to slow the leaf damage until you are ready to move it.

3. Frost Damage

Sometimes hydrangea leaves turn brown at the edges because a late spring frost damaged them when they were budding out. “When a hydrangea leafs out in the spring, that new foliage is tender and delicate,” Hirvela remarks. “When winter’s not done and sends another freeze, the cold turns the new growth brown.”

How to Fix It

Your hydrangea likely will recover on its own. “The plant will have another set of auxiliary leaves in reserve that it can put out,” Hirvela says. Your hydrangea may be set back and take some time to recover, but it will be fine.

4. Fungal Disease

If you see brown spots on your hydrangea leaves, your plant may have a fungal infection. Fungal disease shows up on hydrangea leaves as sunken brown spots or black spots. “Fungus thrives in cool, wet conditions,” Hirvela warns. “By the time you see a leaf spot on the foliage, the plant has had the fungal disease for many weeks.” All hydrangeas are susceptible to fungal leaf spots, with oakleaf hydrangeas being the most vulnerable, notes Hirvela.

How to Fix It

Prevention is the best cure for fungal diseases. Good air circulation helps moisture on leaves and stems dry faster so fungi don't get a chance to get established. Don’t place hydrangeas too close to other plants or structures. Trim the lower branches of your hydrangea to allow air to circulate at ground level. Water hydrangeas at the roots so water doesn’t splash on the leaves.

If your hydrangea gets a fungus, don’t spray it with fungicide, Hirvela says. “The best course of action is to clean up all of the foliage at the end of the season. Discard it, don't compost it, and that will disrupt the disease cycle.”

Should I Cut Off Brown Hydrangea Leaves?

If there is a lot of green left on a leaf that’s turning brown, don’t cut it off. According to Hirvela, those brown edges may look homely, but the healthy, green part of the leaf keeps making food for the hydrangea so it can recover from the stress that turned the leaves brown in the first place.

As a rule of thumb, remove leaves when they are 50% or more brown. “Understand that foliage is not going to magically go back to green,” Hirvela explains. “Once it’s brown, it’s done.” Brown leaves will fall off the plant on their own, as the plant allocates its resources to new growth, she adds.