Despite not being picky or otherwise finicky plants, hydrangeas do occasionally run into problems like leaves wilting and turning brown.
There are a couple of reasons why this happens, so identifying the underlying cause can be a bit challenging, but nowhere near impossible.
I’m going to cover each possible cause that may be leaving your hydrangea leaves droopy and discolored, focusing on the most common reasons why this happens.
When you bring your hydrangea home from the garden center and immediately transplant it to a pot or even outdoors, the plant may have trouble adjusting to its new environment.
One reason why that happens is the lack of enough moisture. Hydrangeas that are still young and growing, require constantly moist soil until they get established.
Therefore, the lack of enough moisture coupled with a switch from pot to garden can have this effect of leaves wilting and becoming brown.
Before transplanting, it’s a good idea to gently loosen the root ball so that it will uniformly get watered in the new pot or garden.
Water your new hydrangea plant regularly, making sure the soil drains well, so that the roots sit only in moist soil and not soil that is too wet.
Another problem that you may inadvertently cause to your hydrangea is fertilizer toxicity caused by over fertilizing your plant.
While a bit of fertilizer can do wonders for your hydrangeas, leading to more vigorous growth, bigger and more blooms, adding too much fertilizer to the soil can cause toxicity known as fertilizer burn.
Burnt and browning leaves can be symptoms of fertilizer build-up in the soil. This is why it’s important to carefully follow fertilizer dosage recommendations and water the soil thoroughly after each application.
You also need to remember that hydrangeas aren’t heavy feeders, in fact, they can even grow beautifully without fertilizing.
Therefore, use fertilizers that are formulated for hydrangea plants and apply only as directed by the manufacturer.
If a fertilizer requires dilution in water, make sure to add the required amount of water. In fact, you can even make the fertilizer weaker than what’s recommended, just don’t make it stronger by adding less water or more fertilizer.
Slow-release fertilizers may not even require repeat applications. You can use these by working them into the soil when planting the hydrangea.
Depending on the type of fertilizer you’re using, you may only need 2-3 applications per growing season. There are, however, weaker formulations that can be applied every 7-14 days.
Although hydrangeas aren’t prone to pest infestations, on rare occasions you may encounter problems with aphids and scale insects that can leave your hydrangea’s leaves droopy, shriveled up and brown.
When pests invade your plants, turning to pesticides and insecticides must be weighed against the potential damage they may cause to other beneficial insects or organisms on your plant and the environment.
First, I encourage that you try removing pests with more gentle methods such as running a stem of water over the leaves to physically wash off insects.
Alternatively, you can spray the leaves (including their undersides!) with soapy water. The soap coats the insects and causes them to suffocate and die.
You can also use commercially available insecticides or pesticides that have a natural or organic formulation. Only if these fail, should you attempt to use strong chemical pesticides.
If used in excess or in a strong formulation even chemical pesticides can cause browning, wilting leaves, so be careful with them.
Whichever method you use, make sure to use it on a day when rain is not expected and don’t apply it in hot sun.
It’s more likely that you’ll run into fungal diseases than pest problems when growing hydrangeas. Fungal diseases can cause brown spots on the leaves.
There are several reasons why fungal diseases can appear on your hydrangeas:
- Lack of air circulation
- Incorrect watering
- Spread from one branch to another or one plant to another during pruning
To avoid fungal problems in your hydrangeas, you must take a few precautions concerning planting, tidying up, watering and pruning:
- When planting multiple hydrangeas, allow at least six feet between the shrubs. This will improve air circulation, preventing fungal diseases
- When watering hydrangeas, never water from above. Leaves that stay wet for too long can be a breeding ground for fungal diseases. Water only at the base of the plant.
- Cut back dead woods or diseased woods all the way to the base and keep the base of the plant clear of dried leaves and dead stems. This will improve air circulation, cutting down the risk of fungal diseases
- Deadhead hydrangeas at the end of each flowering season to improve air circulation around the leaves
- When pruning hydrangeas sterilize the blades of the pruning shears between each snip to avoid spreading diseases including fungal diseases
These simple steps can heavily reduce the risk of fungal diseases. If a fungal disease is already under way, you may need to remove diseased leaves or branches.
You can also spray the plant with antifungals such as neem oil to reduce the chances of disease spreading. But all things considered, prevention is the best you can do to avoid browning leaves because of fungal diseases.
Exposure to Hot Sun
Circling back to my first cause of hydrangea leaves turning brown — lack of moisture — exposure to hot sun coupled with lack of moisture will also cause browning, scorched leaves.
While some hydrangeas enjoy being in full sun, they only do so if their soil is kept adequately moist. Hot sun coupled with lack of moisture will lead to dehydration, droopy and browning leaves.
Hydrangeas that enjoy only partial sun should not be kept in full sun all day. Their leaves will wilt and turn brown even with adequate watering.
Sooner or later, you may run into leaf discoloration issues with your hydrangeas. Browning leaves are usually a pathological condition or simply a sign that something should be changed in the environment of your hydrangea.
Adequate sun exposure, correct watering and fertilizing, along with proper fungal preventative measures you can avoid most of the problems causing leaves on your hydrangea to turn brown.