Hydrangeas are those plants that hold out as a staple of gardens everywhere, despite a growing interest in exotics. They’re not difficult to nurture, have a wide range, and are somewhat hardy.
But there are times when a pried hydrangea can fall ill or suffer misfortune. One of the most common signs that your plant has problems is browning on the leaves or flowers.
Why Is My Hydrangea Turning Brown And How To Fix It?
In most cases, browning can be traced back to care issues.
Diagnosing the problem can be a process of elimination, but most problems are easy to fix.
Know Your Hydrangea!
Plants are like people—each one’s unique, and there’s no single rule that covers them all.
This is perhaps most important when it comes to cultivars, which have often been bred to be more resilient to certain diseases or environmental conditions by may be weaker in other areas.
Often, the cause of browning on your plant may not be a matter of poor care, but instead the mistake of meeting the care needs of the wrong plant.
This is why we often have care guides for specific plants and why it’s important to know the species or cultivar names for each of your plants.
We’ll list a few examples of plants that have unusual care needs as we go.
Container Issues
Sometimes, keeping your hydrangea in a container is nice, but this can pose a few additional problems.
In addition to an increased risk of improper watering or Hydrangea fertilizer toxicity, there’s also the issue of actual pot size.
You should repot your plants every 1 to 3 years, depending on their growth rate and nutrient appetite.
You may also need to repot if the plant becomes rootbound.
A rootbound plant has become so cramped that you’ll see roots poking out of the soil or drainage holes, and it can no longer absorb water and nutrients effectively.
This can lead to brown leaves and symptoms similar to malnutrition or dehydration.
When root binding occurs, you’ll want to use a container one size larger than the previous one with adequate drainage holes.
Always use fresh potting soil, as the old soil is likely spent and will be full of toxins.
Fertilizer And Tap Water Toxicity
Even organic fertilizers contain chemical compounds that can harm your plant.
Browning will most often occur due to using too much fertilizer or chemical burns from the fertilizer in direct contact with your plant.
One of the best ways to solve this issue is to use liquid-soluble fertilizers instead of granular, time-release ones.
Time-release fertilizers contain several nutrients, but these will dissolve at different rates, leaving your plant to get a burst of one nutrient but not enough of another.
However, liquid fertilizers will absorb into the soil, spreading out to give even coverage while diluting in a manner that resembles nature more closely.
However, fertilizer isn’t the only chemical compound that can harm your plant.
Tap water coming from municipal lines (or even wells, in many cases) contain toxic chlorine and fluoride gasses, plus several mineral salts which can slowly poison your plant.
If you have to use tap water, let it sit out overnight to allow the gasses to escape, then run it through a filter.
However, a better solution is to use distilled water or natural rainwater.
Lighting
Lighting can be a little tricky if you don’t know your plant.
Most hydrangeas love basking in full sun, but there are some plants, such as the two major categories of Hydrangea macrophylla cultivars:
- Mopheads
- Lacecaps
These cultivars enjoy full sun in the morning or evening but need some protection from the harsh afternoon sun.
Exposure can lead to scorched, browning flowers that need to be deadheaded.
Transplant Shock
Whether you’ve just purchased a hydrangea or need to move it, the plant will suffer transplant shock after relocating it.
Some browning of the leaves may be one of the symptoms, usually in response to trouble absorbing water.
To minimize this problem, gently tease the roots apart before planting so they’ll have an easier time getting moisture from the soil.
Pests And Disease
These two problems tend to go hand-in-hand. Many pests are piercing insects, such as:
- Aphids
- Mealybugs
- Scale
They drink the sap from your plant’s leaves, with some undigested sap ending up in their frass.
Called honeydew, this frass is a perfect breeding ground for common fungal infections such as sooty mold or powdery mildew.
More importantly, excessive feeding can result in brown sports with a yellow halo, making the plant significantly more vulnerable to infections.
These problems may be addressed separately using an insecticide or fungicide.
However, regularly treating your plant to neem soil soaks or neem foliar sprays can tackle both problems while also helping protect your plant from future problems.
Root Rot
This dreaded disease gets its own section because it requires a little surgery to solve.
Root rot can be caused by several bacteria and fungi, although fungal strains tend to be more common.
Early symptoms will resemble overwatering, which is the leading cause of root rot.
However, as the disease spreads, those symptoms will change to resemble underwatering, as the root system can no longer properly absorb water and nutrients from the soil.
Another sign of root rot is that the browning or wilting may begin in one section of the plant, usually on the outside, hunting at the portion of roots that first contract the disease.
To save your dying Hydrangea plant, you’ll need to do the following:
- Excavate the plant and remove all dark brown to black roots with sharp, sterile shears.
- Once you’ve removed the visibly infected roots, dip the remaining root structure in a solution of 1 part bleach to 10 parts water for 30 minutes.
- Air dry the roots for 2 to 3 days.
- While waiting, destroy or sterilize any soil the plant was in to ensure no traces of root rot are left.
- Replant your hydrangea in a new container or back into your garden, giving it fresh soil and light watering to help it settle in.
- Avoid using fertilizer for about 2 months, so it has time to recover.
Watering
Improper watering habits are the most common cause of plant issues, including browning leaves.
Underwatering will cause the leaves to become crispy and start browning from the margins, not to mention some browning of the flowers (especially in Hydrangea paniculata cultivars).
Meanwhile, overwatering can make Hydrangea leaves droop and feel soggy, usually with the brown starting from the inside and working out or appearing in splotches.
The soak-and-dry method works well for this plant, even when growing in your garden.
Simply stick your finger in the soil to see how dry it is.
The exact depth will vary based on your cultivar, but the general rule is to water a hydrangea when it becomes dry 2″ to 4” inches down.
Go slowly and thoroughly, applying the water to the ground around your plant instead of watering it overhead.
This reduces the risk of sunburn and fungal infections.
You’ll know when to stop watering when the ground can no longer absorb at the same rate you’re pouring to (in the case of potted plants) moisture begins to seep from the drainage holes.