Hydrangeas with large, blowing flowers may look their best on hot, hot, and humid days, but they are also susceptible to wilting.
Dehydration and heat exhaustion can occur due to hot weather, just like it does for us.
The dog days of summer will torment them regardless of where they are planted: in a pot or a garden bed.
Dehydration is the primary cause of Hydrangea wilting in hot weather. Water is lost through their leaves, but it can be replaced by giving them deep waterings regularly. Keeping them standing will be easier if you plan and give them good mulch, the right kind of food, and physical structures.
Before we can fix a wilted Hydrangea, we must understand how its biology causes the problem.
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Why Do Hydrangea Wilt on A Hot Summer Day?
Hydrangeas wilt in the heat because they have lost water content in their leaves.
Leaves and stems contain large amounts of water, which contributes significantly to the plant’s physical structure.
Plump, full cells are rigid, like an overstuffed pillow, and they aid in keeping foliage crisp and blossoms aloft. It’s known as turgor because of this internal pressure.
Once that water is gone, the cells droop and lose their elasticity. As a result, the leaves curl or hang down, and the whole plant looks sad and wilted.
As with many seemingly straightforward solutions, there’s more to it than meets the eye. You’ll be able to stop dehydration faster if you know what causes it.
What is Transpiration?
Sweating helps us cool down by allowing the moisture on our skin to evaporate.
Similarly, Hydrangeas use transpiration to move water from the soil to the leaves to stay cool during the summer.
They allow evaporation that prevents the leaves from overheating by opening up the pores of their leaves. As a result, moisture evaporates more quickly in hot weather.
It’s called transpiration, an essential part of plant biology.
Additionally, it aids in efficiently transporting soil minerals and gas from above, as well as preserving leaf turgor by refilling the water available to cells.
Respiration
Photosynthesis is commonly understood as the process by which plants convert light, air, and water into sugar, but this is only half the story.
The process of using sugars to make energy is called respiration. To do this, the Hydrangea must maintain open pores to release oxygen into the atmosphere.
Respiration promotes transpiration. With each inhalation, water is drained from these open pores.
This is especially true during the hottest months of the year when the soil loses more water than can be reclaimed. Dehydration and limpness set in quickly on the leaves.
Soil Evaporation
The condition of the soil is the final piece of the puzzle in figuring out why a Hydrangea becomes dehydrated in hot weather.
Soil that is moist but not wet is ideal for these large-blooming beauties.
Hot weather makes it challenging to maintain that equilibrium.
If the temperature is high, the soil’s moisture evaporates more quickly. It might be too late for the poor Hydrangea to use it before it evaporates.
Plants in pots have limited water supplies, whereas those planted outdoors have to contend with more rapid evaporation rates.
So no matter how you decide to grow yours, keeping the soil moist in hot weather is always a challenge.
Hydrangea Heat Stress Symptoms
Take a look at your Hydrangea if the weather has suddenly warmed up. The following are signs and symptoms of heat exhaustion:
- wilted foliage
- crisp leaves
- scalded leaves
- flower droop
- blossoms turn brown or tan
- petals falling away
Make an extra effort to keep an eye out for Hydrangea plants near walkways or walls.
Heat is reflected from hard surfaces, which can cause the poor plant to be cooked to death.
Heat stress affects potted Hydrangeas much faster than bedded plants. Without the garden’s deep soil, their roots are exposed to higher heat levels.
It’s also essential to think about other things that could make your potted Hydrangeas wilt, especially if they are inside and not in the heat. Here’s my take.
Factors That Exacerbate Wilting In Heat
High Humidity
There are many ways to cool down a plant, but transpiration is one of the most effective.
Unfortunately, transpiration slows down as the relative humidity in the air increases.
As a result, the evaporating moisture has nowhere to go, and the Hydrangea begins to feel the heat.
Please take a moment to think about the difference in comfort we feel between dry and steamy heat. Hydrangeas are no exception.
Soil with Poor Nutrition
Hydrangeas that are undernourished are less able to cope with stressors. Weak stems and thin leaves produce an overall weak plant that lacks strength.
As a result, they lose more moisture more quickly. Hydrangeas in pots that haven’t been appropriately fertilized are more likely to suffer from this condition.
Like a plant with too much nitrogen in its soil, an over-fertilized one is prone to developing scorched leaves.
In hot weather, the Hydrangea loses a lot of nitrogen because it is transpiring faster than it can use it.
It accumulates in the leaves and causes chemical burns. These damaged leaves lose water more quickly and wilt more easily.
Poor Root System
The Hydrangea’s roots are damaged, making it difficult for the plant to draw water from the soil.
Root damage is typical in newly transplanted plants, but pests, disease, and physical damage caused by digging can all play a role.
Finally, if the roots become too hot, they will die, resulting in a cascade of heat-related dieback that can be difficult to detect and treat.
How To Keep Hydrangeas From Wilting In The Heat
Improve Soil Conditions Before You Plant
First, you should improve the soil before planting Hydrangeas in a new bed.
Planting them in the ground may take a little longer, but it will give them a solid foundation for lush foliage and bright blooms.
You can use slow-release fertilizer pellets to improve the soil, but natural materials with a lot of organic material are better.
Before I plant something, I like to mix a lot of well-rotted compost into the soil.
It has a high concentration of organic matter, which helps it retain water and feeds the soil as it decomposes.
It’s OK to use manure and animal bedding if they’ve been allowed to rot for a while.
Also, provide plenty of organic matter for your potted hydrangeas. A potted Hydrangea’s soil mix benefits significantly from including peat moss or coco coir.
This substance not only slowly decomposes to release nutrients but also acts as a sponge, retaining water better than soil alone can.
In addition, it has all the advantages of manure without the unpleasant smell!
Ensure Beds Receive Shade
Providing shade for Hydrangeas as the day progresses can help ease the worst of the summer heat.
They get a good amount of light in the morning, but the heat can get unbearable at noon.
By providing afternoon shade, you’ll give your plants a chance to rest while still providing them with enough light to thrive.
Consider planting taller Hydrangeas on the west side of the bed. As the afternoon progresses, this will provide more and more shade.
Hydrangeas benefit from the shade provided by broad-leaved deciduous plants during the summer, but their leaves fall off in the fall, allowing the plants to thrive.
Hydrangeas that are already in the garden can also benefit from some shade. During the hottest months of the year, I like to use a sun-sail as a temporary shade. (Check Amazon price here)
You can take it off when the season changes, and it gets cooler.
Keeping potted Hydrangeas shaded is as simple as moving them from direct sunlight to a more shady spot throughout the day.
Mulch Well
For healthy and vibrant Hydrangeas, mulch plays an important role. By acting as a “cover,” the mulch helps keep moisture where it belongs, right where the Hydrangeas need it most: its root system.
Pine chips or sugar cane mulch are good examples of light-colored mulch.
It may seem like a minor consideration when choosing mulch, but pale colors reflect more light and keep the soil cooler.
Cooler soils have a greater capacity to store water. Additionally, it protects the Hydrangea’s roots from heat stress, which helps it survive a heat wave.
Apply a layer three to five inches thick of mulch to the soil.
You can use thicker layers of chunkier mulch blends in hotter regions, which allows the water to seep through the soil up to seven inches.
Watering Hydrangeas In Hot Weather
When it’s scorching, it’s best to water plants in beds in the early morning and at dusk.
This ensures that the Hydrangea has plenty of water to drink when it’s most needed and gives it a chance to replenish lost moisture overnight.
Please ensure the soil or mulch at the base of the plant is wet but not soggy by saturating it with water. Also, take your time and let the water soak in.
During hot weather, potted hydrangeas require more care and frequent watering.
Therefore, I prefer to check mine in the early hours of the morning. That way, it’s simple to refuel them for the new day.
Avoid watering at noon or during the hottest part of the afternoon.
It takes time for the Hydrangea to move that water from the soil to its leaves, and much of it will evaporate.
In addition, spraying leaves can act as a magnifying glass, concentrating sunlight and resulting in sunscald, so refrain from doing so.
Water Hydrangeas Before the Heat Arrives
Make sure to prepare your Hydrangea beds and the soil around them in case of an impending heat wave in your area.
To prepare for an approaching heat wave, soak the beds thoroughly with water at least two to three times the average amount a few days beforehand.
However, even though this is usually a recipe for fungal disease, frequent and heavy watering will replenish the soil’s water supply.
In addition, hydrangea roots penetrate deep into the ground, so soaking the bed brings moisture down to the roots.
Fertilize Hydrangeas
Apply a slow-release fertilizer to Hydrangeas in the spring to help them withstand the summer heat.
Slow-release granules formulated for heavy feeder plants are ideal, with the right balance for these spectacular bloomers. (Check Amazon Price Here)
Before mulching, apply a thin layer to ensure a steady supply of nutrients without overburdening the roots.
However, avoid applying fertilizer right before a heat event. Nitrogen excess in the leaves can result from this.
In addition, heat waves cause enormous amounts of water to move from soil to leaves, and some nitrogen is leached into the air as a byproduct.
The best time to feed the Hydrangea is in the late spring or early summer when the weather is coolest.
Hydrangeas in pots follow the same rules. Fertilizing them at the start of the summer season is the key to their success.
One of the best ways to ensure that the roots of your plants receive essential nutrition is to use a balanced liquid fertilizer.
Add Structures to Support Hydrangeas
Hydrangeas can always use a little extra help, even if you’ve done everything you can. There is a solution for every size and situation.
Tomato Cage
A tomato cage is a wire or cane framework wrapped around the Hydrangea. No matter how the plant leans, it will be held up.
These are best suited to smaller plants, such as those in pots or containers.
Bamboo Stakes
Stakes made of bamboo work well for taller Hydrangeas. You can use many of these to keep your blossoms upright and strong.
Place them close to the plant’s base, but be careful not to damage the roots.
Doing so could leave the Hydrangea vulnerable to infection and dehydrated when the weather changes.
Wooden Trellises
A trellis made of wood is an excellent choice for a long, sprawling bed of Hydrangeas.
Using a trellis that is slightly taller than the plant will ensure that it receives the full support it needs.
In addition, large beds with poor light conditions can benefit greatly from having a Hydrangea placed to the west of the plant, which provides shade and support.
Fences
In the same way, a trellis frames a Hydrangea bed; a fence can provide shade and structure while also drawing attention to the flowers.
Of course, you’ll need to do a little more planning than usual, but you can transform a plain fence into a stunning garden feature with some foresight.
Remember that painting your fence a dark color may cause heat to build up, negating many of the advantages a fence provides.
Can Hydrangeas Grow In Hot Weather?
Most Hydrangea varieties dislike hot weather. As the weather stresses their biology, their growth will eventually halt.
However, some Hydrangea varieties are better able to withstand the heat than others.
For those who’ve planted a hot-weather specialist like the adaptable Panicle Hydrangea (Hydrangea paniculata), you may find that it continues to flourish and grow even in the hottest of conditions!
If you provide the proper care and support, your Hydrangeas will be well-positioned to thrive in any climate.
They’ll succeed if you give them plenty of water, well-prepared soil, and appropriate shade.
How to Prevent Fix Wilting Hydrangeas
- Water twice a day, in the morning and early evening.
- Water thoroughly in advance for severe weather forecasts.
- Cover the area with a thick layer of light-colored mulch.
- Fertilize appropriately in the early summer before the heat hits.
- In the afternoon, provide shade.
- Consider the structural elements.