If there is one plant that is quintessential to a summer garden, it is the hydrangea. These shrubs practically explode with beautiful flowers throughout the summer. When one of your hydrangeas begins to fail, it can be extremely frustrating. Losing a hydrangea in your garden can cause a huge hole in your foundation plantings or your perennial gardens.
Before you stress too much about what could negatively impact your hydrangea, remember that it most likely has to do with its growing conditions. This makes it easy to revive your shrub by adjusting how you care for your hydrangeas.
Let’s look at 7 reasons your hydrangea may be failing you and what you can do to breathe new life into them.
First, a Bit About Hydrangeas
There are 6 common hydrangea species that we commonly grow in our gardens. These shrubs will bloom throughout the summer and into the early fall. The shrubs have very attractive green leaves that will drop in the winter, leaving the stems barren.
The flowers bloom in a wide range of colors: white, blue, pink, purple, red, and even green. Hydrangeas are native to the southern regions of the United States as well as areas of Asia.
Reason 1: Too Much or Too Little Water
Watering is correctly vital for hydrangea; it requires a perfect balance of sun and the correct amount of water. In general, hydrangeas require one inch of water per week.
This could change depending on your soil type and the species you are growing. Panicle hydrangeas love full sun, and depending on your garden, they may need a little more water.
Symptoms of overwatered hydrangeas may include brown and wilted leaves, yellow leaves that will drop from the plant, and stunted growth. Signs of root rot may present themselves as well. This could appear that half of your plant is dead, and you may see white fungus near the crown of the hydrangea.
Symptoms of underwatered hydrangeas typically show up as brown and dried leaves and flowers, as well as severe wilting that does not easily remedy itself with deep watering.
If your hydrangea is underwatered, this is easy. It is time to up your watering. Place a rain gauge in your garden to ensure that your garden is getting enough rainwater. For people who water by hand or with drip irrigation, a soil moisture meter can help gauge if you need to water again or if things are in good shape. If you have sandy soil, add some compost to the ground to help the soil retain water.
Topping off your gardens with mulch is another great way to help your soil retain moisture. Add your mulch at any time of the year; I prefer to mulch in mid-spring.
If your hydrangea is overwatered, check your soil. Is it muddy? The water may not be draining from your soil quickly enough. Overwatered hydrangeas can struggle with fungal diseases, including root rot which can lead to plant death. Allow your hydrangea time to dry out before you water again.
If you feel that your soil may be too dense for your hydrangea, add compost to your heavy soil to lighten it up. Perlite can also improve drainage when worked through the soil. Another option is to transplant your hydrangea to another location in your garden or to a large container where you can control the moisture a little easier.
Reason 2: Too Much or Too Little Sunlight
Many species of hydrangeas will thrive in partial sun. Panicle hydrangeas, however, love full sun, which is great for gardeners with little shade. However, too much sun and too much shade for hydrangeas can cause some issues.
If your hydrangea is getting too much shade, you may notice smaller flowers or no flowers at all. Other issues could be weakened stems and more fungal growth than normal.
If your hydrangea has been spending too much time in the sun, your plant may look a bit crispy. You may see burned leaves and browned flowers.
If your hydrangeas are growing in the wrong place for too many seasons, it could eventually take quite a toll on your plants, eventually leading to plant loss.
Move your plant!! Seriously though, keep an eye on how much sunlight your plant is getting each day. You can use a sunlight monitor, or set a timer on your phone to check the plant every hour and note if it is basking in the sun or taking a break in the shade.
If you are growing a panicle hydrangea, you are looking for 6 hours or more per day. For any other hydrangea, you are looking for 4-6 hours of sunlight, with the bulk of that in the morning.
If your hydrangea seems to be getting enough light, then sunlight is not what is bugging your plant, and you may need to look deeper into its symptoms.
Transplanting hydrangeas is best done in the spring or the fall because the temperatures are more moderate. In cases where transplanting is needed to rescue your hydrangeas, you can transplant at any time as long as you are committed to keeping your eye on the plant.
Reason 3: Improper Fertilization
Hydrangeas do not need much fertilizer. A spring feeding is usually all it takes to get your hydrangea through the season. Often, the best way to fertilize your hydrangeas is by adding compost to your soil. This magic ingredient adds beautiful nutrients to your soil without any risk of overdoing it.
If you over-fertilize your hydrangeas, you risk burning the root system, which can lead to all sorts of problems. This includes a limitation of blooms. If you have burned your roots, you will notice your plant will begin to brown, droop, and eventually die.
Hydrangeas that may be lacking nutrients could suffer from chlorosis, which is typically caused by a lack of iron. Chlorosis causes your hydrangea leaves to yellow. However, the veins will remain green.
Before you fertilize or add anything to your soil, it is recommended that you do a soil test. These tests will provide plenty of information, and you may find out that your soil may be lacking in one area, or it could be fine without any amending.
If you have recently fertilized your hydrangeas and notice that you used too high of an application rate of water-soluble fertilizer, you can flush the fertilizer out of the soil.
This is a simple process. All it takes is some time and a hose. Slowly water your hydrangea, giving it more water than you normally would. The water helps move the fertilizer through the soil and away from the root system of your plants.
Note that this method only works on water-soluble fertilizers and not on many granular organic fertilizers. However, granular organic fertilizers often are milder on the plants and should not cause fertilizer overdoses.
If your plant is suffering from chlorosis, you can add an iron supplement to the soil, but do so in very small amounts so as to not provide too much. Some composts may also contain iron, but it depends on what the compost is made of.
Reason 4: Heavy Soil
Hydrangeas thrive in well-draining soil. This is soil that retains some water but does not become muddy or very wet around the root system of your plant. If you are unsure how your soil holds water, dig a hole and fill it with water and watch to see how long it takes to drain.
If you know if you have clay soil, don’t worry. Some hydrangeas are not intolerant of heavy soil. Smooth hydrangeas grow very well in clay soil, in fact! As clay soils tend to be surprisingly moisture-retentive, growing hydrangeas in them may just require you to water your hydrangeas a little less.
Hydrangeas become susceptible to root rot if their feet are wet for too long. The unfortunate part of root rot is that it will kill your plant underground before you notice the symptoms above ground. Most root rots are caused by fungi that thrive in cool, damp environments, particularly in the spring or fall.
If your hydrangea has been growing in heavy soil that does not drain well, your root system may be struggling. Roots need oxygen to thrive, and if they are sitting in water for too long, they may begin to rot or die.
The best way to prevent root rot from forming is to plant your hydrangea in well-draining soil to reduce the chances of fungal development. If your soil is not well-draining, it is easy to incorporate compost or other organic material into your soil.
You can do this when you first plant your hydrangeas or alternatively amend it later. I love to add compost to my gardens every year or so. It helps the soil structure while also providing essential nutrients.
Reason 5: Wrong Plant, Wrong Place
A huge reason that plants, including hydrangeas, suffer is that the wrong plant has been planted in the wrong place. This could mean the plant is not getting the correct amount of sunlight.
But a bigger reason is that you have selected a hydrangea that is not correct for your zone. When you are at the garden center, double-check the plant tag to see if it grows well in your zone. If you are unsure, someone at the garden center will be ready to help you. Growing zones indicate the coldest potential temperatures in the winter, so one that does not perform well in your area could become winter-killed.
If you can’t find the right hydrangea for your garden, it may be time to start thinking of a substitute. Do not forget that hydrangeas can be grown in containers and may be overwintered in your garage or shed if you chose one not meant for your winter chill.
Oftentimes planting a hydrangea in a container allows gardeners to move the plants around so they receive the right amount of sunlight. You can also control the soil that your hydrangea is growing in when it is in a container.
Reason 6: Pest Infestations
The good news about hydrangeas and pests is that they don’t have any mortal enemies out there. The bad news is that they are just as likely to get attacked by common garden pests as any other plant in your garden.
I am talking about the usual suspects: Japanese beetles, aphids, slugs, and scale. You get the picture. You may be thinking, “These pests are no big deal.” You’re not wrong. I see these pests every summer in at least one part of my garden. However, if they are left untreated, they may decide to move themselves and their entire families into your hydrangeas.
The black vine weevil is something you should be worried about. These weevils spend their entire plant living in and feasting on every part of your hydrangeas. Like root rot, the worst of the damage happens under the ground, and when you notice the above-ground symptoms, it is likely too late for your hydrangea.
If you have found yourself with an insect issue, using an insecticidal soap is a good way to control most insects.
If you have seen black vine weevils crawling around your plant, you will want to treat your hydrangea with a granular systemic pesticide. This will target the grubs that are munching on your roots and help to stop the life cycle of the weevil in its tracks.
Dusting the leaves and stems of your plant with diatomaceous earth can kill off roaming adults and prevent them from laying more eggs in the soil. Beneficial nematodes applied to the soil will also kill off weevil larvae.
Reason 7: Troubles with Disease
Hydrangeas are resilient plants. However, because they are often growing in the shade, they can be susceptible to fungal diseases. These diseases are spread via moisture, often splashed back onto the plant from the soil, and they thrive in humid and warm areas where the airflow is limited and where the sun doesn’t dry moisture on the leaves and stems.
Signs of fungal diseases on your hydrangea could be irregular spots on your leaves, powdery mildew, brown spots on your flower petals or flower buds, and of course, the dying of a section of your plant or the entire plant.
Prevention is the easiest method here. When you are planting your hydrangeas, make sure you are planting your hydrangeas at the correct spacing. This will allow enough air to circulate throughout your garden, allowing the soil to dry out a bit. Occasional pruning or deadheading to open up the center of your plant also improves airflow.
Keeping your garden free of weeds and plant debris is another great way to keep fungal diseases out of your garden. Infected plant debris may spread fungal spores when raindrops splash around the garden, and the fungi can overwinter in this decomposing material.
Using a copper fungicide is the best option to treat fungal diseases on your hydrangeas. Follow the labeled instructions for application, as each plant and disease differs. Removal of infected parts of your hydrangea is imperative to the plant’s health and the other plants around it.
While some of these situations can be scary to any gardener, it is important to remember that many of the above issues can be easily remedied. This might mean that you need to find a treatment method, such as a fungicide or fertilizer, or you may need to adjust your gardening routine.
The most important thing to remember when adding any new plant to your garden, especially hydrangeas, is that you have chosen the right place for your plant. It is a small and simple thing to do that can benefit your hydrangeas greatly.