Why Is My Dahlia Wilting? (And What to Do About It)

You walk outside on a hot summer afternoon and suddenly your beautiful dahlia looks completely limp.

The leaves are drooping, the stems look tired, and you start wondering if something is seriously wrong.

Before you panic, here's what to know.

Once temperatures climb into the mid 80s, dahlias start to become stressed. Even if they're getting plenty of water, don't be surprised if you notice the leaves wilting during the hottest part of the afternoon.

Cafe Au Lait plants wilting in the afternoon heat

That doesn't necessarily mean something is wrong.

In many cases, your plants are simply trying to conserve moisture during the hottest part of the day. If they've had enough water, they'll often perk back up once the sun goes down and temperatures cool off.

The same Cafe Au Lait plants later in the evening

First, Check the Soil

If your dahlia is wilting, the first thing to do is check the soil. Stick your finger a few inches into the ground, or use a small trowel to dig down a bit. If the soil is dry several inches below the surface, it's time to water. If the soil is still moist, don't automatically assume your plant needs more water. During a heat wave, dahlias often wilt simply because of the high temperatures, even when they have adequate moisture.

Your job during these hot stretches is simply to help them get through it.

How Much Water Do Dahlias Need?

One of the biggest ways you can help your dahlias survive a heat wave is by making sure they're getting enough water.

I once heard a dahlia expert say that almost every problem with dahlias can be traced back to improper watering. After growing dahlias for years, I have to agree. Paying closer attention to watering, and increasing the amount of water my plants regularly get has made one of the biggest differences in the health and vigor of my plants. Stressed plants will be more susceptible to pests and diseases.

A good rule of thumb is to aim for about one inch of water per week.

That's a great starting point, but during prolonged periods of hot weather, your dahlias will almost certainly need more. Instead of watering on a schedule, pay attention to both the weather and your soil.

Here are a few tips to keep in mind:

Don't Assume Rain Was Enough

A brief summer shower may only wet the surface of the soil.

Before deciding your dahlias don't need water, check the soil a few inches down. If it's dry below the surface, it's time to water.

Water Deeply Instead of Watering Every Day

For dahlias growing in the ground, a deep soaking once or twice a week is much better than a light sprinkle every day.

Deep watering encourages roots to grow farther into the soil, making plants more resilient during hot, dry weather.

Container-Grown Dahlias Need MORE

If you're growing dahlias in pots or containers, they'll dry out much faster than plants growing in the ground.

Once July arrives, container-grown dahlias often need to be watered every day, especially during extended periods of high temperatures.

Does It Matter How You Water?

I installed drip irrigation in my dahlia beds last year, and it's made watering so much easier. In my opinion, drip irrigation is ideal because it is the most water efficient.

But before I had drip irrigation, I watered my field with sprinklers, and that worked just fine!

The important thing isn't how you water.

The important thing is making sure your dahlias receive enough water to get them through the hottest days of summer.

Some Dahlia Varieties Wilt More Than Others

I've also noticed that not all dahlias handle the heat the same way. Some varieties seem much more prone to wilting than others.

Cafe au Lait is probably the biggest offender in my garden. On hot afternoons it can look downright pitiful, even when it's getting enough water. Fortunately, it almost always bounces back once the sun goes down and the temperatures cool.

If your Cafe au Lait starts drooping during a heat wave, don't panic. As long as the soil has adequate moisture, it's often just responding to the heat.

When Should You Worry?

If your dahlias are still wilted the following morning after temperatures have cooled, it's time to investigate further.

Persistent wilting can be a sign that your plant needs water, but it can also point to root damage, disease, or other issues.

Most of the time, though, afternoon wilting during a summer heat wave is completely normal.

Give your dahlias the deep watering they need, let them ride out the hottest part of the day, and they'll often reward you by looking much happier the next morning.

Summer heat can be tough on dahlias, but with consistent watering and a little patience, they'll usually come through just fine.

And before long, your garden will be filled with beautiful blooms.