Dahlias(Asteraceae family), known for their stunning blooms, can sometimes disappoint by not flowering. This issue often stems from a lack of adequate sunshine, which is essential for their vibrant growth. Incorrect watering habits, either over or under-watering, can also impede blooming.

Planting at the wrong time disrupts their natural flowering cycle, while insufficient pruning can lead to excessive foliage instead of flowers. Overuse of nitrogen-rich fertilizers and the presence of powdery mildew, a fungal disease, are other common culprits.

In the following sections, we’ll delve deeper into these causes and offer practical tips to rescue your dahlias and restore their splendid blooms.


Dahlia Garden Bloom

Why Are My Dahlias Not Blooming?

Dahlias might not be blooming because of lack of enough sunlight, incorrect watering, or planting at the wrong time. Sometimes, too much nitrogen or a powdery mildew infection might also be responsible.

Dahlias not blooming is a big problem faced by many Dahlia genus plant parents who wait the entire year to see their plant producing gorgeous flowers. Mostly it’s either lack of proper care or external diseases that prevent Dahlias from growing tall and flowering.

Read about all these factors in detail here.

– Lack of Adequate Sunshine

This might be the number one cause behind your Dahlias not blooming in time. See where your Dahlias are being kept in your house. If the Dahlias are being kept indoors away from the windows where they might receive direct sunlight, they will not bloom properly.

Also if the duration of the time that these plants receive direct sunshine is not enough, then their flowering will also be affected.

– Incorrect Watering

Another common reason behind Dahlia buds not opening is the lack of adequate water. If the soil of your Dahlia plant is dry most of the time, then it is being underwatered.

During the growth season, this plant grows quite rapidly and sprouts new leaves and buds every few days. Not providing it with enough water will lead to impeding its bloom.

– Not Planting at the Right Time

Whenever Dahlias are planted in early spring like most other plants, their tubers cannot tolerate the post-cold soil. This is because these plants are native to warm tropical lands and need temperatures above 50 degrees Fahrenheit to grow and reproduce.

Planting in the early season will result in Dahlias not growing tall, less flower production, and even rotting in cases where the soil is particularly wet.

Dahlias Flowers Bloom Issues

– Not Pruning Enough

Deadheading is the process of cutting off the flowers of a plant. Plants produce flowers to make seeds for the next generation. When you cut flowers off, the plant tends to produce more flowers as a compensatory mechanism.

It has often been observed that not deadheading Dahlias tends to slow down their flowering instead.

– Giving Too Much Nitrogen

Too much nitrogen in the soil causes Dahlias to produce lots of healthy leaves, but it might also be responsible for your Dahlias not flowering. More than the usual amount of nitrogen actually suppresses flowering, especially when it is given before the Dahlia bloom season.

The Dahlia plant does need nutrient-rich soil to grow to its full height and produce an exuberant bloom, but if you are fertilizing an already rich soil or using a fertilizer with a high nitrogen content then that spells trouble for your bloom.

You can easily check whether nitrogen is responsible or not by testing your soil. A soil testing kit can be ordered these days and then sent to a laboratory to find out how much nitrogen is present in your soil.

– Powdery Mildew

Powdery mildew is a common fungal infection that almost always leads to Dahlias not sprouting. Although it is not a fatal infection, it might weaken your plant significantly enough to suppress its bloom.

– How to Spot Powdery Mildew

Here are some signs and symptoms that you can observe on your Dahlia plant if it has been infected by this disease:

  • The first sign of a powdery mildew infection is the appearance of tiny, yellow spots on the surface of the leaves. These spots first appear on the upper side of the leaf.
  • As the disease progresses, these spots also enlarge and merge together to form large blotches that might even cover your entire leaf.
  • One tell-tale sign of a mildew infection is that leaves appear to have white powder sprinkled over them.
  • These leaves are unable to carry out photosynthesis and might start falling off.
  • Sometimes, mushroom-like growths emerge from the stem of the affected plant as well.

How To Get Dahlias to Bloom

In order to get Dahlias to bloom with proliferation, provide lots of sunshine and water, plant them later in the season and treat powdery mildew on time.

– Give Them Plenty of Sunshine

Your Dahlia tubers need at least 6 hours of direct sunshine each day starting from the spring season if they are to flower on time. If you live someplace where the sun isn’t strong enough, then this time will extend to about 8 hours.

Of course, it’s best to grow these plants outdoors, but if you are keeping them indoors, then you should always place them near a window.

Additionally, we recommend providing your plants with six to eight hours of direct early morning sunlight. This will give these plants enough mild sunlight without subjecting it to the harsh late-day sunlight.

– Water Them Often

The Dahlia tubers need plenty of water, especially during the flowering period from spring until summer. Water these plants at least two times each week to make them flower. Give water deeply, which means give ample water each time and keep watering until it starts to come out of the drainage hole.

The soil of this plant needs to be kept moist at all times during the warmer months. In order to create a balance between this and overwatering, mulching is a great option. Spread a couple of inches of mulching material on top of the soil to improve the latter’s moisture retention.

Care for Dahlias Flowers

– Don’t Use a Nitrogen Fertilizer on Dahlias Before Bloom

As we said earlier, have your soil tested to see how much nitrogen is already present in it. If adequate levels of nitrogen are already present, then use a fertilizer with a low amount of nitrogen in it.

The N-P-K ratio written on the package of all fertilizers stands for Nitrogen-Phosphorus-Potassium. Choose one that has a low N-P-K ratio such as 5-10-5.

Secondly, do not fertilize right before the bloom period begins. Dahlias tend to bloom from late summer until fall each year.

– Plant in Late Spring

Always plant your Dahlias tubers in late spring when the soil temperature goes above 50 degrees Fahrenheit. Only then will new shoots begin to sprout and grow. As the weather warms further throughout the summer, flowering will start in late summer and last until early fall.

– Treat Powdery Mildew on Time

Powdery mildew is not a particularly damaging infection and will rarely kill a plant, but it needs to be treated early and properly because it will not let your plant produce flowers. It might also be responsible for Dahlias not growing tall.

Given below are some time-tested methods to get rid of powdery mildew:

  • If you want a natural remedy to solve this problem, then neem oil is a fantastic antifungal agent. Soak a cotton roll in neem oil and dab it on the leaves of your Dahlias daily. In a couple of weeks, you will begin to see the white spots fade.
  • Another DIY option is to make a concoction using baking soda with water. Keep in mind that this mixture cannot be applied to the plant daily as it is quite harsh on the plant.
  • You can also get rid of powdery mildew using commercial fungicides. Spray them on the plant as per instructions and see them work their magic in just a couple of days.

– Deadhead Regularly

Make a habit of deadheading some of the flowers as soon as Dahlias start flowering. This sounds counterintuitive but it actually forces your plant to produce more flowers and is a common practice to improve the yield of Dahlia flowers.

Blooming dahlia


Will Dahlias bloom first year from tubers?

It depends on the type of Dahlias and the growing conditions, but generally, Dahlias grown from tubers can bloom in their first year.

Is Epsom salt good for blooming Dahlias?

Epsom salt can be beneficial for Dahlias as it provides magnesium, which is necessary for plant growth, but it may not directly impact blooming.

Can a delayed bloom be a result of overfertilizing Dahlias?

Overfertilizing Dahlias can lead to delayed blooming as it can cause excessive vegetative growth at the expense of flower development.


You now know the various reasons why your Dahlias are not blooming and how to fix them. Let’s quickly summarise this whole guide below.

  • The Dahlia plants will not bloom unless they receive six to eight hours of direct sunlight every day. Don’t place them under a shade and if kept indoors, keep them near the southern side window.
  • A Dahlia plant that is not watered properly will also not produce flowers on time. You should be watering this plant at least two times per week. Water whenever the soil begins to get dry.
  • If you plant Dahlias at the start of spring, they will most definitely not bloom at a time from late summer until fall. Dahlias should always be planted in early summer when the soil temperatures become high enough.
  • Deadheading is very important for the Dahlia tuber plant. People who don’t regularly prune their flowers often begin to see a slowing down in the rate of flowering.
  • Powdery mildew is a common fungal disease that affects the Dahlia plant. It will not kill the plant but will slow down its growth and suppress flowering. Treat it as soon as possible.

There is no doubt that Dahlias produce one of the most delicate flowers out there. If your Dahlias have stopped flowering, you don’t have to worry as you have this handy guide to help you out!

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