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When Do Dahlias Bloom? How Long Does the Season Last?

orange dahlia in full bloom

The dahlia is a tuberous-rooted, showy perennial plant that is native to Mexico. Dahlias are a common garden and household plant for all the right reasons. Not only do they come in a wide variety of colors and sizes, but they’re also easy to maintain.

Plus, they have one of the longest blooming seasons compared to most other garden plants.

If you plant dahlias, it is only natural for you to want them to thrive and look their best. But before anything else, it’s important to understand the plant’s blooming seasons, so you can pull out all the stops and ensure you get beautiful flowers for your garden.

So, when exactly do dahlias bloom? Read on to find out.

garden flower divider

Dahlias At a Glance

Dahlias are members of the Asteraceae or Compositae family, which includes around 32,000 species of plants. This family is also home to other well-known flowers like sunflowers, daisies, chrysanthemums, and zinnias.

Dahlias are herbaceous perennials that can grow anywhere from one to six feet tall, depending on the variety. They have large, showy flower heads that can be as big as ten inches in diameter. Dahlias come in a wide range of colors, including white, yellow, pink, red, and purple.

When Do Dahlias Bloom?

close up yellow dahlia
Image Credit: minka2507, Pixabay

Dahlias typically bloom in late summer or early fall, around August and September. However, the blooming season can start as early as July and last all the way until November in some cases.

The flowers bloom just in time to showcase their beauty before the first frost of the season. Dahlias are known for being one of the longest-blooming perennials, which is just another reason why they’re such a popular plant.

How Long Does the Blooming Season Last?

The blooming season can last anywhere from two to three months. The length of the season will depend on a few factors. Some of these include:


Dahlias prefer warm weather and can tolerate temperatures up to 86 degrees Fahrenheit. However, if the temperature exceeds this, it could cause the flowers to wilt or drop off. That’s why it’s advisable to plant dahlias in an area that gets plenty of sun but is also protected from the extremely hot afternoon rays.

Weather Conditions

Another factor that can affect the blooming season is the weather conditions. If it’s been a particularly rainy summer or fall, your dahlias will bloom later than usual. On the converse, drought conditions with intense heat and minimal rainfall can cause the flowers to bloom earlier than normal in an effort to conserve energy.

Soil Type

The type of soil you have will also play a role in how long your dahlias bloom. For example, if you have clay soil, it tends to retain moisture better than sandy soil. This means your dahlias may not need as much watering, which could, in turn, lengthen the blooming season.

My Dahlias Aren’t Blooming? What Could Be the Problem?

If your dahlias aren’t blooming even during the blooming season, it could be because you’re doing a couple of things wrong. Here are some reasons why your dahlias aren’t blooming and what you can do about it.

Inadequate Sunlight

Dahlias need at least six hours of sunlight each day to bloom properly. If your dahlias are getting less than this, it could be the reason they’re not blooming. Try moving them to a sunnier spot in your garden and see if that makes a difference.

Improper Watering

orange Dahlia flower
Image Credit: Piqsels

You also need to water your dahlias regularly for them to grow into healthy, blooming plants. If you’re not watering them enough, the plants could go into survival mode and focus all their energy on root growth rather than blooming. Make sure you’re giving your plants about an inch of water each week, either through rainfall or manual watering.

Overwatering your dahlias is just as bad as underwatering them.  If the roots are constantly wet, they could start to rot. This will stress the plant and cause it to produce fewer flowers. Water your dahlias only when the top inch of soil is dry to the touch.

Too Much or Too Little Fertilizer

Fertilizing your dahlias is important for their growth, but you need to be careful not to overdo it. If you use too much fertilizer, it could cause the dahlias to produce foliage at the expense of flowers. On the other hand, if you don’t fertilize them enough, the plants will be weak and produce fewer blooms.

It’s best to use a well-balanced fertilizer that’s specifically designed for dahlias. Some good examples include:

  • Dahlia Food
  • Osmocote Plus Outdoor and Indoor
  • Miracle-Gro Water Soluble Bloom Booster Flower Food

You should fertilize your dahlias every two weeks during the growing season. Once the flowers start to bloom, you can cut back to once a month. Be sure to apply it to the soil around the plants every four to six weeks during the growing season.

Insufficient Pruning

pink dahlia
Image Credit: AnnaER, Pixabay

Pruning is an important part of dahlia care, but you need to do it at the right time. Pruning too early in the season can delay flowering. The best time to prune dahlias is after they’ve finished blooming and before new growth begins in spring.

To properly prune, cut the plant down to about 12 inches above the ground. This will encourage new growth and help it produce more flowers. Anything more or less is detrimental to your dahlias blooming.

Pests or Diseases

If your dahlias are affected by pests or diseases, it could also cause them to fail to bloom. Common dahlia pests include aphids, earwigs, slugs, and snails.

Diseases affect normal plant functioning and could lead to your dahlias not blooming. Common diseases here include root rot, powdery mildew, and botrytis blight.

The best way to prevent pests and diseases is to start with healthy dahlias, free of pests and diseases.

garden flower divider

Last Thoughts: Let Your Dahlias Bloom to Their Fullest

Hopefully, you are in a much better position to grow healthy and thriving dahlias. Dahlias are a beautiful addition to any garden, but they can be finicky. By following these tips, you can enjoy beautiful dahlias all season long. Just be sure to give them the care they need, and they’ll reward you with plenty of blooms.

See also: 20 Types of Dahlia Flowers To Grow At Home (With Pictures)

Featured Image Credit: Ralph, Pixabay


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