Why are my Dahlias not blooming? Reasons and Tips to Fix

Due to unfavorable situations, dahlias sometimes do not bloom.    

There can be several reasons for your dahlias not blooming such as inadequate sunshine, underwatering, overwatering, soil composition, lack of pruning, slugs, etc.

Let us look at these reasons briefly and know the signs that can help in the identification of the problem and the respective actions that you can take.

#1) Inadequate Sunshine

Sunshine is one of the most important factors that contribute to the growth of Dahlia.

Dahlia can be tricky when it comes to Sun. Too much or too little can be equally harmful to dahlias.

It will have fewer blooms if it receives more shade and at the same time, too much sunlight can cause a lot of transpiration. A process in which the water evaporates from stem and foliage.


  • In order to reach out to more sunlight, the plant gets taller.
  • There are little to no flowers.
  • Leaves start to wilt and turn brown or yellow

Tips to fix

Dahlias prosper when they have exposure to direct morning sunlight along with filtered sunlight during the hottest part of the days. A blend of light and shade keeps dahlia away from heat stress.  

In hot and humid temperatures a minimum of 6 hours of sunlight is necessary for dahlias to attain flowers.

Whereas in areas where the temperature is lower, a minimum of 8 hours of sunlight is a necessity for Dahlias.

Thus if you see your Dahlia is not receiving enough sunlight, you can prune the branch of the tree that is obstructing its sun.

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#2) Not enough watering

Water is essential for the growth of any flora and fauna. Similarly, Dahlias require enough water so that the soil doesn’t dry up.

You can witness the below signs in dahlias if your Dahlia is under-watered.


  • Leaves and flowers become dry and start to wilt.
  • Leaves turn yellow partly or fully.

Tips to Fix

  • Water your Dahlia in a way that it directly seeps into the roots without wetting the leaves. Keeping the leaves dry can prevent fungal diseases. This facilitates the growth of the plant and helps it blossom.
  • Maintain a strict schedule for Watering. Usually, you would need to water them once or twice a week.
  • You can also add up organic mulch to the soil as it would help to retain the moisture.
  • For commercial farming, drip irrigation is an ideal choice. It is irrigation of water with the help of the tubes focusing on each individual plant.

#3) Overwatering

Dahlias are prone to root/stem rots after the plantation due to soggy and damp soils.

Often this happens in the sprint time as foliage after winter is not much and hence the requirement for water is less.

Overwatering can happen due to two factors

  1. Excess watering
  2. Clay soil with improper drainage


  • Waterlogging around the Dahlia plant
  • Browning of dry leaves on the edge
  • Flowers are brown on the edges
  • Tubers have soft wet areas. You can dig one or two of them to check.
  • Mold growing on the surface of the soil, and stems

Tips to Fix

  • Keep the soil lightly moist but not wet
  • Avoid waterlogging
  • Do not water dahlias more than two times a week
  • Keep proper drainage for Dahlias planted in a pot

#4) Composition of Soil

Soil is the alma mater that nurtures the plant. Its composition, quality, and type are a few of the many deciding factors for a plant’s growth.

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There are 3 factors related to the soil that can affect the growth of Dahlia and blooming.

A. Alkaline Soil

Dahlia thrives in soil that is slightly acidic. The ideal pH value for Dahlia is 6.5. If the soil is alkaline, the Dahlia leaves would start to turn yellow.

Apart from pH value, dahlia also needs well-draining loamy soil.

How to Diagnose?

The yellowing of the leaves is a sign that your soil is not ideal for Dahlia. It is best to test the pH. A reading above 7 means the soil is alkaline.

Corrective Measure

In case you need to bring down the pH of the soil to around 6.5, you can either add aluminum sulfate or sulfur.

B. Nutrient Deficiency

Dahlia leaves may turn yellow due to a lack of nutrients. This could be due to Chlorosis. It signifies that the plant is not able to produce enough chlorophyll.

How to Diagnose?

It can be seen by the yellowing of leaves along with a network of dark green veins.

In case of Nitrogen deficiency, leaves will start turning yellow from the base of the leaf blade. And the old foliage will start to turn yellow first. 

Whereas, in case of Iron deficiency, Dahlia leaves will start to turn yellow from the top of the leaf blade. And the new leaves will be the first to turn yellow. 

Corrective Measure

For Iron deficiency, add iron sulfate to bring up the iron levels in the soil.

For Nitrogen deficiency, apply suitable fertilizer with an NPK ratio of 4 10 10. We would recommend Lilly Miller Bulb & Bloom Food 4-10-10 4lb. You should use a fertilizer with less nitrogen and more potassium.

C. Heavy clay soil

Dahlia requires well-drained loamy soil. Heavier clay soil can lead to waterlogging.

How to Diagnose?

Too much water around the root can obstruct the required nutrients. The initial sign would be yellowing of leaves and if it is not treated timely, your plant may also die.

Heavy clay soil affects drainage. This soil would not dry out as soon as it should and this may result in water logging around the roots.

Corrective Measure

  1. If you notice waterlogging, stop watering until the top 1.5 inches of soil is dry.
  2. Adding a layer of organic mulch will also help.

#5) Pest infestation

Dahlias do not just appeal to humans; animals gorge on them too. Flea beetles, caterpillars, earwigs, slugs, snails, black bean aphids, and thrips love to chug on the leaves of the plant, dismantling the plant’s core strength.

This leads to flower buds rotting even before they open. It can also affect the leaves as they can develop foliar disease and hinder the foliage. 


  • There are small holes on the leaves that appear as spots.
  • Insects are visible on the leaves.
  • Growth disrupted.
  • Leaves are susceptible to losing color and wilt.

Tips to Fix

Caterpillars and snails etc can be plucked out just as they are seen. For slugs, there is the availability of slug baits and pellets as well.

The other bugs like Japanese beetles can be washed off using soapy water. When dahlia is free of these external perils it can induce the swift blooming of the flowers.

#6) Deadheading

Deadheading is the practice of plucking out a dead flower’s head. This helps to keep the competition for resources to a minimum and thus enabling blooming.

It helps in multiple ways as follows.

  1. It beautifies your garden with the removal of dead flowers.
  2. Helps the plant to focus its energy on blooming more flowers.

You can pluck out your flowers when they have faded about 70%.


Dahlia grows large flowers that will add to the beauty of any garden. Thus it would be a great disappointment for any gardener if their Dahlia is not blooming.

Proper care, awareness, and few safety measures can result in the joy of lush dahlias and beautifully healthy.

Below are the factors that can impact the blooming of your Dahlia –

  1. Inadequate sunshine
  2. Underwatering
  3. Overwatering
  4. Soil
  5. Deadheading
  6. Pests
What is the most appropriate time to plant dahlias in order to ensure the flowers bloom?  

Dahlias are summer darlings that can grow and flourish only in hot temperaments courtesy of their natural habitat. They bloom from mid-summer to late fall and the best time to plant them is in late April.