Zinnia Leaves Turning Yellow: 9 Reasons With Solutions

Zinnia leaves turning yellow are a lot more common than you would expect.

It can happen for several reasons, such as overwatering, underwatering, and lack of sunlight, and can indicate stress.

It’s important to get to the root of the problem to help your zinnias bloom all summer, so keep reading to learn nine reasons why this can happen and what you can do about it.

9 Reasons For Zinnia Leaves Turning Yellow

Let’s get straight into the list.

1. Overwatering

Overwatering is a common cause of zinnia leaves turning yellow.

When you provide too much water to your zinnias, their roots can’t breathe properly and may suffocate, leading to a lack of essential nutrients being absorbed by the plant.

Overwatering can, in severe cases, lead to root rot as well. Both types of overwatering will affect the leaves and cause them to turn yellow and slowly die.


To address this issue, you’ll need to adjust your watering practices. Here are some steps you can follow to help save your overwatered zinnias:

  1. Check the soil moisture: Before watering your zinnias, always stick your finger about an inch into the soil. If the soil feels wet, refrain from watering for another few days.
  2. Improve drainage: Make sure your zinnias are planted in well-draining soil.
  3. Water less frequently: Zinnias generally prefer consistent moisture, but it’s important not to overdo it. Allow the soil to dry out slightly before watering again. This helps prevent root rot and other issues caused by overly wet soil.
  4. Monitor the weather: Adjust your watering schedule during rainy periods to avoid drowning your zinnias.

By following these steps, you can help bring your zinnias back to a healthy state and prevent further issues caused by overwatering.

2. Underwatering

Underwatering is one of the common culprits behind zinnia leaves turning yellow. When your zinnias receive inadequate water, they cannot absorb essential nutrients, which can result in the yellowing of the leaves.

The lack of moisture can also lead to dry and wilted leaves, further affecting the health and appearance of your zinnia plants.


Finding the right balance in watering your zinnias is crucial to address underwatering.

Start by ensuring your zinnias are planted in well-draining soil, which helps avoid waterlogged roots while providing sufficient moisture for the plants. If you’re growing zinnias in containers, ensure the pots have proper drainage holes and avoid letting excess water accumulate in saucers.

Here are some helpful tips to prevent underwatering your zinnias:

  • Monitor soil moisture regularly: It’s important to check the soil’s moisture levels around your zinnias to determine whether they need watering. Use your finger or a moisture meter to gauge the soil’s moisture content up to a 1-inch depth from the surface. If the soil feels dry, it’s time to water your zinnias.
  • Water early in the day: Watering your zinnias early in the morning helps prevent the rapid evaporation of water and allows the plants to utilize the moisture effectively throughout the day. Avoid watering during the hottest part of the day or late in the evening, as this can lead to fungal diseases due to excess moisture.
  • Deep, infrequent watering: Instead of frequent shallow watering, opt for deep, less frequent watering sessions. This encourages stronger and deeper root growth, allowing your zinnias to access water from deeper soil layers, promoting healthier growth.

3. Lack Of Sunlight

Zinnia leaves may turn yellow due to a lack of sunlight.

Sunlight is essential for plants to perform photosynthesis, which helps them produce energy and maintain their health. If your zinnia does not receive enough sunlight, it may exhibit yellow leaves as a sign of stress.

A close up of Zinnia flowers in bloom

Zinnias are sun-worshippers, so providing them with enough sunlight is absolutely crucial.


To remedy the lack of sunlight, you can take a few steps:

  1. Relocate the plant: Move your zinnia to a better-lit location where it can receive the full sunlight it needs. Keep an eye on how the sunlight shifts throughout the day and find a suitable spot in your garden or windowsill.
  2. Prune surrounding plants: If other plants or structures are casting shadows on your zinnia, consider trimming them back to allow more sunlight to reach your zinnia.
  3. Rotate the plant: Rotating your zinnia ensures that all sides of the plant receive equal exposure to sunlight, helping it maintain healthy growth and color.

Remember to monitor your zinnia after implementing these solutions. It might take some time for the leaves to regain their green color, but with consistent care and adequate sunlight, your zinnia should thrive again.

4. Poor Draining Soil

One common reason zinnia leaves turn yellow is poor draining soil.

Poor draining soil is not an issue immediately, but when you start to water it, you will quickly realize why it is a problem. Soil with poor drainage is prone to becoming overwatered, which suffocates the roots and causes the leaves to turn yellow and die.


Make sure you plant your zinnias in soil that drains well.

You can purchase a well-draining mix from your local store or use a sandy soil mix with added compost if you prefer to make your own.

5. Aster Leafhoppers

Various pests can cause yellowing zinnia leaves.

One of the most common pests that can lead to yellow leaves is the aster leafhopper, which spreads the aster yellows phytoplasma. This pest feeds on the sap of zinnias, injecting the phytoplasma into the plant’s vascular system and causing flower deformities alongside the yellowing leaves.


To manage aster leafhoppers and prevent the spread of aster yellows:

  • Regularly inspect your zinnias for leafhoppers or any signs of infection.
  • Remove any infected plants promptly to prevent the spread of phytoplasma to healthy plants.
  • Encourage natural predators, such as ladybugs and lacewings, by planting flowers that attract them.
  • Use insecticidal soaps or horticultural oils to control leafhoppers, and follow the product instructions carefully.

You can learn about other zinnia pests in our dedicated article here.

6. Disease

Another reason your zinnia leaves might turn yellow is due to diseases affecting the plant. Several diseases can cause yellowing leaves, including aster yellows and bacterial leaf spot.

White Zinnia flower up close

A zinnia infected by aster yellows may have strange green growths emerging from the flower head. Other symptoms include stunted growth and reddening or yellowing leaves.

Bacterial leaf spot produces unsightly angular, reddish-brown, or dark-brown spots surrounded by a distinctive yellow halo. The leaves become cracked and dry as the spots grow, and the zinnia becomes susceptible to further damage.


To prevent and treat these diseases, try the following steps:

  1. Watering practices: Avoid getting water on zinnia leaves, as this can encourage the growth of fungi and bacteria. Water at the base of the plant and avoid overhead watering.
  2. Air circulation: Keep enough space between your zinnia plants to promote good air circulation, which can help reduce the spread of disease.
  3. Prune infected leaves: Regularly inspect your zinnias for signs of disease and remove any infected leaves to prevent the disease from spreading to healthy parts of the plant.
  4. Fungicides: For diseases like powdery mildew, you might need to use a fungicide to keep the disease under control. Be sure to follow the product instructions for proper application and safety precautions. source

By following these solutions, you can protect your zinnias from common diseases that result in yellowing leaves and enjoy their beautiful blooms throughout the season.

7. Part Of Their Life Cycle

Zinnias are annuals, meaning they complete their life cycle in one growing season.

Zinnias germinate in late spring, bloom during the summer, and then begin to set their seed. After this, they die during the winter.


You can’t keep a zinnia alive when the winter comes around, but you can deadhead the flowers during the blooming months to prolong this period.

8. Nutrient Deficiency

Another reason for your zinnia leaves turning yellow is a nutrient deficiency. Plants require a balance of essential nutrients to thrive, and when they lack one or more of these elements, it can lead to yellowing leaves.

Nitrogen, for example, is responsible mainly for leaf growth and development. It is found in complete fertilizers and the other two main nutrients for plants: phosphorus and potassium.

A bush full of blooming Zinnia flowers

Deficiencies in these nutrients can result in distinct symptoms, but yellowing leaves are a common sign of nutrient imbalance in your zinnia plant.


There are two easy ways to provide nutrients for your zinnias:

  • Add Compost To The Potting Mix – Compost is packed full of nutrients, and this is a super cost-effective way to provide them.
  • Fertilize Monthly – Use a complete fertilizer (one containing all three essential nutrients NPK) once monthly. If you want to encourage blooming, try one with more phosphorus than nitrogen, as phosphorus is important for blooming.

9. Transplanting

Developing zinnia roots do not like to be disturbed, and transplanting can lead to problems down the line, like stunted growth, lack of blooming, and yellowing leaves.


Zinnia flower seeds should be sown into the flower bed rather than grown indoors and then transplanted.

In Summary

Hopefully, this guide has given you insight into why your zinnia leaves are turning yellow and what you need to do.

Zinnias are pretty hardy plants, so as long as you aren’t doing something seriously wrong, you should be able to get them back to health in no time!

Yellowing leaves are a common problem for many outdoor flowers – check out some of our other articles below:

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About Me

Hi, I'm Joe! I'm the head of SEO and content management at Bloom and Bumble. I'm a huge plant lover and over the years my home has become more like an indoor rainforest. It has taken a lot of trial and error to keep my plants healthy and so I'm here to share my knowledge to the rest of the world.

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