Why Are My Polka Dot Plant Leaves Completely White? (Causes & Treatment)

Hypoestes phyllostachya, the polka dot plant, is a hardy indoor plant native to South Africa, Madagascar, and Asia. Its most common variety has beautiful foliage with pink and green dots. Unfortunately, polka dot plants are also vulnerable to fungi which can turn their beautiful leaves white.

Powdery mildew is the reason your polka dot plant leaves turn completely white. Powdery white mildew is a contagious fungal disease affecting indoor and outdoor plants. It starts as powdery spots and spreads quickly to cover the whole plant making it completely white.

The beauty created by the polka dot plant varieties makes them perfect houseplants and groundcovers. I’ll explain how powdery white mildew fungal disease affects polka dot plants and how you should care for them.

What Causes White Leaves on Polka Dot Plants?

Polka dot plants are heavy feeders, meaning they need a lot of watering, especially indoors. They also need lots of nutrients to become the leafy plants you want indoors. But there’s one risk here.

Powdery mildew causes white leaves on polka dot plants. This discoloration is due to conditions such as poor ventilation, overwatering, and low light which enables fungal mildew to thrive. Overly saturated potting soil is also a perfect condition for promoting mildew growth.

What Is Powdery Mildew?

Like animals, plants are susceptible to pests and diseases, whether indoor or outdoor. Knowing what’s ailing your plants is one thing and learning how to deal with it is another. Caring for your plants can extend their lifespan, giving your home a leafy look.

Powdery mildew is a fungal disease that manifests as a white fuzzy mold on foliage and stems of indoor and outdoor plants. By covering plant leaves, the mold makes photosynthesis difficult for plants, weakening them and causing them to die over time.

Read: Polka Dot Plant Leaves Curling

How To Cure Your Polka Dot Plant’s White Leaves

Whether you’re managing a few potted plants or a garden, your plants are always at the risk of pests and diseases. The difference comes in how you care for them.

Use Mouthwash

Ethanol-based mouthwash could be an effective remedy against powdery mildew. Mix one unit of mouthwash with three water units and apply the solution to the affected plants. Avoid overdoing it and using it on new plant growths as it can burn the plant’s tender leaves.

Use Vinegar

Vinegar is also effective in removing mold and white spots on plants. Vinegar is mildly acidic with a pH of between 2-3. Misting the affected plants with diluted vinegar lowers the pH below the optimum where the fungi spores can’t reproduce, stopping the spread.

  1. Mix 2-3 tablespoons of vinegar with two pints (1.13 liters) of water.
  2. Spray the diluted solution on the affected leaves and stems.
  3. Repeat the process for several days until the white mildew is gone.

Try Neem Oil

Neem oil is an organic insecticide effective at killing bugs on indoor plants. You can also use it to prevent powdery mildew on polka dot plants.

  1. Mix 2-3 teaspoons of neem oil with four pints (2.3 liters) of water and put the solution in a sprayer.
  2. Spray the affected parts for a few days, and check the white mold quantity on the plants.
  3. Repeat this until the mildew is gone.

How Powdery Mildew Develops on Plants

Powdery mildew affects various plants. These fungi need hosts to grow and complete their life cycle. Therefore, they’ll infect healthy plants. Some of these fungi have a wide range of hosts, while others are host-specific.

Therefore, you might find that the fungi troubling your polka dot plants aren’t the same as those in your host plants’ garden.

Powdery Mildew Life Cycle

Powdery mildew has a simple life cycle on most host plants. Their spores develop in chains on plant stalks. Wind and air currents disseminate these pores to land on other plants and surfaces. On their new hosts, they germinate and pierce the host plant epidermal cells with their food-seeking projections.

The spores multiply, forming strands of fungus over the host plant, and as more spores form, the plant begins to turn white completely. Seventy-two hours is enough for new spores to form upon landing on their new host but typically takes 5-7days.

Unlike most fungi, powdery mildew doesn’t require free moisture on the plant to penetrate the epidermal layer and infect. The spores can thrive even when the humidity is low, so you must be careful when it affects your polka dot plants. You might think holding back watering will prevent powdery mildew, but it will continue to spread.

How Powdery Mildew Survives Through Winter

Powdery mildew will create dark round resting structures called chasmothecia. These resting structures protect the spores during winter and later release them when the conditions are conducive.

Powdery mildew has developed ingenious ways to survive. So, it would help if you got rid of it at whatever cost. Otherwise, it will infect your polka dot plants throughout the seasons. In areas like Minnesota, powdery mildew can survive on plants that remain green during winter, especially greenhouse plants.

Powdery mildew development depends on several environmental factors, including:

  • Air circulation
  • Temperature
  • Lighting
  • Relative humidity.

The conditions become conducive for powdery mildew development in mid to late summer. Therefore, powdery mildew outbreaks become rampant during this time. Because of its timing and cosmetic nature, powdery mildew doesn’t have lasting implications on woody or herbaceous plants. But there will be no respite for your polka dot plants.

Their ground-covering nature means they create perfect conditions for the growth and development of powdery mildew. Therefore, it would be best to learn how to protect your polka dot plants from this fungal infection.

Check: How To Make My Polka Dot Plant Bushy?

How To Prevent White Mold on Your Polka Dot Plants

It’s pretty easy to take care of polka dot plants indoors and outdoors, but with an exception. Avoid overwatering outdoor ones – they are exposed to the wet conditions outside and may not require as much water as in a controlled indoor environment.

Polka dot plants thrive in US Hardiness Zones 10 and 11, such as  Southern Florida, California, and Hawaii. In the latter, they tend to grow for a long time before expanding in the following season.

Ensuring your polka plant is healthy will prevent conditions such as powdery mildew and white leaves. You should provide for your polka plant’s unique requirements as follows.

Provide Adequate Soil Conditions for Polka Plants

Polka plants in the garden thrive well in compost and peat moss. They do well in peat moss in a flowerpot because of adequate drainage. And they may lose their color if you grow them in inappropriate soils. Also, waterlogging can cause their roots to rot.

Try to improve the soil you have around. You can try using fertilizers to provide supplemental nutrients to your polka plants. However, avoid putting too much fertilizer as it will damage them.

Other ways you can prevent conditions such as white leaves are as follows:

Water Your Polka Plants Adequately

Polka plants shouldn’t be overwatered or underwatered, or they’ll lose color. Underwatering polka plants deprive them of vital nutrient uptake, causing them to lose color.

Overwatering means the soil is soaked or soggy. The roots are the first to suffer and manifest by the plants losing color and becoming leggy. You should also avoid using hard water as it could be harmful considering its high mineral content.

What about buying a soil moisture meter or soil hygrometer? It will help you with a numerical reading of the soil’s moisture content to know when to quench your plants and when to hold off watering.

You can try this XLUX Soil Moisture Meter I found on Amazon.com. It comes with highly-accurate sensing probes for reliable measurements. It’s ideal for both outdoor and indoor use.

Provide Adequate Lighting

Most polka plant varieties thrive well in plenty of indirect sunlight. However, If you grow them indoors, they get low-intensity sunlight and could lose color. And when you grow them outdoors, direct sunlight may damage their foliage.

The solution is to give them the brightest indirect sunlight. Choose a spot on an east-facing window where they’ll receive less intense morning sunlight. Watch their color cues throughout the seasons and adjust their positions accordingly.

Pruning Your Polka Plant

Pruning is essential to get rid of the sick parts of a plant and keep the plants in good shape. It would help if you pruned excess foliage of your polka plants to allow for free air circulation, preventing powdery mildew development.

Excess foliage and plants compete for the available nutrients, so you should remove excess polkas from the garden or containers.

Final Thoughts

Polka dot plants are beautiful indoor and outdoor plants that can fill your home with life, but you must consider that they are sensitive to low and excess soil moisture content.

They will develop powdery mildew if kept under moist conditions, causing them to turn white or even die if unchecked. So it would help if you kept an eye on their health, and they’ll beautify your home the way you’ll like them to.

You may like more: