Phormium Leaves Dying (6 Common Reasons & What To Do)

Phormium is an attractive evergreen shrub. Its sword-shaped leaves come in a variety of colors, including purple, red, yellow, and olive green.

If your phormium leaves are dying, there are several potential causes. These include mealy bugs, poor soil, and overwatering.  In this guide, we’ll take a look at the 6 most common causes and what you can do to deal with them.

Phormium Basics 

Phormium is native to New Zealand. It’s also known as the New Zealand Flax plant. It can be grown in a wide variety of locations and soil types. It’s great for coastal gardens, city gardens, and gravel gardens. It also does well as a container plant. 

Height varies greatly depending on the species. Some varieties provide flowers during the summer, but the focal point of the phormium is always the graceful colorful leaves. 

Phormium is deer-resistant and resistant to rabbits and many other pests. It cannot tolerate harsh winters. It can survive temperatures below freezing for short periods of time but prefers temperatures to remain at 50 degrees or higher. 

It can be grown in zones 7-11. If you wish to grow phormium in a Northern area, simply use it as a container plant. This allows you to bring it inside before cold damage occurs. 

6 Reasons For Phormium Leaves Dying

1. Poor Soil Quality

The phormium can grow in a surprising variety of soil types. However, it does require some nutrients to thrive. The phormium requires nitrogen to grow correctly. 

If there’s a lack of nitrogen in the soil, it can cause the lower leaves to turn yellow or brown. The top leaves will typically be a pale green. The edges of the leaves may turn yellow or brown as well.  Nitrogen is essential for plant growth and photosynthesis. 

Solving Poor Soil Conditions 

The best way to fix poor soil is to have a soil test. This will let you know exactly what your soil requires for optimum phormium growth. Once you know what nutrients are lacking, you can choose a fertilizer that will provide what your plant needs. 

Remove any dead or dying leaves to allow the plant to put on new growth. 

2. Over or Underwatering

Over or underwatering is a common problem for plants. Both can cause the leaves to turn yellow or brown.  The plant can’t bring in water and nutrients if the soil is waterlogged. Overwatering will cause the plant to wilt, and the leaves will begin to die. 

Overwatering can also lead to root rot. Root rot is caused by a waterborne fungus, and is a common problem amongst many plants such as the calathea or areca palm.

Waterlogged soil provides ideal conditions for the fungus to survive. 

Root rot attacks the roots of the plant, causing them to turn brown and mushy. Once they become rotten, the roots can no longer function properly. The plant can’t bring in the nutrients it needs due to the damaged roots. 

Underwatering causes similar conditions. However, when a plant is underwatered, the leaves will become brown and dry or papery. You will also see drooping or wilting. 

Proper Watering for Phormium

You’ll need to water your phormium about once a week. Wait until the top 2 or 3 inches of soil is dry before watering to prevent overwatering. The plant is drought tolerant, so over-watering is much more common than underwatering. 

3. Leaf Spot Disease 

Leaf spot disease is a fungal disease that causes spots on the phormium leaves. It causes brown or gray spots with purple edges. With proper treatment, you may be able to save the plant. However, the disease can spread to other plants, so use caution. 

Treating Leaf Spot Disease

Treat leaf spot disease by removing any infected leaves as soon as you spot them. If many leaves are infected, you may need to remove and burn the plant.

Dispose of any infected leaves by burning to prevent the disease from spreading. 

4. Yellow Leaf Disease

Another disease that commonly strikes phormium is yellow leaf disease. This is caused by a bacteria known as Phytoplasma.

The bacteria causes the leaves to turn yellow or orange. The plant’s growth becomes stunted because the bacteria kills the rhizome. 

Treating Yellow Leaf Disease

Unfortunately, yellow leaf disease is usually fatal for the plant. However, it can spread the disease to other plants.

If it is mild, you may remove and burn any infected leaves.  If your phormium is badly affected, it’s best to remove or burn the plant to prevent the spread of infection. 

5. Frost Damage

Phormium is cold hardy down to 20 degrees. Colder temperatures, or prolonged low temperatures, can cause frost damage. When frost damage occurs, the leaves will turn yellow. They will then turn brown and mushy due to tissue damage. 

Healing Frost Damage

To heal frost damage, you’ll need to prune away any dead leaves. If the temperatures are consistently at or below 20 degrees, cover the plant with plastic or bring it inside. 

You can also help the plant by binding the leaves upright. This relieves the weight off the plant, and can help it survive the harsh winter months unscathed. 

6. Mealy Bugs

Mealybugs are the most common pest problem for phormiums. They feed on the plant’s natural sugars and excrete a substance called honeydew. 

Honeydew is sticky and often grows mold as well. The mealybugs themselves are small, white, and soft-bodied. Signs of a mealybug infestation include yellow leaves, leaf dropping, and black mold that grows on honeydew. Females lay eggs on the plant, which looks like a cottony or waxy coating. 

Eradicating Mealy Bugs

A severe mealy bug infestation can severely deform the phormium, stunt its growth, or even kill it over time. One way to eradicate mealy bugs is to release a natural predator. 

The green lacewing bug won’t harm your plants, and loves to eat other insects, including mealy bugs. Horticultural oil works well, but it must come into direct contact with the pests. 

Given their waxy coating and ability to hide, this can be difficult to accomplish. An insecticide, including Safari (dinotefuran) or Flagship (thiamethoxam), can be highly effective. 

Summing It Up 

A phormium’s leaves are its prized feature, so it can be disheartening to see its magnificent leaves dying. The good news is that most causes of phormium leaves dying can be remedied with proper care. 

If your plant isn’t getting the proper nutrients, start with a soil test and then amend the soil. The drought-tolerant phormium can easily be overwatered, so don’t water it more often than once a week. If your phormium succumbs to a fungal or bacterial disease, remove any infected leaves immediately. 

Frost damage can harm the signature leaves. If the temperatures get below 20 degrees, your phormium will need a little help to survive. Lastly, mealy bugs can be voracious, and severely harm your phormium. 

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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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