Phormium may die due to leaf-yellow disease that’s caused by bacterial pathogen. Leaf-spot disease is also a common reason why Phormium plant dies. A severe mealybug infestation can also kill a New Zealand flax plant.
Phormium tenax is a plant species that is used as an ornamental plant. Phormium tenax is commonly called as the New Zealand Flax plant/Harakeke.
Phormium is grown for its beautiful foliage. It is easy to grow this plant but beginners may experience some hurdles, let’s see what they are and try to find solutions for them!
Why is my Phormium going brown?
Phormium leaves turn brown at the edges when the plant lacks essential elements like Nitrogen. Phormium leaves also turn brown due to Sunburn. A severe mealybug infestation also turns the Phormium leaves brown.
Nitrogen deficiency in Phormium
Phormium plant’s leaves turn brown when the soil doesn’t have adequate Nitrogen in it. This situation is called Leaf margin necrosis.
You can’t help the brown leaves in any way. You can amend the soil to help the future foliage of your New Zealand flax plant.
Add liquid fertilizer like ‘Miraclegro’ or ‘Peter’s’ to the soil to increase Nitrogen quickly. Dilute the fertilizer according to the label instructions.
Tip: Get the soil tested before you amend it!
New Zealand flax plant is drought-resistant, so they don’t need much water to thrive. You just need to water the plant weekly once.
Giving your Phormium more water than it needs leads to waterlogged conditions. Phormium leaves turn brown in such conditions.
Check the soil with your fingers and water only when the top 2-3 inches of the soil is dry. Get a soil moisture meter if possible.
Phormium leaf spot
Leaf-spot disease in Phormium by a fungal pathogen. The infected Phormium plant leaves have brown/greyish spots with purple edges.
Cut off the infected leaves as soon as you spot them. The plant may recover eventually. Get rid of the infected plant to prevent a wide-spread infection.
Mealybug infestation in Phormium
If you see white, waxy substance at the base of the leaves then your New Zealand flax is infested by Mealybugs.
Mealybugs are tiny insect pests that don’t get killed even by winter frosts. They love to feed on the leaves when the weather is warm.
Your New Zealand flax gets stunted as mealybugs feed on the plant. A severe mealybug infestation might kill your Phormium plant.
How to get rid of Phormium Mealybugs?
- Try to get rid of ants around your New Zealand flax plant as they deter the natural enemies of mealybugs.
- Spray water at the place of infestation to get rid of mealybugs naturally.
- Spraying insecticidal soap or horticulture oil on the infested plant works wonders.
- Destroy the plant if the infestation is severe.
Why is my Phormium turning yellow?
Phormium leaves turn yellow because of a bacterial pathogen Phytoplasma. The disease is called leaf-yellow. Phormium leaves may also turn yellow due to frost damage.
Leaf-yellow disease in Phormium
Leaf-yellow disease is caused by a bacterial pathogen called Phytoplasma which is transferred from a diseased plant to a healthy plant by flax plant hopper.
Infected Phormium plant becomes stunted and the rhizome gets killed by the bacteria. Leaves turn orange-yellow in color.
The disease may last for years if not months. Leaves yellow a lot in the growing season. You may want to dig up the plant and burn it to prevent the spread of infection.
Phormium frost damage
Phormium are frost-tolerant up to 20C. If the temperatures fall below this then the plant experiences frost damage.
Frost-damaged plant leaves discolor and become mushy. The plant looks like it’s dead. The plant should come back if you took good care of it.
Cut the dead leaves with a pair of sharp, sterilized pruners. Give your New Zealand flax some time to recover from frost damage.
How do you protect Phormium in winter?
You can protect your Phormium plants from winter damage by reducing the weight of the leaves. Do not let the plant go through winter all alone, help the plant.
Tie up the tuft of leaves to help reduce the weight of the leaves. This helps reduce frost damage considerably as I’ve seen.
Why won’t my Phormium flower?
Phormium flowers when the plant isn’t split. If flowers are important for you then do not split your New Zealand flax plant.
Give your Phormium a dose of Potash in the spring to encourage blossoms. If you decide to split your Phormium do this in dry weather.
Sometimes you just need to give your plant some time to restore its strength. Plants don’t blossom when they don’t have adequate energy/resources.
Happy Gardening 🙂