What Causes Hibiscus Root Rot: Cause and Cure

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Root rot in all plants is caused by the fungi, Verticillium and Fusarium oxysporum (Phytophthora genus). It is usually triggered by excessive moisture, so poor drainage or overwatering can cause root rot to develop. 

When fungal growth begins to grow on a plant’s roots, it interferes with the uptake of nutrients and water. This can cause the plant to appear underwatered, but the problem is really that it simply cannot absorb moisture in the soil. 

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This state of affairs can cause well-meaning gardeners to provide more water, which only worsens matters. 

In this article, we will discuss root rot in Hibiscus plants and provide sound information to help you recognize and deal with it. Read on to learn more. 

What Is Root Rot? 

Although the disease is called rot, it is actually a fungal infection caused when cool, moist conditions make it possible for fungi to set up shop and begin growing on and in plant roots. 

When this happens, the roots become dark, soft, and non-functioning. This is deadly to all plants, Hibiscus included, because they need strong, healthy, fungus-free roots to carry oxygen, nutrients, and water to the plant’s body. 

How Do Plants Get Root Rot? 

Most of the time, overwatering is the culprit, but there are other ways the fungus that causes root rot can be introduced to your garden. 

  • It may get a foothold if your plants are too close together and don’t have good airflow between them. 
  • It may develop in piles of wet, moldy leaves and other garden debris. 
  • You may bring it in when you introduce new plants to the garden. 

Any one of these circumstances (or several combined) can set your plant(s) up to develop root rot. 

Incidentally, overwatering, overcrowding, gathering garden debris, and introducing plants to your collection without a quarantine period are also excellent ways to pave the way for many other sorts of diseases and insect pests.

How Can You Tell If Your Hibiscus Has Root Rot? 

To detect root rot before it kills your plant, you must be vigilant. Keep a close eye on your plant and watch for symptoms such as: 

  • Wilted/fallen leaves: If the leaves wilt and fall, even though your plant is well-watered, root rot could be the culprit.
  • Yellowed leaves: Excessive yellowing of leaves on one side or throughout the plant may indicate root rot. 
  • Bud drop: If your Hibiscus drops buds before they have a chance to develop or open, root rot may be the problem.
  • Dark lower stems: In advanced cases, the plant’s stem may be dark brown or black just above the soil’s surface. If you scrape off the bark, you’ll find that the wood inside is also brown or black. This is a sure sign of root rot. 

How Can You Treat Root Rot In Hibiscus? 

If you notice potential root rot symptoms in Hibiscus very early, you can treat the problem by pruning off affected limbs and roots. This means unpotting or digging up the affected plant and examining its roots for signs of rot. 

If you find brown/black mushy roots, you must prune them off completely, well above the point at which the rot begins. You should also prune off wilted, damaged limbs and foliage. Remember to use very sharp, sterile pruning tools. 

Treat the soil with a systemic fungicide for plants in the landscape before replanting the Hibiscus. For potted plants, use entirely fresh potting soil in a brand-new or thoroughly sterilized container. Water with a systemic fungicide immediately. 

You may wish to give the plant growth enhancer treatment when replanting it. This may help it ward off fungal infection. 

As your plant recovers, keep it consistently watered, but take great care not to overwater. 

How Can You Prevent Root Rot In Hibiscus? 

It is much easier to prevent root rot than treat it. To avoid the development of root rot in your Hibiscus plants, you must:

  • Provide consistent warmth. Fungus is spurred to grow in cool, damp conditions. 
  • Always use a sharp, sterilized cutting implement to prune and deadhead. 
  • Prune away damaged or diseased foliage and dispose of it frequently.
  • Space your plants correctly to allow room for growth and airflow. 
  • Sterilize all of your gardening tools and containers before using them. 
  • Amend soil with a systemic fungicide at the time of planting. 
  • Protect outdoor plants against heavy, extended rains. 
  • Provide a systemic fungicide treatment seasonally. 
  • Adopt the soak-and-dry watering method. 
  • Deadhead spent flowers promptly.

Be sure to choose the right Hibiscus variety for your setting. Remember that Tropical Hibiscus is only winter hardy in USDA hardiness zones 9 and higher. It does not do well in cool, damp areas. 

There are wide varieties of hardy Hibiscus that are native to cool and even swampy areas. These make a better choice in the northern United States. 

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