Root burns in orchids

Root burns in orchids are a common issue in indoor gardening. They are usually caused by improper care, leading to chemical or thermal damage to the root system. Below, we discuss the main causes, symptoms, and treatment options for root burns in orchids.

Main causes of root burns

Excess fertilizer concentration

• High levels of mineral salts can "burn" the roots.
• This often happens when fertilizer dosage exceeds recommendations or when unsuitable fertilizers (high-salt content not designed for orchids) are used.
• Pouring fertilizer on dry roots is particularly harmful. Always water the orchid lightly with clean water before applying fertilizers.

Using hot water

• Water that is too hot can cause thermal burns to the roots.
• This can occur during "warm showers" for orchids if the water temperature exceeds 40–45°c (104–113°f).

Improper use of chemicals

• Applying overly concentrated fungicides, insecticides, or growth stimulants can damage the root tissues.
• Burns may also occur when using high concentrations of hydrogen peroxide, potassium permanganate, or other disinfectant solutions.

Salt buildup in the substrate

• When hard water is used for watering, mineral salts accumulate in the bark and on the roots over time, causing "salt burns."
• This is often visible as white or reddish deposits on the bark and roots.

Symptoms of root burns

Color changes in roots

• Roots may turn brown, black, or yellowish-brown.
• In mild burns, root tips dry out and change color; in severe burns, the entire root system darkens.

Wilted and wrinkled roots

• Healthy roots of most orchids (e.g., phalaenopsis) are covered in a silvery-green velamen layer. Burns damage this tissue, leaving roots wrinkled and "flattened."

Drying of young roots

• Growth tips of roots may "burn out" and stop growing, appearing dry or darkened.

Wilting leaves

• Leaves lose their firmness and appear droopy, especially if the root system is severely damaged and unable to absorb water.

Stunted growth

• The plant stops forming new roots, leaves, or flower spikes, and buds may drop off.

Treatment and recovery of orchids with burned roots

Step 1. Diagnose root condition

• Gently remove the orchid from its pot.
• Examine the roots: remove any dry, blackened, or damaged areas up to healthy tissue.
• Treat cuts with activated charcoal or a fungicide to prevent infection.

Step 2. Adjust watering and fertilization

• Pause fertilization: burned roots need time to recover without aggressive feeding. Avoid fertilizers for at least 3–4 weeks.
• Use soft water: water with filtered or settled water at room temperature (~24–28°c or 75–82°f). Avoid extreme temperature changes to reduce stress on roots.
• Moderate watering: lightly moisten the substrate but avoid overwatering. Damaged roots are prone to rot if exposed to excess moisture.
  • Water by soaking the pot in warm water for 5–10 minutes, only if the roots are not severely damaged or at risk of rotting.

Step 3. Adjust the substrate

• Replace or rinse the old substrate: if salt buildup caused the burns, replace the old bark with fresh substrate or thoroughly rinse the existing bark under warm running water.
• Ensure good aeration: use an airy substrate that does not retain excess moisture. If the substrate is too fine or compacted, roots may experience additional stress.

Step 4. Create favorable recovery conditions

• Optimal temperature and humidity: maintain moderate humidity (50–60%) and a temperature of 20–25°c (68–77°f). Avoid drafts and sudden temperature fluctuations.
• Bright, diffused light: bright indirect light aids photosynthesis and speeds recovery. Avoid direct sunlight, which can overheat the plant and cause further stress.
• Rooting stimulants (if necessary): for severe root damage, carefully use root growth stimulants like "zircon" or "kornevin," strictly following the instructions and avoiding simultaneous use with fertilizers.
  • Overusing stimulants may inhibit plant recovery instead of aiding it.

Preventing root burns

Follow fertilizer dosage guidelines:

• Use fertilizers at half the recommended concentration unless specifically formulated for orchids.
• Always moisten roots with water before applying fertilizer.

Use water at a comfortable temperature:

• Water should not exceed 35–40°c (95–104°f) for "warm showers."
• Test water temperature by touch or use a thermometer.

Avoid spraying hot water:

• Leaves can tolerate slightly warmer water, but roots and aerial roots are more vulnerable.

Regularly replace or rinse substrate:

• With hard water, periodically flush the bark substrate with plenty of warm water.
• Replace the substrate every 2–3 years (for phalaenopsis orchids) or as it decomposes.

Monitor root health:

• Regular inspections (especially for orchids in transparent pots) can help detect early signs of darkening, dryness, or salt deposits on roots.

Summary

Root burns can be chemical (from excessive fertilizers or salt buildup) or thermal (from overly hot water).

Symptoms: darkened or shriveled roots, leaf wilting, or stunted growth.

Treatment: remove damaged roots, treat cuts, replace or rinse the substrate, and adjust care routines.

Prevention: use soft water at the correct temperature, dilute fertilizers properly, and regularly inspect root health.

With proper care and timely intervention, orchids with burned roots can recover and continue to thrive. Careful attention to watering, fertilizing, and environmental conditions is key to maintaining a healthy root system and ensuring your orchid blooms beautifully.