How to Revive a Yellowing Thuja Hedge: Treatment and Prevention

A thuja hedge, prized for its functionality and aesthetics, may turn yellow due to various reasons. Here’s how to revive it:

Why Thuja is a Preferred Species:

  • Hardy, suitable for various locations.
  • Thrives in containers, balconies, and terraces.
  • Longevity, reaching up to 200 years.
  • Popular for creating hedges due to rapid growth.

Why Is My Cedar Hedge Yellowing?

  1. Improper Watering:
    • Young thuja requires regular watering.
    • Decrease frequency as it grows (once every 2-3 weeks).
    • Natural precipitation may be sufficient in spring and autumn.
  2. Burn Needles from Sun Exposure:
    • Strong sun reflecting off snow in late winter or early spring.
    • Optical phenomenon causes moisture loss, leading to needle burn.
    • Can last one or two winters before serious damage.
  3. Diseases and Pests:
    • Fungal diseases (Gymnosporangium family, downy mildew) and pests.
    • Insects like Parthenolecanium fletcheri can affect thuja.
    • Diseases may cause needle discoloration and drying.

How to Treat a Yellowing Thuja Hedge:

  1. Water According to Age:
    • Young thuja requires more frequent watering.
    • Gradually decrease watering frequency as the plant matures.
  2. Avoid Thickening:
    • Prevent overcrowding of thuja plants in a row.
    • Well-maintained and properly spaced plants resist adversity better.
  3. Shade from Intensive Sun:
    • Shade the south side of the hedge with a screen or covering material.
    • Protects thuja from intense sun rays that can cause moisture loss.
  4. Remove Affected Branches:
    • If fungal diseases or pests are present, remove affected branches.
    • Dispose of infected needles and treat with copper-containing solutions.
  5. Urine Prevention:
    • Dog and cat urine can be detrimental.
    • Plant aromatic herbs (lavender, geranium, peppermint) at the base to repel animals.
  6. Thorough Washing and Stimulant:
    • Wash yellowed areas thoroughly with water.
    • Spray with a growth stimulant to facilitate recovery.

Prevention Tips:

  • Follow proper agricultural cultivation techniques.
  • Avoid thickening of plants in rows.
  • Timely watering and preventive treatments against diseases and pests.
  • Well-maintained plants withstand adversity better.

By addressing the specific causes and following preventive measures, you can revive a yellowing thuja hedge and ensure its continued health and vibrancy.

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