How to Balance pH for Madagascar Periwinkle

Maintaining the proper pH level is crucial for the healthy growth and vibrant blooms of Madagascar periwinkle (Catharanthus roseus). This article will provide a comprehensive guide on how to balance the pH for this beautiful and versatile plant.

Soil pH Testing

The first step in balancing the pH for Madagascar periwinkle is to test the soil pH. Ideally, the soil should have a pH between 6.0 and 6.5 for optimal growth. If the soil pH is below 6.0, it is considered acidic and will need to be raised.

Raising Soil pH

madagascar periwinkleImage source: Pixabay

To raise the soil pH, you can use the following methods:

Elemental Sulfur

  • Apply elemental sulfur at a rate of 2 to 4 pounds per 100 square feet.
  • Work the sulfur into the top 3 to 6 inches of soil.
  • This method will take 2 to 4 years to achieve the desired pH correction, but the effects can last for several years.

Aluminum Sulfate

  • Apply aluminum sulfate at a rate of 12 to 18 pounds per 100 square feet.
  • Spread the aluminum sulfate on the soil surface and water it in.
  • Overcorrection with aluminum sulfate can lead to aluminum toxicity, so be cautious with the application rate.

Addressing Iron Deficiency

If the soil lacks available iron, you can use iron sulfate-containing fertilizers to correct the issue.

Iron Sulfate Granules

  • Apply iron sulfate granules at a rate of 10 to 14 pounds per 100 square feet.
  • Work the granules into the top 3 to 6 inches of soil.
  • This method will take 2 to 4 years to achieve the desired correction, but the effects can last for several years.
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Iron Sulfate Solution

  • Mix iron sulfate with water at a rate of 2.5 ounces per gallon.
  • Apply the solution to the foliage or soil surface.
  • To prevent damage to the foliage, apply the solution early or late in the day, or on a cloudy day, not in direct sunlight.

Fertilizer Application

madagascar periwinkle 2Image source: Pixabay

For Madagascar periwinkle, a balanced 10-30-20 NPK ratio fertilizer applied at half-strength is ideal. Apply the fertilizer every 2 to 3 weeks during the growing season to promote healthy growth and blooming.

Planting Conditions

Madagascar periwinkle performs best in well-drained soil and sites that receive partial to full sun. Avoid planting in wet, poorly drained soils or in cool spring weather, as the plants may turn yellow-green and struggle.

Conclusion

By following these steps, you can effectively balance the pH and address any iron deficiencies in the soil to ensure the healthy growth and vibrant blooms of your Madagascar periwinkle plants. Remember to test the soil, apply the necessary amendments, and provide the right growing conditions for optimal results.

References

  1. Picture This AI – Catharanthus roseus Care
  2. Iowa State University Extension – Vinca
  3. The Virginian-Pilot – Gardening Q&A
  4. UIC Heritage Garden – Periwinkle (Vinca)
  5. Gardenia.net – Cathranthus roseus (Periwinkle, Vinca)