How to make soil acidic for rhododendrons

Updated November 21, 2016

Rhododendrons are beautiful dark green plants with thick leaves and a wood stem that are found mostly in mountain regions. They bloom in the spring and early summer with a variety of colours including pink and purple. The reason they grow so well in the mountains is because of the high acidic content in the soil due to the decay of leaves, pine needles and other debris. To help your rhododendron grow to its full potential, it is best that you create an acidic soil where your plant will be placed.

Turn your soil with a pitch fork or hoe so that it is not too compact. Rhododendrons like a light airy soil. This is also the best type of soil to promote decay.

Mix organic matter such as leaves, pine needles and bark into the soil. This material will break down over time and release acid into the soil. Rhododendrons are found in areas where there is plenty of decaying material in the soil. Adding organic matter will help to simulate this environment.

Add organic material, from time to time, around the base of the rhododendron so that it can continue to have acid released into the soil. This will act as an acid compost for the plant and provide a rich soil for it to grow in.

Apply a fertiliser with ammonium nitrate to the soil surrounding the rhododendron for a quicker fix. This will lower the pH level and make the soil more acidic.

Treat the soil with an acidifier additive such as Miracid, which is manufactured under the Miracle Gro brand. This is an additive which allows for incremental adjustment of the soil pH for acid loving plants such as rhododendrons, azaleas and gardenias.


Use caution when handling fertiliser and other chemicals. Wear protective clothing including gloves and eye protection.

Things You'll Need

  • Mulch
  • Leaves
  • Bark
  • or Other organic material
  • Acidifier or fertiliser
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About the Author

Keith Dooley has a degree in outdoor education and sports management. He has worked as an assistant athletic director, head coach and assistant coach in various sports including football, softball and golf. Dooley has worked for various websites in the past, contributing instructional articles on a wide variety of topics.