Applying Mycorrhizae to Established Plants

Mycorrhizae are beneficial fungi that form a symbiotic relationship with plants, aiding in nutrient absorption and water uptake. This symbiotic association can significantly enhance plant growth and overall health. Applying mycorrhizae to the soil of a plant that is already growing can be an effective method to improve its performance and resilience.

Key Facts

  1. Choose a living tree: Mycorrhizae need living roots to grow, so select a tree that is already growing.
  2. Create holes around the root ball: Use a pencil or a similar tool to create holes at different depths in and around the root ball of the tree.
  3. Apply mycorrhizae: Pour some mycorrhizae into the holes that you created. Make sure to distribute the mycorrhizae evenly among the holes.
  4. Cover with soil: After applying the mycorrhizae, cover the holes back up with soil. Ensure that the mycorrhizae are well-incorporated into the soil.
  5. Water the tree: After covering the holes with soil, water the tree thoroughly. This will help the mycorrhizae establish contact with the tree’s roots.

Methods of Application

Several methods can be employed to apply mycorrhizae to established plants. The choice of method depends on factors such as the type of plant, soil conditions, and the form of mycorrhizal inoculum.

Direct Application to the Root Ball

This method involves directly applying mycorrhizal inoculum to the root ball of the plant. It is commonly used when transplanting or repotting plants.

  • Create holes or slits in the root ball using a pencil or similar tool.
  • Pour or sprinkle mycorrhizal inoculum into the holes or slits.
  • Cover the holes with soil and water thoroughly to ensure good contact between the mycorrhizae and the roots.

Soil Drench

This method involves applying mycorrhizal inoculum as a soil drench around the base of the plant. It is suitable for established plants in containers or garden beds.

  • Dissolve or mix the mycorrhizal inoculum in water according to the manufacturer’s instructions.
  • Apply the solution to the soil around the plant, ensuring that it reaches the root zone.
  • Water the plant thoroughly to help the mycorrhizae establish contact with the roots.


This method is commonly used for large trees or plants with deep root systems.

  • Create holes in the soil around the plant using a soil injector or similar tool.
  • Inject the mycorrhizal inoculum into the holes.
  • Water the plant thoroughly to promote mycorrhizal colonization.

Foliar Application

While mycorrhizae primarily colonize plant roots, foliar application of mycorrhizal inoculum has been shown to have some benefits.

  • Mix mycorrhizal inoculum with water or a suitable carrier according to the manufacturer’s instructions.
  • Spray the solution onto the leaves of the plant, ensuring thorough coverage.
  • Avoid applying foliar mycorrhizae during hot or sunny conditions to prevent rapid evaporation.

General Considerations

  • Select a mycorrhizal inoculum that is appropriate for the plant species and soil conditions.
  • Follow the manufacturer’s instructions for application rates and methods.
  • Use non-chlorinated water for preparing mycorrhizal solutions.
  • Apply mycorrhizae at the right time of year, typically during the growing season.
  • Avoid applying mycorrhizae in excessively wet or dry soil conditions.
  • Monitor the plant for signs of improved growth and health after mycorrhizal application.


Applying mycorrhizae to the soil of an established plant can be a beneficial practice to enhance plant growth and resilience. By selecting the appropriate method of application and following proper techniques, gardeners and agriculturists can harness the symbiotic relationship between mycorrhizae and plants to improve overall plant performance.



What are mycorrhizae and why are they beneficial for trees?

  • Mycorrhizae are beneficial fungi that form a symbiotic relationship with tree roots, aiding in nutrient absorption and water uptake.
  • They extend the tree’s root system, allowing it to access a larger volume of soil and extract more nutrients and water.
  • Mycorrhizae also help protect trees against pathogens and environmental stresses.

When is the best time to apply mycorrhizae to trees?

  • The best time to apply mycorrhizae to trees is during the growing season, typically in spring or fall.
  • Avoid applying mycorrhizae during hot or dry conditions, as this can stress the tree and hinder mycorrhizal colonization.

How to apply mycorrhizae to trees?

  • Several methods can be used to apply mycorrhizae to trees, including:
    • Direct application to the root ball during planting or transplanting.
    • Soil drench around the base of the tree.
    • Injection into the soil around the tree.
    • Foliar application by spraying mycorrhizal inoculum onto the leaves.

What type of mycorrhizal inoculum should I use for trees?

  • The type of mycorrhizal inoculum suitable for trees depends on the tree species and soil conditions.
  • Ectomycorrhizal fungi are commonly used for trees such as oaks, pines, and birches.
  • Endomycorrhizal fungi are suitable for trees like maples, beeches, and fruit trees.

How much mycorrhizal inoculum should I apply to trees?

  • The recommended application rate of mycorrhizal inoculum varies depending on the product and the size of the tree.
  • Generally, follow the manufacturer’s instructions for the specific mycorrhizal inoculum you are using.

How long does it take for mycorrhizae to colonize tree roots?

  • Mycorrhizal colonization of tree roots can take several weeks to months, depending on factors such as soil conditions, tree species, and the type of mycorrhizal inoculum used.

How do I know if mycorrhizae are successfully colonizing my trees?

  • Signs of successful mycorrhizal colonization include improved tree growth, increased root mass, and enhanced nutrient uptake.
  • You can also check for the presence of mycorrhizal structures, such as fungal hyphae or root tips, on the tree roots.

How often should I apply mycorrhizae to trees?

  • Mycorrhizal fungi can form a long-term symbiotic relationship with trees, so a single application is typically sufficient.
  • However, reapplication may be beneficial in certain situations, such as when trees are transplanted or subjected to stressful conditions.