Mycorrhizal fungi are a naturally occurring group of organisms.
It is found in the wild attached in a symbiotic relationship with plants. Effectively acting as an extra root system, it enables the plants to extract nutrients and water from the surrounding soil. In exchange, the plant provides the fungi with necessary carbon and sugars. This relationship has been benefitting both parties for millions of years.
This ‘friendly’ fungi also help the plant to develop a strong root system. Which is why we add mycorrhizal fungi to the planting hole when planting trees and shrubs. It is good for all trees and shrubs but we have found it especially beneficial when planting bare-rooted plants such as fruit trees and rose bushes.
Mycorrhizal fungi has been developed for use in gardens, and that made by Rootgrow (you may have seen this in garden centres) is made with UK fungi. It is currently the only plant / soil treatment licensed by the Royal Horticultural Society (RHS).