Three basic ways
Dry powders are the simplest way to use mycorrhizae. Microbes will ‘hibernate’ when conditions get too dry. This is a very stable and durable form of the organisms. They can be applied to the planting hole directly to the root system. This is the most effective means of applying mycorrhizae. However, there is a way to use dry powders on established plantings. Spread the powders under the plant to be treated and lay much on top. Over time the roots will grow up into he mulch and inoculate the roots.
Root Dips are mycorrhizae suspended in a super absorbent gel which glues the mycorrhizae to the roots before planting. Root Dips will not work for established trees and shrubs.
Liquids are great for established plants because the water can carry the microbes down into the soil without digging. The two primary ways to apply is to inject it into the soil or pour it over the top to soak in. Using a root feeder will be necessary to inject the liquid. It is the best method for compacted soils as it will put the microbes directly in the right place in the root zone. When pouring over the top be sure to water the soil very well. Dry soils will keep the liquid on top of the soil too long. Wet soils will soak up the liquid like a sponge.
Remember to keep it simple. Be sure that the microbes get out of the sunlight. They’ve evolved to be underground. Ultraviolet light will kill them. So remember to cover them up with much or make sure they get watered in.
Remember to keep it simple. Be sure that the microbes get out of the sunlight. They've evolved to be underground.