plant biology
Mycorrhizae
Last reviewed 2026-10-04
Mycorrhizae are relationships between certain fungi and plant roots. The fungus receives carbohydrates from the plant, while its fine threads can extend into soil and improve access to water or nutrients in some conditions. The relationship is common in nature, but the benefit varies with the plant, fungus, soil, and environment.
What it means
The fungal threads are called hyphae. In many mycorrhizal relationships, they connect with roots and increase the effective soil volume explored by the plant. Different fungi associate with different groups of plants. Not every plant forms the same type of relationship, and some plants do not rely on mycorrhizae in the same way.
How it affects the garden
Healthy soil structure, living roots, and moderate fertilizer use can support soil organisms. Avoid treating a purchased inoculant as a substitute for suitable light, water, drainage, or nutrients. High available phosphorus can change whether a plant benefits, and disturbance can reduce fungal networks.
When planting, handle roots gently and avoid unnecessary sterilization of outdoor soil. The can I grow this tool helps evaluate site conditions, but it cannot diagnose a fungal relationship from a plant's appearance.
Example
A tree growing in undisturbed soil may have an established root and fungal network. Moving it into sterile, heavily disturbed soil changes that environment, but adding a product does not guarantee the same association will form.
Common confusion
Mycorrhizae are not a fertilizer and are not automatically beneficial in every container or field condition. They are living relationships, not a universal plant supplement.
Sources
University of Minnesota Extension explains mycorrhizal associations and their limits in garden soils.
