What Do Mycorrhizal Fungi Do in Fall?

As above-ground growth slows, roots can remain active in autumn while soil conditions are still favourable. Mycorrhizal fungi continue working alongside those roots, helping plants prepare for the colder months ahead.

What Are Mycorrhizal Fungi Doing in Fall/Autumn?

1. Helping roots access nutrients. Their fine fungal threads explore soil beyond the immediate root zone, helping plants access nutrients such as phosphorus.

2. Supporting water uptake. Mycorrhizal networks can help roots access water from a larger volume of soil.

3. Supporting autumn root growth: While soil remains warm enough, many plants continue developing roots even as leaves and shoots slow down.

4. Maintaining the underground network. As temperatures fall, fungal activity gradually slows, but mycorrhizal fungi can persist in roots and soil until conditions improve again.

Why Are They So Important in Autumn?

Autumn can be a demanding transition period for plants. Temperatures are falling, daylight is decreasing, and soil moisture can change quickly.

At the same time, plants are still maintaining roots and preparing for the months ahead.

Mycorrhizal fungi effectively extend the reach of the root system, helping plants explore more soil for water and nutrients without having to produce all that extra root growth themselves.

For mycorrhizal plants, this underground partnership can be especially valuable when growing conditions are becoming less predictable.

How Can You Support Roots in Autumn?

Keep the soil covered. Add an organic mulch to help protect the root zone from rapid changes in temperature and moisture.

Avoid unnecessary digging. Frequent disturbance can break fungal hyphae, damage roots and disrupt soil structure.

Leave healthy roots in the soil where practical. Old roots can contribute to soil structure and organic matter as they gradually break down.

Avoid excessive phosphorus. Very high phosphorus levels can reduce the plant's tendency to form strong mycorrhizal associations.

Support new plants at planting time. When planting compatible plants, apply a mycorrhizal inoculant such as GrowMate RootMax directly around the roots, where the fungi and plant can make contact.

Autumn Is Still Active Underground

Your garden may look quieter, but the root zone is still working.

Protect the soil, minimise disturbance and support the relationship between roots and beneficial fungi now — and you help create a stronger foundation for the next growing season.

***********************************