Mycorrhizae, or mycorrhizal fungi, are fungi which live in symbiosis with plant roots. They embed themselves into the roots of plants and grow hyphae which extend into the soil.

The mycorrhizae feed off carbohydrates from the plant. In return, the plant gets a hugely increased root surface area (ie the root plus the mycorrhizal hyphae) through which it can obtain more water and nutrients.

The implications of this for both horticulture and agriculture could be immense. As well as helping plants obtain more of the vital water and nutrients they need to survive, it could also open up possibilities to grow plants in otherwise inhospitable, dry and nutrient-poor soils.

The mycorrhizal fungi also appear to be tolerant of transplantation, so could improve the growth of, for example, container grown plants when they are planted out.

These clever little fungi are widely available for domestic use, ‘Rootgrow’ is one example of a proprietary brand. Some are for general use, others for specific plant types (eg roses). When using them it’s important to ensure that you follow the instructions carefully, including the volumes to use, and ensuring that the fungi are positioned so they are in contact with the plant’s roots.

As mycorrhizae are usually quite expensive, you may wish to reserve them for particularly important uses. For example, it would be a false economy to use them for temporary bedding plants, however they can be enormously beneficial if you’re planting a tree or hedge which you want to establish quickly.