Mycorrhizal fungi – what are they & do I want them?

Autumn and winter are the key tree and shrub planting seasons in the South East of England and gardeners are hearing a lot of references to ‘Mycorrhiza’ so this seems a good time to explore what it/they do.  Mycorrhizal fungi are present naturally in the soil but can be depleted in soil or growing compost that has been deeply dug...