Fungi are some of the most important organisms in our gardens, partnering with plant roots to help them access nutrients, processing dead material and nurturing countless vital processes – but most of the time they are completely invisible to the naked eye. In this episode we meet fungi expert and author of the bestselling book Entangled Life, Merlin Sheldrake, to find out more about these extraordinary organisms.

Do you have a gardening question you'd like Alan Titchmarsh's help with? Submit your question in the comments below or go to www.gardenersworld.com/podcast/questions/

Alan will answer a selection in the Ask Alan podcast series from BBC Gardeners' World Magazine in February and March.

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