Question on Mycorrhizal fungi

madpenguin

Does the mycorrhizal fungi always need to be added only when putting a new plant in the soil or can it be dug in (watered in?) around existing plants?

BobTheGardener

It needs to be in direct contact with the roots, so probably only effective when planting.  Thoughts are divided on its effectiveness but all of the shrubs and trees I have used it on are doing well.  I suspect it is most effective when planting in poor soil such as many new builds which may just have subsoil with a thin layer of imported topsoil.  In established borders, the best thing to do is mulch them annuually with well-rotted manure or garden compost as this will produce soil conditions in which the natural mycorrhizal fungi will thrive.

Lyn

Absolutely agree Bob, I’ve never used it and my shrubs and plants are fine.  Only ever put home made compost on my garden. 
I expect tv Gardeners such as Monty Don are told to mention certain garden products for sponsorship and for advertising purposes. 

Hostafan1

I've seen no " double blind " evidence that it has any benefit whatsoever.

Pete.8

There have been trials and the results are inconclusive  - I think Bob's post pretty much sums it up.

Hostafan1

@Pete.8 I've seen that tree growing over the wall. It's in Cambodia

Pete.8

They're mighty impressive!
Reminds me of the roots of my eucalyptus