UK: add mycorrhizal fungi to soil for new Forest Garden?

I'm novice, starting a forest garden in a suburban garden.

Is there any need innoculate the soil with mycorrhizal fungi spores?

I've heard of doing this on tree roots (at planting time - it goes direct onto the roots) but what about the rest of the soil where most of the food will come from? (we only have room for a few fruit-bearing shrubs, so most production will come from the ground layer). I'm planning on growing a lot of edible green plants, mainly taken from Patrick Whitefield's book "How to Make a Forest Garden".

Thus far the soil is...
- bottom: a bed of rotten wood (collected from an ancient mixed-broadleaf woodland)
- middle: the topsoil from the garden, with horse manure dug through it
- top: a mulch layer (not down yet)
- no plants in yet - they're awaiting germination in the propogator; all will be perennial greens and fruiting shrubs

I'm going for a no-dig regime so if anything needs to be dug into the soil then now is the time!
Any advice gratefully received...



(And OK, I know there is no *need* to innoculate the soil with mycorrhizal fungi spores because the fungi will come with time anyway - I suppose I'm asking whether it would be beneficial and if so, how to do it)

Your last comment indicates you have the right frame of mind -- you don't need to add mycorrhizal fungi, but when the opportunity arises, it's a welcome addition.

The way to do it is to always be on the lookout for a mushroom that you can grind up and sprinkle all over your forest garden. Puffballs and boletes are two groups of mushroom that are usually mycorrhizal. If you come across any of them on your travels, bring them back to your garden so their spores can take up residence. Whenever you bring in any biomass, be it manure or wood chips or some other type of mulch, try to bring some new spores along with it.

There should be plenty of mushrooms sprouting in the UK with all the rains you've had -- that is unless there has been too much rain and they got drowned along with a lot of other things. How is the mushroom collecting there now?

quote "bottom: a bed of rotten wood (collected from an ancient mixed-broadleaf woodland) "


John, wouldn't this layer already have been inoculated?

Miles Flansburg wrote:
John, wouldn't this layer already have been inoculated?

It should have plenty of white rot fungi, but they may be crowding out the mycorrhizal species. It's hard to know what kind of distribution of fungal species you have just by looking at hyphae -- they aren't that easy to tell apart. That's why whenever I come across a known mycorrhizal mushroom, I save it so I can put it in the blender and make a root drench with it. That's how you really get the roots inoculated.

Thanks !

Thanks guys.

The rotten wood I buried (mainly ash, hazel, hawthorn and oak) is likely to contain saprophytic mycelia ... but I'm not convinced it would contain a lot of mycorrhizal species as it was long-dead. And the mycorrhizal symbionts of trees are probably different fungal species to those of leafy plants (but now I'm speculating - I don't know this for sure).

The forest mushroom season in southern England is September-December, peaking in November. There is a lot of fungal diversity in my area (many thousands of recorded species www.fieldmycology.net).

I will collect some puffballs and boletes next autumn and hope for the best!

Thanks for the thoughtful replies.

I decided to buy a mycorrhizal fungi product to inoculate the roots of my new shrubs. It's called Root Grow, recommended by Martin Crawford (a well-known forest garden guru in UK).

Root Grow is something you put directly on the roots at planting time - I'm not sure if there is a way to do this once the shrubs/trees are in the ground.
It cost £8.72 (about 14 US dollars).

Root drenching on plants that are already in the ground works, but it's less effective than having the root bare where you can get some direct microbe to root contact.

In either case, you want to make sure that when you do a mycorrhizal application that the conditions are "just right": not dried out, not waterlogged, not frozen, and not bright and sunny. If you wait til sundown to apply it to plants in the ground and water it in good, the spores can get adjusted to their new home before the sun returns.