Mycorrhizal Fungi for Lawns: Worth It in the UK?

By Joe, Founder of Dr Forest · Sep 2026 · Edited 4 Oct 2026 · 5 min read

Mycorrhizal fungi are soil fungi that team up with plant roots and help them take up water and nutrients. Plenty of lawn products now contain them. Here is what the research says about whether they do anything for a lawn.

Do lawns already have them?

Almost certainly. Researchers at the University of Rhode Island examined more than 200 golf green root zones and found that "virtually every one" contained these fungi. Greens that had never been inoculated were, in most cases, already "highly mycorrhizal" within one to four years.¹ An article by a University of Wisconsin turf professor notes that older greens hold more spores and more species than new ones, so the fungi build up on their own over time.⁴

New golf greens are built on sand, which starts out with few of these fungi. A lawn on ordinary garden soil is even more likely to have its own already. 4

What studies show on new lawns

The best result comes from the same Rhode Island work. Spores of one fungus, Glomus intraradices, were mixed into a new sand root zone before seeding bentgrass, and some treatments were about 10% faster, but grass given no fungi ended up with just as much fungus in its roots.¹ The same researchers added that while inoculating a new green at seeding "is likely to result in a more rapid establishment… in the longer term it may not be necessary".

Results on lawn grasses are weaker. A 2004 trial inoculated a lawn mix of Kentucky bluegrass, red fescue and perennial ryegrass at sowing, with no watering or feeding. Grass given G. intraradices at 40 to 60 mL per m² established faster than grass given a second fungus, but the published summary does not report a comparison with untreated grass.² The most recent field trial, in Minnesota in 2025, sowed Kentucky bluegrass, perennial ryegrass and hard fescue with and without a mycorrhizal inoculant applied during establishment. The inoculant "did not impact species cover and had little effect on reducing symptoms of drought stress".³

What studies show on established lawns

The evidence here is thin and mostly negative.

• Applied after aeration: a two-season University of Wisconsin trial added fungi to a mature bentgrass green at intervals after aeration, on sand low in phosphorus, where the fungi should have the best chance. The published summary does not say what form the product took. "Mycorrhizae did not result in increased turfgrass visual quality, clipping yield, or clipping P content."⁵
• Sprayed on: a 2025 greenhouse trial mixed a commercial powdered inoculant with water and sprayed it onto the leaves of mature creeping bentgrass four times over three weeks. The product had "relatively low effectiveness" compared with the other treatments tested.⁶
• The one positive result: a UK study added mycorrhizal inoculum to a golf green and saw more root colonisation and more bentgrass, with a suggestion of less annual meadow-grass.¹⁰ The summary does not say what form the inoculum took.

Do shop-bought products work?

This is the biggest problem. Three independent tests in recent years found most commercial products did not work:

• Of the 25 tested in sterilised soil, 84% "did not lead to mycorrhizal root colonization, demonstrating that these products did not contain viable propagules". In soil that already had its own fungi, adding a product did not increase colonisation.⁷
• A 2024 University of Kansas test found that most of the shop-bought products colonised roots in one pot out of five, or none, and some carried Olpidium, a fungus that attacks plant roots. The lead author also sells an inoculant, which the paper discloses.⁸
• A 2025 Swiss study tested 16 products. Only three colonised roots, and none of the seven sold for home gardening formed the partnership at all.⁹

The fungi are alive. If they die in storage or the product was never made properly, there is nothing to work. That is why we keep a conservative use-by on our own powder.

Are granules effective?

Most mycorrhizal products sold for lawns are granules, because granules go through a spreader and land evenly over a large area. A fine powder is much harder to spread across a whole lawn.

Being easy to spread is not the same as working, though. None of the lawn and turf trials above used granules, as far as their published methods show:

• Rhode Island (positive): spores mixed into the sand root zone before seeding.¹
• 2004 lawn mix: inoculum applied at seeding, at 40 to 60 mL per m².²
• 2025 bentgrass trial (little effect): powder mixed with water and sprayed on the leaves.⁶
• Minnesota, Wisconsin and UK trials: the published summaries do not say what form was used.^3,5,10

The only granules we found tested were in the 2025 Swiss study. Two of its seven home-garden products were granules, one of them labelled for spreading at 100 to 150 g per m². Like every home-garden product in that study, neither colonised roots.⁹ Those were pot tests, not lawns, and neither product was sold for lawns. On an established lawn, granules also land on top of the grass, far from most roots, and we found no trial showing that works.

So granules are the practical format for covering a lawn, but there is no good evidence that they make a difference.

If you still want to try it

The method behind the best result was spores mixed into the soil where the roots would grow, before seeding, not spread on top of an existing lawn.¹

• New lawn from seed: mix the product into the soil just before sowing, or mix it with the seed.
• New turf: dust it on the prepared soil just before each roll goes down.
• Plugs: put it on the roots of each plug as it goes in.
• Go easy on phosphorus: the best inoculated turf in the Rhode Island work had "frequent applications of a low-P fertilizer", and heavy phosphorus feeding suppresses the fungi.^1,11
• Check the date: buy a product with a clear use-by date, because the fungi die with age.

Our Mycorrhizal Fungi Powder is a fine powder made for coating roots when planting trees, shrubs, roses and veg. It is not made for spreading over a lawn, and we would not recommend buying it for an established one.

Related: How and when to use mycorrhizal fungi · What are mycorrhizal fungi?