Healthy plants require healthy soil, but what does that really mean? Let’s take a look at the importance of soil fungi and bacteria and how they help your lawn to thrive.

Healthy soil contains a complex mix of nutrients, moisture, insect life and also decaying plant-life and animals. Their balance is essential and their interdependent relationship makes soil healthy and productive. If their balance is upset soil productivity is at risk, as is the health of your lawn or other garden plants. There are many things we can do to promote soil health and if you give your soil the right support the benefits could be huge.


Soil health has previously focussed on physics and chemistry with less attention given to the biological elements. Physics are typically the digging, aerating and attention put into ‘working’ the soil to gain the correct consistency. This is often about introducing air spaces into the soil. Air is of course an essential element of life and should make up 25% of your soil composition. Water should make up a further 25% and the physical working of the soil relieves compaction and aids drainage. Waterlogging of your lawn will push air out of the soil causing biological death and seriously impacting your grass plants.


When lawns are affected by predatory pests, disease or weeds the addition of chemical treatments have often been the go-to approach to control these problems. As we begin to recognise the importance of reducing our chemical input we need to look towards other ways of managing these issues. A healthy lawn, on healthy soil, with a great biological balance, will require less chemical intervention.


Now this is where I get excited. What takes place within the soil is fascinating. Understanding the relationship between plants above the ground, their roots below, the bacteria and fungi living within the soil and the animal life that share this soil with them will help you understand why soil biology is so important.

Most of us will remember from school the basics of plant life. Green leaf plants use energy from the sun along with water and air to photosynthesise. This is how plants create the food they need in the form of carbohydrates – sugars. However, the plant only uses some of this food and the rest is excreted from roots into the soil. Soil bacteria are attracted to the simple carbohydrate released by the plants. They use this as a food source and as they break this down, they release nitrogen. Nitrogen makes up the major component of plant nutrition and is essential for the growth of green leaves. Making more natural nitrogen available to your lawn will greatly reduce the requirement to add it as a lawn feed fertiliser.

The Bacterial Barrier

Not only does bacterial action within the soil make food available to your lawn, it also helps to protect your grass plants from attack. There are many organisms living within the soil. Not all of them are good. The bacteria within the soil that is feeding from the excreted carbohydrate has a vested interest in ensuring the plant that’s feeding it stays alive. To this end it works hard to protect the plant from attack. Amongst these pests are nematodes which become trapped and then digested by the root bacteria. That’s nature for you, isn’t it wonderful!

Boosting levels of carbohydrate within the soil will encourage higher populations of beneficial bacteria. Our specialised summer nutrition contains many different beneficial elements, one of which is based on molasses, a sugary substance very high in carbohydrate. You can almost hear the bacteria eating it (I’m joking!)

Bacteria and salt

Nitrogen for lawn feed comes in many forms. Different forms of nitrogen contain different levels of salt – lawn care professionals call this the salt index. Cheaper forms of nitrogen have a higher salt index. Many of the lawn fertilisers available off-the-shelf have cheaper ingredients and higher salt index. Professional lawn care providers would typically look to use lawn fertilisers that have a low salt index. There’s a really important reason for this. Salt kills bacteria. Think about why we use salt to cure meat, that’s to stop it from rotting – being broken down by bacteria. If we add high levels of salt to our lawn soil it will damage the essential bacteria within it. Promoting good bacterial growth within your soil reduces the need to add soil nutrition.

Fungi – he’s a fun guy

Fungi are amazing things, they feed on carbon and are brilliant at breaking down woody substances and plant matter. That’s why you find loads of them in woodlands. The fleshy toadstools that you find above ground are actually the fruiting heads that carry the fungal spores – basically the seeds that create new fungi. What you see above ground is connected to a massive network of the fungi within the soil. If you have toadstools on the surface of your lawn it’s often a sign that you have good, healthy, functional soil. When you find mould growing on your food that’s basically fungi breaking down the carbon in the food – remembering that salt would stop this process and preserve the food. Fungi doesn’t like salt. I’m unsure how salt feels about fungi!

Now let’s imagine a grazing animal is looking for food. If it’s in an area where there is poor food it could wander off and find something better. Plants don’t have that ability and their chance of finding food is limited to how far their roots reach. Well, it would be if it didn’t have a relationship with fungi. A little like their relationship with bacteria, plants create a mutually beneficial relationship with the fungi in the soil and because of the fungal network plants can then benefit from far greater access to nutrients and moisture within the soil. This can create an area up to 1,000 times greater than that of the plant roots themselves. So, by increasing the population of beneficial fungi within your lawn soil, we can reduce the need to add water and food. But fungi defend the lawn too.

The fungal barrier

Not all fungi are beneficial. In-fact there is a plethora of fungi that can cause major lawn issues. These attack the grass plants when conditions are right and by the time you notice their impact it’s often too late to take action. Prevention is better than cure. Previously regular applications of fungicide were used to defend grass against attack. However, these may also have an impact on beneficial fungi and their use should be minimal and avoided if possible. Defending against attack is by far the best strategy and this is where beneficial fungi are important. When you watch the growth of fungi under a microscope you can observe something spectacular. As two fungi sense each other their growth stops. Beneficial fungi around the roots of a plant create a virtual ‘force-field’ which protects them from attack.

Support your Soil

Our recommendations are simple. Mulch mow if possible. Mulch mowing leaves the clippings behind and this then returns decaying plant life back to the soil and feeds fungi. Minimise the use of chemicals and fungicides. Use low salt index fertilisers so as not to damage microbial life. Aerate the lawn at least once a year to ensure there is plenty of air spaces in the soil. The life within your soil needs air to survive – we all do.

Our professional approach to lawn nutrition ensures we add what’s necessary to support this complex network of relationships. We take an ‘organic where possible’ approach. We recommend the addition of carbon through lawn dressing as it feeds fungi and the compost element of the dressing contains plenty of soil bacteria which can then multiply within the soil. We also add carbohydrate in our summer liquid feed. This feeds the bacteria and the bacteria helps feed and protect the grass. Many of these things you can do yourself, but it’s often cheaper and easier to ask for the help of a professional.