SUSTAINABILITY  |  Read Our Commitment

Lawn Care - how to use biochar super compost and biochar

Tony Callaghan 07/10/2022

Lawn Care - how to use biochar super compost and biochar

Lawn Care using Biochar Super Compost 

Whether you have an existing lawn, plan on laying new turf, repairing patches or are re-seeding an area of the garden to create a new lawn our versatile biochar granules can help create ideal growing conditions without too much hard work.

Biochar and SF40 Biochar Super Compost:

  • Aids water retention
  • Increased nutrient supply to the roots
  • Decrease nutrient run off
  • Supports soil microbes and mycorrhizal fungi
  • Supports the formation and stability of colloidal humus
  • Improves soil tilth

You can find our high-quality biochar for sale along with other garden products from our store!

Which SoilFixer product should I use on my lawn/grass?




Top dressing (Autumn)yesyes
Liquid feed (Spring)

yes  (see liquid slurry)
Brown patches (Summer)yes
Seeding new lawnyes

Laying turfyes

* biochar requires inoculating/charging

Autumn lawn care

By October grass growth begins to slow down and the grass can begin to look a little worse for wear.


Over the spring and summer the lawn will have built up an area of thatch, which is a mixture of dead grass, moss and other small garden debris, this combination of materials prevents airflow through to roots, it can be removed by raking the entire lawn. This is hard work and your lawn may look a little bit bare once it is done but that is all part of the process! There are electric and petrol scarifiers available to buy, these are ideal for larger lawns and will certainly make lighter work of raking.

If it is the first time you have raked or scarified the lawn you may be a little bit alarmed by its appearance once it is completed, not only will you have a huge amount of thatch to either put on the compost heap or in the green waste bin but the lawn may look a little thin and patchy in places, this is completely normal.

Once scarifying is completed, a top dressing of 1-3 cm of SF40 Biochar Super Compost (a mix of activated biochar, humus and fine compost) can be added. This will help create a deep green colour and help prevent moss on lawns on heavy clay soil.  


The RHS recommends aerating the lawn every two or three years and concentrating on the areas that get heavy use and become compacted.  Spike the areas with a garden fork or an aerator tool, this increases airflow to the roots and creates perfect conditions for backfilling the holes with SF40 or biochar granules.

Top dressing

We recommend SF40 for top-dressing lawns as it is sieved below 13mm so it has fewer twigs and small bits of organic matter than traditional compost so it is easier to 'work in' to the surface. Over time, the biochar in the SF40 will work down into the root zone and form interactions with soil microbes resulting in improved grass growth. Simply sprinkle across the lawn. 

Shady lawns and grass

Grass lawns are an important fixture in most gardens; however, trees and buildings often decrease light levels affecting the quality of the lawn/turf. Trees and shrubs will compete with grass lawns for resources, such as water, sunlight, and nutrients.

Biochar and SF40 will improve the health of the soil and root/grass growth, but to improve an existing grass area you also need to consider:

  • Has the lawn area been seeded with a shade-tolerant grass variety? 
  • Does the soil in the shade also get water-logged?
  • Is the soil fertile?

If the spot is out of sunlight all day due to year-round, full-leaf cover from trees, then grass might not be the best option. Consider replanting with shade-tolerant plants. (See RHS list)

The Mississippi State Education section has a good list of shade-tolerant grass varieties.

If the soil is also heavy clay and prone to waterlogging, you may need to add a top dressing of sand/biochar to help with drainage. 

Laying a new turf or sowing lawn seeds

Autumn is the best time of the year to lay brand new turf. To prepare, dig out the space you plan to create the lawn and remove any weeds. Pay careful attention to the finer roots;  although they appear to be very small they could work their way back up as dandelions, thistle, plantain and more lawn loving weeds!

Here are the main soil mixes for lawns:

  • Just well-raked topsoil (note: topsoil varies hugely!)
  • 50% topsoil and 50% compost (favourite for turf growers)
  • 50% topsoil and 50% SF40 (the future for turf growers!)
  • 100% SF40 (i.e., a 5cm layer of SF40 on your topsoil) 

To buy our SF40 .... Biochar Super Compost click here.

Spring Lawn Care

You may have already made the first lawn cut of the year, but if you haven't, start with a high blade and gradually reduce over the weeks to your preferred height. If your lawn is prone to moss and weeds, here we will explain how our biochar granules and SF40 Biochar Super Compost can help.

Tackling weeds and moss really depends on your individual approach, there is a wide variety of weed and moss killers on the market, both chemical based and a number of effective treatments that use natural ingredients. You can also remove them manually but this can take some time and unless you remove the entire root, which is difficult with weeds such as dandelions, they are sure to return within no time at all.

Once you have weeds and moss under control, there are a few additional things you need to check for including:

  • Poor drainage leading to water logging – if you have to add drainage pipes, while dug out, add biochar
  • Compact soil leading to poor aeration and drainage – if you spike or cut out aeration plugs, backfill with 0-2mm biochar (Professional golf greens are using biochar for this)
  • Too acidic – a thin light coating of lime is the norm. But Biochar has a pH of 9.5 and it will also help reduce acidity. The increased microbial activity will also improve the root health as biofilms provide a protected neutral zone
  • Lack of feed – SF40 will provide short and long-term nutrients
  • Too close cutting – leave an extra 2cm height on the grass


Golf Greens 

An increasing number of golf courses are now using biochar to help improve their greens.

Greenkeeping is expensive and a highly-skilled task supported by professional courses and qualifications. Many golf greens are built from scratch to rigorous standards. The goal is to achieve the right combination of surface hardness/softness, speed of play, surface smoothness, resistance to wear and the desire to keep a perfect green open as long as possible – not quite “all-weather” but as close as.  

The high percentage of sand used in the soil mix tends to lead to rapid fertiliser leaching and runoff. Biochar offers the opportunity to improve greens; it holds nutrients, is porous and does not compact.

Although biochar can be applied as a top dressing, ideally you need to get the biochar down into the root zone. Here the microbes will inhabit the biochar and form symbiotic relationships with the roots – i.e. the microbes transfer nutrients to the roots and the roots in exchange transfer sugars (food energy) to the microbes.  After core-holing, biochar 0-8mm granules can to brushed into the 13mm core holes.

How to fix Brown Patches in your lawn

The usual suspects creating brown patches are:

  • Pet wee and pet poo
  • Drought caused by small differences in soil water holding capacity
  • Using a 'weed killer' rather than 'lawn weed killer'

Brown patches can be repaired by top dressing with SF40 and then reseeding. Remember to keep the seed well watered.

Below are two images of repairing weed killer damage:

What's going on?

The grass is starting to grow back into the brown area. It is likely the soil microbes are slowly biodegrading the weed killer; this is as expected.

There is a taller, dark green grass ring around the brown patch and distinct from the rest of the green lawn. The grass is growing much stronger in the ring near the SF60.


The SF60/SF40 is having a fertiliser effect. Applied as a top dressing, nutrients in SF60 get flushed into the brown patch increasing its concentration. The grass nearest benefits and becomes darker green.

Increased water retention is a known benefit of SF60. The brown patch with SF60 applied is holding more water. The grass nearest (in the dark ring) has access to more water than the rest of the lawn so it grows taller and faster.

The results are consistent with the greening and moss reduction achieved in previous years when adding super compost from our HOTBIN composter to specific areas of the lawn.  SF60/SF40 has a beneficial effect on lawn grass. Stronger, faster-growing grass will invade the brown bare patches.