The importance of preparing the soil for a new lawn cannot be stressed strongly enough. This process creates the foundation for your new lawn and directly affects its ability to take up nutrients and water. If you put the hard work in now then you shouldn’t have to spend the time and effort later trying to correct the flaws that will be later be visible in the lawn if the soil is not prepared correctly. This soil preparation guide is applicable when sowing a lawn from seed and and when laying a lawn from turf.
The time taken to prepare the soil can vary greatly depending on the size of the new lawn, the previous use of the lawn site and the soil type.
The first step in preparing the soil is to remove any large objects that are on the soil surface, this includes old paving stones, bricks, stones, tin cans etc. If there is a layer of concrete or heavy paving stones that need removing you may consider hiring some stone breaking machinery (either machines or hand operated).
After this is complete you should inspect the lawn area for perennial weeds such as the ever common nettles, thistles and dock leaves and other nuisances such a brambles. Depending on your findings you can either dig our the weeds by their tap root or if the ground is covered in them you may want to use a chemical weed killer such as 2-4-D. For more information see lawn weeds and lawn weedkiller. If you do use a weedkiller then make sure to double check the manufacturers instructions regarding amounts to use per x ft square before application.
If not using weedkiller then do not just cut the weeds, dig them out by getting the tap root so they are permanently removed and don’t re-appear after a few months. Once you have removed the weeds add them to a pile and then burn them once all have been dug up.
If your lawn site already contains an old lawn or other vegetation trim the vegetation down so that it is near ground level. Machines can be hired / bought that will remove a thin layer of turf from existing old lawns. Alternatively old grass can be removed by removing turves with a spade. You can then stack these old turfs upside down and the old grass will decompose and form compost.
Now that the lawn site is clear of debris and vegetation is is necessary to get rid of any tree and shrub stumps / major roots that remain in the ground. If there is a shrub or young tree you wish to keep then dig it up and relocate it to a non-lawn area. Roots of trees and large shrubs can seriously damage the quality of a lawn as they will often compete, and win in the battle for sunlight, water and soil nutrients. The grass will become weakened, yellowed and patchy as a result.
You are now ready to dig the soil over and add any necessary soil conditioning materials (such as coarse sand, organic matter such as well rotted compost, bonemeal etc). These soil conditioning materials will help improve the texture of the soil, soil drainage, soil moisture retention properties as well as obtain a more preferable nutrient content and pH (acidity / alkaline balance).
Digging the soil should take place about 2 or 3 months before you want to sow or turf the lawn so that the soil has time to settle after being loosened. If you do not let the soil firm and settle after digging then you will find that the soil will settle after the lawn developed and dips and bumps will appear in the lawn.
Rake the soil level with a soil rake. If you are going to manually firm the soil (you can do this by treading the soil for small lawns or using a garden roller for larger lawn sites) then make sure that you only do this when the soil surface is dry. If you firm the soil when the soil surface is not dry then you will degrade the soil structure which will result in a weaker lawn.