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How to prepare the soil for a new lawn in 4 steps

From weeding to the seedbed

Is your garden lawn patchy or damaged by disease? If it is beyond repair and needs to be re-laid from scratch, the best times of year to sow a lawn are spring and autumn.

In late winter and spring, between March and early May, the minimum soil temperature must be at least 10°C, even at night. Sowing cool-season grass species too early is risky: low temperatures can hinder seed germination, leaving you with a sparse lawn. On the other hand, if you wait until May or June, you run the risk of weeds, which are plentiful and highly competitive in the spring and summer. If, however, you decide to sow warm-season species, which thrive in the heat, it is best to do so between May and July.

Late summer and early autumn, from late August to October, are the best times to sow cool-season grasses, and are even preferable to spring: the soil is still warm and there is less pressure from weeds and fungal diseases. Be careful, however, not to delay too long: the lawn must be ready for its first mow before the cold sets in.

Today we’ll look at how to prepare the soil for your lawn and briefly review the main post-sowing care steps. Why is this so important? Because if the grass is patchy, weak, or overrun with weeds, this is often down to mistakes made during the preparatory work, the sowing process itself, and the first few weeks of the grass’s life.

1. Mowing and weeding

Prepare for sowing by thoroughly weeding the old lawn. If the grass is tall, cut it back to about 10 cm before weeding, then collect and dispose of the clippings: as usual, you can use a lawnmower, a garden tractor or a brush cutter.

To remove weeds, you can use, for example, a pelargonic acid-based product: this is available over the counter, is safe for both people and animals, kills grass and weeds within a few hours, and does not linger in the soil. Follow the recommended dosage, dilute it in water and apply it using a simple pressure pump.

2. Working and amending the soil

Once the old lawn has dried out, proceed with working the soil: the aim is to break up any compacted areas and clear the soil (see step 3). If you have a small lawn, you can use a spade; otherwise, we recommend working with a rotary tiller or rotary cultivator. The soil should be worked to a depth that is neither too deep nor too shallow—around 15-20 cm is fine—and the process should not be too aggressive, to the point of turning the soil into dust. Make several passes, changing direction as you go, until the clods of earth are broken down into small clumps.

During the final pass, work in whatever is needed to improve the soil’s properties. For example, sand—particularly if the soil is clayey and therefore tends to become compacted—and topsoil rich in organic matter if the soil is poor.

Before seeding the lawn, it’s a good idea to have the soil analyzed to understand its characteristics and determine how and to what extent to amend it. The ideal soil for a lawn should contain at least 70% sand, a maximum of 15-20% silt and clay (the finest soil particles) and 4% organic matter. Sand makes the soil porous, creating a favorable environment for the roots of the grass seedlings, which thus find space, water, and oxygen. Organic matter, on the other hand, is essential, amongst other things, as a source of nutrients.

3. Clearing and leveling the soil

Between each tilling session, rake to remove clippings of grass, weeds, their roots, stones, etc., gradually clearing the ground. Make several passes, crisscrossing the direction and removing material little by little, from the coarsest to the finest.

By raking, you not only clear the area but also level the ground for your future lawn. In addition to the standard rake, another tool for leveling is the leveling rake. You may need to move soil with a shovel from one part of the garden to another to smooth out bumps and fill in dips. Make sure you give the ground a gentle slope, so that it slopes down from the house towards the edges of the garden: this way, rainwater will run off and won’t pool on the lawn.

4. Preparing the lawn seedbed

Using a rake, spread a thin layer of lawn topsoil (about 5 mm) to create the seedbed and help the seeds to germinate. At this point, everything is ready for you to scatter the seeds of the grass mixture or the single grass species you have chosen.

Before spreading the topsoil, you might want to do a stubble cultivation: this helps eliminate as many weeds as possible that could potentially damage the lawn right from the start. Their seeds, in fact, remain dormant underground, waiting for the right conditions to germinate. To carry out stubble cultivation, water several times a day, as if you had actually sown the lawn (see the next paragraph). In about a week, the weeds will emerge: clear them away by pulling them up, for example with a rake, or by weeding again. Finally, work the soil again and level it.

Sowing the lawn and post-sowing care

How do you sow grass? To distribute the seeds in the right quantity and evenly, rather than scattering them by hand, we recommend using a manual wheeled seed spreader. The seeds must be fresh and suitable for the local climate, sun exposure, how you intend to use the lawn, etc. Follow the recommended amount per square meter to avoid a sparse lawn or, conversely, one where the seedlings compete with each other.

Follow up with a specially formulated fertilizer—such as a starter fertilizer, which is rich in phosphorus—to promote seed germination and root development. Lightly rake the area to mix the seeds and fertilizer, then roll over it with a lawn roller to press them slightly into the soil, so that the wind or heavy rain won’t displace the seeds.

Watering after sowing should be carried out several times a day, using small amounts of water: the aim is to keep the soil moist to encourage germination. Continue in this way until the lawn has fully germinated. From then until the first mowing, water once a day using a more generous amount. In the meantime, do not walk on the lawn.

Mow for the first time after sowing when the grass reaches about 10 cm. Mow only slightly (1-2 cm), when the lawn is dry, using sharp blades and making as few passes as possible. Follow the same guidelines for the next 2-3 mowings: the purpose of the first few mowings is not to regulate the height of the lawn but to encourage it to thicken. Ideally, the lawnmower should be lightweight so that it doesn’t flatten the grass under its own weight: in any case, you can straighten it up with a rake or a leaf blower.

Below are our tips from our lawn care blog: