How to overseed a lawn

When it comes to overseeding, preparation is the key to success. Before beginning the overseeding process, it's important to inspect your lawn for moss presence. If left untreated, moss can hinder seed contact with the soil and compete with new grass seedlings for water and nutrients.

If there is no moss present on your lawn or if it is under control, proceed to step 2.

Otherwise, treat the lawn with a moss killer. These are available in dry granules or liquid form, which can be spread or sprayed over the lawn and watered in.

In step 2, we will physically remove the moss through scarification.

After applying the moss killer, it's crucial to let it take effect before scarifying or raking out the dead moss. This duration may vary depending on the product used, but typically it takes around 1 to 2 weeks. Premature removal of dead moss can cause the spores to spread, which can lead to a reappearance of the moss.

Refer to the manufacturer's instructions for the moss killer to determine whether there is a waiting period before overseeding after treatment, as this can vary from a week to over a month.

Scarification is the process of removing the accumulated build-up of thatch from a lawn, which is a layer of dead and living plant matter that sits just above the soil, including the moss we treated in step 1.

For smaller lawns, scarification can be done manually using a spring-tine rake or a manual scarifier. However, for larger areas, a powered scarifier is almost certainly required, as scarifying is a labour-intensive job. It's important to make sure that the scarifier blades penetrate deep enough to remove the thatch effectively but not so deep that the healthy grass roots are damaged.

For more information on scarification check out our comprehensive guide How to Scarify a Lawn.

To help promote root and shoot development and improve disease resistance, it's a good idea to apply a pre-seeding fertiliser, also known as a starter fertiliser, to your soil.

This will enrich your soil with the necessary nutrients to assist your new grass to become well-established.

To evenly apply the fertiliser across your lawn, you can use a drop or broadcast spreader at the rate specified by the manufacturer. This will ensure that your lawn receives the appropriate amount of fertiliser for optimal growth.

It's time to sow the seeds for a lush green lawn!

While you can always spread the seed by hand, it's recommended to use a spreader for a more even distribution.

For smaller lawns, hand spreaders work well, but for larger areas, opt for a drop or broadcast spreader.

The recommended application rate is usually mentioned on the bag, but as a rule of thumb, apply 28-35g of grass seed per square meter when overseeding. For bare patches, increase the rate to around 40g per square meter.

Applying excessive seed can cause competition for resources among the seedlings, leading to stunted growth and failures after germination. Thus, it's important to apply the recommended amount of seed to promote healthy growth and prevent overcrowding.

Watering your seed is crucial for successful germination.

The goal is to keep both the soil and seed moist.

Water the area once a day for at least five minutes, adjusting as necessary during dry or damp spells. Ensure there are no dry patches, which may require you to reposition the sprinkler during the process.

Using a sprinkler is recommended to avoid displacing the seed with direct water pressure from a hose.

It's also a good idea to keep an eye on the weather forecast, as rainfall can save you time and water.

Once the grass has reached a height of around 3 inches, which typically occurs 2-3 weeks after seeding, it's time for the first mow.

When mowing, use the highest setting on your lawn mower and avoid cutting more than 1/3 of the total height of the grass blades.

Throughout the growing season, continue to mow your lawn at least once a week.

Regular mowing is crucial for maintaining a healthy lawn, as it encourages the grass to grow thicker and promotes overall lawn health.