OVERSEEDING

Overseeding is a process of applying new seed across your lawn to thicken the grass. This process is very often carried out in the Spring and Autumn, as it is in the growing season but we also have adequate rainfall. 

This is commonly done when your lawn is looking a little sparse and is most commonly carried out after scarifying or raking your lawn. It is also advised to aerate the lawn beforehand. 

The key to getting overseeding to work is ‘soil contact’ - this is where the new seed makes contact with the soil. Seed is dropped on top of the lawn and you want it to reach the soil below this. If you don’t, it will not germinate. 

1. Preparation - Fertilise (3-4 days before)

When overseeding, you want to ensure that it is being applied to soil which is fertilised, to ensure that it has the necessary nutrients to germinate and thrive. So, make sure you distribute a lawn feed (not a weed & feed) about 3-4 days (or more) beforehand. Ideally you should opt for a pre-seed fertiliser as this shall help once the seed has germinated, but a seasonal lawn feed would be fine too.

Alternatively, a fertiliser can be applied after your seed has germinated, in which case you shall need this to be a pre-seed fertiliser, as the higher nitrogen levels of a seasonal fertiliser will affect the new grass. The benefit of applying the fertiliser afterwards is that it prevents the existing grass from growing too quickly, whilst waiting for the new seed to germinate.

If you are looking for a pre-seed fertiliser, the A1 Pre-Seed fertiliser is a good option and you can get it on Amazon.

2. Preparation - Watering

The seed should be applied to a soil that has plenty of moisture in it, as this is what activates the seed and allows it to germinate. You are looking for a lawn that is moist but not wet. You should be watering after you have fertilised anyway, so once you have applied your fertiliser, get watering too for 3-4 days beforehand. 

3. Preparation - Mow it Short

When overseeding, the seed is applied to the top of the lawn but it needs to make its way to the soil layer and the lawn can prevent it reaching the soil. So to maximise the soil contact, you will want to cut your lawn shorter than normal without scalping it. 

You should be aiming to cut it to around ¾ of an inch to 1 inch in height. 

4. Apply the Seed

Firstly, check how much seed needs to be applied. The packaging for the seed will normally provide this figure, so firstly refer to this. If this does not provide that information, aim for around 25 to 30g per square metre. 

When applying the seed, you will want to look at a spreader to do this, so check out the buying guide for the different types and their ratings.

You shall want to apply the seed in multiple passes over the lawn, as this ensures that it is evenly spread across the lawn. So before you start, make sure you divide the seed up for each pass. 

As a minimum, you will want to do 2 passes over the lawn. One should be up and down the lawn and then one side to side. You may instead want to opt for 4 passes - 2 up and down and 2 side to side. 

For a good quality seed, try out A1 Lawn general purpose seed on Amazon here

5. Roll the Lawn

So now, you will have plenty of seed in the lawn and some of it will have reached the soil but a lot of it will not have obtained soil contact yet. To make sure that you maximise the soil contact, rolling the lawn is a very helpful step. 

Ideally, you should use a lawn roller, but you could also use the roller on your mower, if yours has one fitted. If you don’t have a roller, then you still want to work the seed down to the soil level, which can be done by brushing the lawn or even walking up and down the lawn. 

6. Top Dressing

Many gardeners like to use a top dressing when overseeding, as this allows you to level your lawn whilst overseeding and maximises the soil contact for the new seed. If you do opt for a top dressing, this can be applied before the seed is sown and then mixed in with a rake/lute, or it can be applied after and cover the seed that has already been sown. 

If you are using this to maximise the soil contact, then you only need to apply a very light dusting of top dressing over the top of the lawn. You can opt to use a specific top dressing product, which is a mix of filtered topsoil and sand, or just a regular topsoil. 

This step is quite regularly missed when overseeding, but applying a top dressing will dramatically increase the germination rate of your seed, so make sure you do this. You may still be able to overseed without a top dressing, if you get lucky.

7. Water the Lawn Lightly

The new seed will need water to germinate and grow. So, you will want to lightly water the lawn to get water to this new seed. You will want to do this daily for 2-3 weeks, to maximise the germination. 

8. Mowing the Lawn

After overseeding, you will want to wait as long as possible before mowing your lawn, as to not disturb the new seed. Before you have overseeded, the lawn will have been cut reasonably short so you will be able to wait a little while before it needs another cut

Ideally, wait until your lawn is around 1.5 to 2 inches in length before doing the next cut. As always, stick to the golden rule of cutting height  and then work your way back down to the normal height for that time of year.