How to Overseed Your Lawn

Is your lawn looking a little sparse? Are there bare patches caused by the damp weather/dry weather/pet urine?

No amount of fertilisation will help. But don’t worry, you don’t need to go ahead and replace the grass - overseeding your lawn can help.

Overseeding is the process of sprinkling lawn seed onto your existing lawn. This can keep it looking healthy, full, and luscious.

But you need the correct conditions for it to be worthwhile, and the right technique. There is also a lot of emphasis on the preparation of your grass. You will need to use a lawnmower and possibly even aerate your lawn to give your seeds the best chance of getting down into the soil and germinating.


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All your questions have been answered below. Follow our Speedy guide on overseeding your lawn.


A step-by-step guide to overseeding your lawn

Unlike sprinkling wildflower seeds and hoping for the best, there is a knack to the best lawn overseeding practices.

Before overseeding, fertilise your soil around 5-7 days beforehand. This will give your soil good nourishment and optimum growing condition while leaving enough time to ensure the fertiliser doesn’t react with the seeds.


You will need:


  1. Buy the right lawn seed

Higher-quality seeds will likely have a better germination rate. So, if your grass is in urgent need of attention, invest in some quality seed.

If you are just doing an annual overseed of the full lawn, cheaper alternatives can often give you more seed for your money.

Most seeds will germinate within 7-14 days. Higher quality seeds could germinate faster in the right conditions, so again invest if you want to get the lawn ready ASAP.

Measure your lawn before you buy, to check you have enough seed before you start.


  1. Mow the lawn first

Mow your lawn to around 3cm before overseeding. This will remove old grass and give your seeds a better chance of actually reaching the soil.

We have some lawnmowing tips available to read here. Ensure your grass is dry before mowing, and never cut more than 1/3 of the grass's full length. If it needs to be much shorter, try to mow on two separate occasions instead.

SPEEDY TOP TIP: A mulching lawnmower can help put nutrients back into the soil, so use one of these for an extra boost.

Always wear eye protection, work boots, ear protection, and gloves when working with gardening tools such as lawnmowers, scarifiers, and aerators. You can purchase all the PPE you need from Speedy online or in our service centres.


  1. Aerate & scarify your lawn

Your grass seeds need contact with the soil to germinate. Ideally, the grass will actually germinate just below the soil's surface. But it won’t if your soil is heavily compacted.

Grass needs well-drained soil for healthy growth. Air also needs to be able to get to the roots. So, you will likely benefit from aerating your lawn before sowing the grass seed.

Any soil which is hard and compacted will be broken up, providing air, light, and water to the grass’s roots. The grass seed will also fall into these small holes, giving them a better chance of rooting deep into the soil and not just sitting on the top of the lawn.

Before you aerate the soil, check the lawn for any signs of dead grass and moss after mowing. If there is, use a lawn scarifier to remove it. The grass can’t grow, otherwise, and you don’t want to push the moss down into the ground with the aerator.


  1. Overseed

Only now is it time to overseed! The preparation will be worth it.

Remember to check your lawn temperature is over 10°C first. Then, water your lawn using a watering can or hose. Sprinkling onto the dry ground could mean your seed just blows away in the wind, and the seeds need to be slightly moist to germinate too.

Follow the instructions on your chosen grass seed. You’ll have to sprinkle a certain amount per square metre, so check you’ve got enough.

You can sprinkle by hand or use a seed spreader for more accurate results.


  1. Press the seed to the ground

The seed will only germinate if it has made contact with the soil surface. So, you may want to press it down to the ground.

A grass roller could help here, as could simply walking on the soil with the biggest, heaviest shoes you have. Check after every few steps that you’re not just picking the seed back up on your soles; wear shoes with flat soles ideally.

Alternatively, use two large planks of wood and stand on one for a few seconds, before stepping to the next, and repeating.

However you do it, just check the seed remains evenly spread and in place.


  1. Water

Water your lawn every day until the seeds have germinated. Water little and often, otherwise seeds could either wash away or become too damp.

Watering will activate the fertiliser again, too. You might want to fertilise the soil again around 5-7 days after overseeding.


  1. Be patient

Grass shoots can take around two weeks to properly appear, so don’t be disheartened if it looks like nothing is happening at first.

Avoid walking on the shoots when they start to appear, as it could damage them. Corden off the area if you need to stop pets and children going onto it.

After around a month, you can mow your lawn. This will give your new shoots a chance to get strong enough.




When should I overseed my lawn?

Don’t wait until your lawn is looking worse for wear before overseeding. It is better to overseed regularly than to wait until your grass is bare and patchy.

However, the conditions need to be right for grass seed germination. Soil temperature should be at least 10°C, so wait until the nicer spring weather.

The soil warms up slower than the air, so it could be April before overseeding is worthwhile. You can do it before then, but it could just result in wasted grass seed!

Use a thermometer to be sure if you have one. Grass will start naturally growing in spring when the weather warms up, so now is also a good time to see where really needs some attention.

Then overseed again in autumn, at the very least. You can do it again in summer, but you want minimal footfall on the grass, so ensure you do it when the kids aren’t playing football.

The temperature also can’t be too warm. Anything over 20°C could mean the seeds dry out before germination, so if you do overseed in summer, keep the lawn really moist using a hose or watering can every other day.


Can I add too much seed to my lawn?

Yes. Adding more than the recommended amount of seed to your lawn results in lower germination rates, and weaker grass shoots. If too many germinate in one area, they will fight for their share of nutrients and space.


How do I replace my lawn?

Overseeding can save a lawn, but if your grass is beyond the point of saving, you will need to replace the turf.

Use a turf cutter to divide the lawn into more manageable sections, before lifting the sod and disposing of it as per your local council's advice.

Add a layer of soil, then either lay new turf or create a lawn from seed. It is the same process as above, but you will have to use twice the amount of seed.

Read our guide on how to lay artificial grass if you want a no-maintenance approach.






Now all that is left is for you to follow our tips on overseeding your lawn. once your lawn is healthy, read our further guides on when to aerate your lawn, and how to mow a lawn.

You’ll find all the power tools and hire equipment you need right here. Why not start planning your next DIY project and open a Speedy account online or visit us in one of our service centres for all your tool hire needs?

Speedy has more than 200 local service centres across the nation, hire counters in selected B&Qs and nationwide 4-hour delivery. It has never been easier to hire the tools and equipment you need.


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