How long do grass seeds take to grow? Germination Explained

So you’re thinking of sowing a new lawn? We can help you to develop a lawn which will be the envy of your neighbours, for a fraction of the cost of buying turf. Use our certified seed and follow our step-by-step guidelines and within a few months you can be using your new lawn. Tips include how to prepare the seedbed, sowing techniques and advice on how and when to water your newly sown seed.

You will also learn about the length of time it takes for grass seed to germinate, how to get your seeds off to a good start and how long to wait until you can start using your lawn, as well as the timing for that all important first mowing session.

Our handy troubleshooting section sets out the answers to many common questions, such as the reasons why the seed has not sprouted and how to protect the lawn seed from bird damage.

How long does grass seed take to germinate?

In the springtime, it will usually take 5-15 days before your grass seed germinates. The growth rate will depend on soil temperature, water and sunlight availability, seed-to-soil contact and the type of grass you are trying to grow.

Of course, you will need to have made the right preparations, by picking out any debris or large stones. The soil must be well raked, to create a fine seedbed. It should also be lightly compressed, to remove air pockets and encourage seed-to-soil contact. You can do this by gently treading the ground with your gardening shoes or wellies.

What temperature does grass seed need to germinate successfully?

Like many of us, grass seed prefers warm conditions. A general rule for the UK is for the soil temperature to have reached at least 10 degrees C and below 30 degrees C for at least a couple of consecutive days. For most parts of the country, that means mid-to-late spring. Although the air temperature may feel warm and you are ready to put your winter woollies into storage, it will take longer for the soil to catch up.

Can the germination process be sped up?  

It’s natural to be in a hurry to see your new lawn start to sprout, and you should lightly water the area to moisten the top layer of soil. Be careful, though, because overwatering can lead to seed rotting and increase the risk of fungal disease infection. Aim to moisten the top one inch (2.5cms) of soil.

Always consider the amount of rainfall over the previous 24 hours’ rainfall before watering. There’s no point in getting the hose out if the soil surface is already damp.  It’s good to be enthusiastic, but don’t overdo it! As the lawn starts to appear, reduce the watering frequency, but slightly increase the volume of water applied if the soil surface is dry. Be guided by the weather.

Your seeds will germinate and grow faster if the soil contains plenty of nutrients. Our Pre-seed Fertiliser 6-9-6 has been specially designed to get your seeds off to the best start. Ideally, spread the fertiliser on the soil about 3-5 days before sowing.

How do you know if grass seed has germinated?

You will know that your grass seed has germinated successfully when you see the seed sprouts pushing up through the soil. They are usually bright green and will be a very welcome sight. Exercise patience, because germination depends on several factors. If you haven’t seen any signs of your new lawn a fortnight after sowing, make a slit in the soil with a spade and take a close look at the seeds. If they haven’t changed from their original colour, or they show signs of mould or rot, something may have gone wrong.

How long does it take to make a usable lawn?

That’s a tricky question to answer, but you should wait for at least three weeks before even setting foot on your newly sown lawn. If you have pets, try to avoid letting them walk on the area for a couple of months, if possible. You can fence it off with whatever you have to hand – it only needs to be a temporary measure.

As long as you have followed the correct advice, you can start to use it lightly after the first two to three months or so. That means postponing garden rugby or football matches until later in the summer. If you damage the vulnerable young grass plants, it will take longer for the lawn to become fully established and you may have to do some reseeding in the autumn.

When should I make the first cut and how?

It’s best to leave the lawn mower in the shed until the grass has grown to about three inches (7-8cms) tall. This will encourage it to put out more shoots from the base and it will thicken up your lawn and make it more resilient. Most grass seed mixes will reach that height at about 6-8 weeks after sowing. 

Don’t forget to check for any stones or other hazards before mowing and set the blade to its highest setting. The mower blades should be clean and sharp. Cutting wet grass is asking for trouble, so wait for a dry spell.

Troubleshooting

Why is my grass seed not growing?  

Has the seed been sown when the soil temperature was too low? Your new lawn may eventually appear once the soil temperature has caught up with the air temperature. Nevertheless, there is a risk that the seed will be spoiled, especially in a wet weather spell.

Has the seed been sown when the temperature was too high? Hot and dry is not a good combination for successful grass seed germination. That is why spring and autumn are the best times for sowing. Don’t wait until mid-summer to decide you want to buy seed for a new lawn.

Does the seedbed allow for good seed-to-soil contact? Cloddy lumps and air pockets will stop the seed from sticking to the soil and result in poor germination. Use a rake lightly on the surface to mix the seed and soil together. This will also help to stop the seed from blowing away.

Is the area getting enough sunlight? Grass really needs about 4 hours of sunlight a day for strong growth. If your proposed lawn area is shady, consider using one of our specialist grass lawn mixes for shady areas. Yes, you’ve guessed it! It’s called Shady Lawn Grass Seed.

Have you given the seedbed a good feed? A starter fertiliser should have been added to the seedbed, and the lawn will also benefit from fertiliser in late summer, and again in the autumn. Our Pre-Seed Fertiliser 6-9-6 is ideal for new lawn seedbeds. It can also be used as a tonic any time between April-October.

Have you covered the seed with a layer of topsoil? The seed needs access to sunlight, so it’s not a good idea to cover the mix after sowing.

Have the birds eaten all your precious grass seed? This is a common problem and difficult to overcome. If you feel it is a risk, you could cover the new lawn area with a layer of fine mesh – you could use tent pegs to stop the cover from blowing away. If you already put out food for the birds, make sure the feeders are kept topped up, to keep them from snacking on your new lawn.

Have  you sown the right volume of seed? If you are starting from scratch, you will probably need about 30 grammes of seed for every square metre, depending on the selected grass mix.

Is the soil compacted? Just like us, grass plant roots need oxygen to survive. This problem is usually related to poor seedbed preparation. The top few inches of soil need to be well broken up before the seed is sown.

Is there too much competition from trees or shrubs? Large trees and shrubs close to the lawn can put out hungry roots which can rob your young grass plants of water, nutrients, and sunlight.

Is your soil too dry or too wet? The grass seed will need water little and often for optimum germination. Use a fine sprinkle setting on the hose to avoid disturbing the soil too much. Be careful not to overwater, as it will wash away the seed. Overwatering will also make the roots ‘lazy.’ They will stay close to the surface if they have a constant water supply. If they don’t reach deep into the ground, they will struggle to find moisture later in the season, when the weather has warmed up and your attention is focused on enjoying your lovely new lawn.

Is your young grass suffering from pests/diseases/contamination? Tiny fungi growing among the grass blades could indicate a lawn disease, while leatherjackets and chafer grubs can lead to patchy emergence. Allowing your dog to pee on the grass can cause scorching, due to its high nitrogen content. It can also show up as dark patches. Water well in the appropriate area, if you have a dog that tends to pee on the same spot.

Seed from Rural Supplies is DEFRA approved, meaning that the seed has passed quality testing. All our seed is certified and has a minimum germination rate of 80%. This means we can confidently say that our seeds will germinate, if sown under the correct conditions and cared for properly post-sowing.

Is your soil pH suitable for grass germination?

If your grass has failed to germinate, it’s also worth testing the pH of your soil. Different grass species need different pH ranges to grow and thrive.

If your seed has failed to sprout, consider testing the pH to check it matches the range needed for that specific seed to grow.

Soil that is too acidic or too alkaline can also impact nutrient availability, with the elements grass needs to grow becoming less available even if they are present in the soil. For example, acidic soils can lead to aluminium toxicity which affects root growth, while alkaline soil can cause deficiencies in key nutrients like iron and magnesium.

Similarly, if the pH balance in the soil is poor, it will also affect microbial activity and this is integral in breaking down organic matter and delivering nutrients to the grass.

An added advantage of testing soil pH is that it will also help to identify any other underlying soil issues, such as compaction or nutrient deficiencies.

The good news is that correcting the pH of your soil is relatively simple. By using targeted soil amendments you can adjust the pH to the optimal range for grass growth. For example, if the soil is too acidic, you can add lime to raise the pH, or if it's too alkaline, you can add sulphur or other acidifying agents to lower the pH.