Growing grass from seed is far more affordable than laying turf, but it also requires more care and attention since there’s much more that can go wrong.
However, it isn’t too difficult to do, as long as you know the right way to do it – and to help, here are 11 reasons why grass seed isn’t growing – and 10 tips that will help you fix it.
One reason could just be because you need to be more patient, so check out this video for info on how long it should take – and then read on to learn about other reasons grass doesn’t germinate and grow if this doesn’t solve it.
What does grass seed need to grow?
The first thing you need to understand when planting seed is that it requires four elements to germinate – warmth, water, oxygen and light. Without any of these four elements, grass seed will struggle to grow, and this is the first place to look.
Beyond this, there are also some other reasons why grass seed won’t grow, so let’s look at them now.
Reasons why your seed isn’t growing
1. Not enough water
The most obvious reason why grass seed isn’t germinating and growing into grass is that it doesn’t have enough water.
For grass seed to germinate, the ground needs to be kept moist – but not wet – for at least the first 10 days to two weeks.
If you let it dry out, the grass seed won’t germinate, so this may mean you need to water it every day – or even as often as twice a day during hot spells.
When watering, you need to ensure that the moisture soaks into the ground – otherwise, it will evaporate off before reaching the seed. On the other hand, you shouldn’t flood it – the key is finding the right balance.
To test, push a screwdriver into the soil to about 15cm – if it’s hard to do, you need to water more.
2. Compaction – not enough air
Grass seed also needs air to germinate since this is what helps activate the seed’s energy store, allowing the grass to feed on it.
This means if you spread grass seed over compacted soil, it won’t receive the necessary oxygen it needs and it won’t germinate.
Even if some seeds do manage to germinate, they will also have trouble sending down roots into the hard, compacted soil – so for this reason, you should ensure the soil is properly aerated before sowing.
3. Buried too deep – not enough light
Grass seed needs a certain amount of light to be able to germinate, so if you bury it too deep, you won’t achieve the desired results.
On the other hand, if the seed just sits on the surface, it will dry out too quickly in between waterings and also won’t germinate.
For best results, after sowing your grass seed, rake it into the soil to a depth of around 1cm. This will allow just the right amount of light to penetrate the soil while also helping it remain moist in the ground.
As a bonus, this will also help protect it from any hungry birds that might enjoy coming down and pecking at your seed before it grows.
4. Timing – planted at the wrong time
Timing is also key when it comes to planting grass seed, and in the UK, the best times to plant seed are in early autumn or mid-spring, with the former being slightly preferable.
In early autumn, the ground will still be warm, making it conducive to germination. After the grass sprouts, it will then spend the winter working on developing a strong root structure.
In spring, the ground may not have warmed up enough, so germination will be slower – and when the grass starts growing, it will want to flower straight away. However, mid- to late spring coincides with one of the main growing periods, making this a suitable time for sowing.
On the other hand, if you go to early or leave it too late, the ground will be too cold for germination, and you are likely to see poor results.
Similarly, if you try to plant in the middle of summer, conditions will be too hot – and there may also not be enough rainfall – making this a difficult period to successfully grow grass from seed.
5. Using the wrong kind of seed
Since the weather from one end of the UK to the other is broadly similar, this might not be such a problem as in some other countries, but choosing grass species that are adapted to the climate is important.
If you choose a grass that isn’t suited to UK weather, you might have a harder time of getting it to sprout and flourish.
6. Using poor quality seed
More of a problem is trying to grow grass from inferior seed. You might imagine that one bag of grass seed is much like another, but you’d be wrong – like with anything else, you get what you pay for.
A cheap bag of seed might seem like a bargain, but it could be old and out of date, full of fillers or inferior grass species, full of weed seeds or simply have a lower germination rate.
For these reasons, buying cheap seed can often be a false economy – and you’re much more likely to be successful by purchasing quality seed from a reputable supplier.
7. Poor soil preparation
Preparing the soil before sowing is an important aspect of sowing seed. Begin by rotovating the soil or turning it. Then tread it down, rake it over and tread it down again – check out this video to see how.
You may also decide to fertilise the soil if necessary before sowing.
If you simply sow the seed on compacted, infertile soil and hope for the best, you are much more likely to achieve unsatisfactory results.
8. Problems with the soil
Most grasses prefer soils that are slightly acidic, in the region of 5.5 to 7, so if the soil is below pH5.5 or above 7, grass may struggle to grow.
Grass seed also needs nitrogen in the soil to grow, and if the soil quality is poor, again, grass will not germinate and thrive there.
9. Incorrect application of lime
Related to #8, if you apply lime to the soil blindly, you may raise the pH to a level that grass won’t tolerate. Lime should be applied to soil that is too acidic – but if you overdo it, you will find that grass refuses to grow there.
10. Miscalculating how much seed
A common problem is miscalculating the amount of seed you sow since getting this just right is very important.
Remember that a lawn is made up of thousands of tiny plants, and if there are too many of them, competition for limited resources will be too high, and the plants will smother each other out.
On the other hand, thick, healthy grass smothers out weeds, but if you spread the seed too thinly, weeds will be able to gain a foothold, crowding out the grass you are trying to grow.
This means you need to measure the area to be seeded accurately – and then follow the grass seed supplier’s directions to ensure you use just the right amount.
11. Using weed treatments
One mistake that some people make when seeding lawns is applying pre-emergent weedkiller before sowing, the idea being that this will prevent weeds from growing, giving the grass the best chance of establishing itself.
This is a fatal error, however, since pre-emergent weedkillers work by preventing weeds from germinating and then preventing them from developing strong root systems.
The problem is, these weedkillers will have the same effect on your grass seed, so if you apply pre-emergent products prior to seeding, there is little chance that any of your seed will germinate at all.
As a rule, these products shouldn’t be applied to the area less than 10-12 weeks before seeding your lawn – otherwise, you are unlikely to achieve good results.
Why are you seeding at all?
When seeding your lawn, it’s also important to think about why you’re doing it. If you are reseeding to replace a lawn that keeps dying off, you might be better off looking at the cause because the chances are, your new lawn will keep dying too.
For example, is the ground compacted? Does it have the necessary nutrients? It is excessively shaded? Is the drainage adequate? Is it too dry? Are you following the best practices for mowing?
Thinking about issues such as these may help you nurture your existing lawn back to health much more effectively than simply throwing down new seed and hoping for different results next time.
Tips for success
As a summary, here are the top 10 tips that will help you succeed when reseeding or overseeding a lawn.
- Keep the soil moist but not wet during the germination period
- Allow enough air to reach the seed through proper aeration
- Don’t bury the seed too deep – rake it down to about 1cm
- Sow seed in mid-spring or early autumn for best results
- Prepare the soil properly through aeration, raking and fertilisation before sowing
- Choose good-quality seed for sowing
- Test the soil’s acidity and nutrient content and amend as necessary
- Calculate the area accurately and follow the seed supplier’s guidelines for quantity
- Avoid using pre-emergent weedkillers in the 12 weeks before sowing
- Consider why your grass needs reseeding in the first place and rectify any problems
Avoid simple mistakes and growing grass from seed can be easy
As you can see, many of the mistakes are easy to avoid once you know about them, and by understanding the requirements of grass seed and doing everything you can to provide the perfect conditions, growing a new lawn can be a fun and rewarding undertaking.