If you’re looking for some advice about when to sow grass seed, you’ve come to the right place. Our comprehensive guide takes you through the seasons, to help you decide when to sow your grass seed. It covers spring, summer and autumn and there are also some tips on dormant seeding in the winter months.

By far the easiest and best time for sowing grass seed is from mid-March until late October, and your timing will affect how you manage your new seeds so they turn into a lawn that you can use as soon as possible. In spring, for example, you need to wait until the soil warms up before sowing, while in summer you will probably have to water the seedbed. The same applies if you are looking to sow grass seed to cover any bare patches in the lawn.

Getting the timing right for sowing your grass is just as important to success as preparation and aftercare!

What is the best time to sow grass seed?

Well, you can sow grass seed at almost any time of the year, but planting in the spring or the autumn gives you the best chance of creating a lawn that will make you proud. Mid-March until late October is usually considered the optimum period for creating a new lawn or filling in any bare patches in the UK. But the recommendation will depend on the weather conditions where you live. Grass seeds need to be sown into a warm seedbed and they will need plenty of moisture to germinate successfully.

Making a success out of sowing grass seed will require the soil temperature to have reached a minimum of 10 degrees C for at least a couple of consecutive days. It is worth checking your local weather forecast for the week ahead, before sowing. The forecast should be predicting that the temperature will not fall below the magic 10 degrees C figure. Avoid frosty periods, as they will prevent your grass seed from germinating, and you may have to resow.

In fact, the ideal soil temperature for planting grass seed is 15 degrees C, so don’t be in too much of a hurry to plant your lawn or fill in any bare patches of grass. It takes time for the soil to warm up in spring and to cool down in the autumn. Even if the weather feels warm outside, leave it for a few days, to allow the soil temperature to catch up. If the temperature drops suddenly, delay sowing your grass seed for a while and wait until it feels consistently warm outside.

Another consideration is soil moisture. We have had some very wet springs over the past few years but looking back on the weather records there have been some very low rainfall periods in early season. A dry spell is not the right time to sow grass seed, although there is an option for watering the newly planted area with a hosepipe, if the soil temperature is right. But it is advisable to check whether hosepipe bans are operating in your region, before going ahead.

Patience is key, and waiting for the right conditions will help to ensure that the result is a lawn that will be the envy of your neighbours.

What happens if you plant grass seed too early?

The main problem with planting grass seed too early is the risk that the soil temperature will be too low. Early frosts can also threaten the establishment of your new lawn, and flooding is another potential problem. Of course, we have seen high rainfall in every month of the year in recent times, but sowing your grass seed too early is likely to increase the danger of your seeds being ruined by too much rain water pooling on the soil surface, and/or the seeds being washed away.

Spring – March, April, May

March, April and May can be good months for sowing grass seed, although March is probably a little too early, as it can be a cold month. But as long as the soil is warm enough, you can sow your new seeds and sit back and wait for your new lawn to emerge. A lot will depend on seasonal conditions, as well as your location. In the South of England, spring soils tend to reach the optimum temperature more quickly, compared with Scotland, for example.

Summer – June, July, August

Grass seed that is sown in June, July and August will normally require watering, to help with germination. Plenty of soil moisture is needed in the summer months, to turn the young blades of grass into a lush lawn that you can enjoy. Little and often is the best policy for watering the seedbed for your new lawn. If it is very dry, we would advise watering early in the morning, and again at sunset. It will require watering every few days, if there has been no rainfall.

Avoid using high pressure sprinklers, because they will disturb the seeds and make the ground surface uneven. Don’t be too generous with the water, though, because over watering could ruin all your hard work. It could ‘drown’ the seeds, which also need access to oxygen and sunlight for healthy growth.

Very hot weather is another no-no, when it comes to sowing grass seed in the summer months. If the soil temperature is above 30 degrees C, the seeds can ‘cook’ in extreme heat. They may not germinate properly, even if you pay lots of attention to watering. In the UK, long periods of very hot weather are quite unusual, so wait until it cools down a little, before you start sowing.

Autumn – September, October, November

September, October and November are often considered the ideal months for sowing grass seed, because the soil will have warmed up over the summer and it will often be at the right temperature to start the seed germination process. Autumn is also a time when the amount of rainfall increases and that helps with maintaining soil moisture.

However, November may be a little too late for sowing in some parts of the country, particularly the North of England and Scotland. In the northern parts of the UK, November can be a cold month and there is a risk of frost, which can kill off the seeds. It really depends on the soil temperature, which must not drop below 10 degrees C. Your local weather forecast will tell you whether it is a good time to sow your grass seed.

Winter -  December, January, February

Winter is not really the right time for sowing grass seed, mainly because of cold soil temperatures, which will stop the seed from germinating. Even if there is a warm spell, the soil is likely to be wet for most of the time. A waterlogged seedbed in winter will take longer to dry out enough for sowing, compared with the spring and summer. There is also an increased risk of flooding.

Despite the general recommendations for sowing grass seed from mid-March to late October, there is a technique called dormant seeding that can be used, if you have no alternative but to sow your grass seed in winter. Don’t forget, though, frosted ground is probably going to be too hard to give you the opportunity to create a fine seedbed that will promote germination and encourage your grass seed to flourish.

The idea behind dormant seeding is to sow your grass seed when conditions are not right for germination, in the hope that it will survive beyond the winter and start to germinate when soil temperature rises to the magic 10 degrees C in the spring. Surprisingly, the success of dormant seeding depends on consistently cold temperatures. If the weather turns unseasonably warm, the seed could germinate and then be killed off when the temperature drops again.

The best grass seed mixes to use for dormant seeding will contain a high percentage of perennial ryegrass. If you are short of options and have to sow your grass seed in winter, you could try our Hard Wearing Lawn Seed. It does what it says on the tin and contains perennial ryegrass seeds, so it could be suitable for experimenting with dormant seeding. If you do plan to try it, wait until the autumn leaves have fallen from the trees before sowing your grass seed. They will have to be cleared away before the seeds are planted, to avoid smothering.

Nevertheless, it is generally best to follow the recommended advice and stick to mid-March until late October, for planting your grass seed.

In summary

Mid-March to late October is the best time to sow grass seed. This is generally when the soil temperature is warm enough to promote seed germination and strong growth.

For spring planting (March, April and May), wait until the soil temperature reaches 10 degrees C and monitor the grass seedbed, watering the top couple of inches in dry weather.

For mid-season planting (June, July and August), the soil temperature will be warm enough for germinating the grass seeds, but lack of moisture may be a problem, so lightly water the soil in dry weather.

For late-season planting (September, October and November), the soil should be warm enough, although November is leaving it a bit late. There should also be plenty of soil moisture available for germinating the grass seeds, but water lightly if necessary.

All of our Rural Supplies grass seed is registered with the Department for Environment, Food and Rural Affairs, so you can have confidence in our products.