When Should You Plant Grass Seed?

Whether you're looking to breathe new life into an existing lawn or starting from scratch, we delve into when you should plant seeds and all the factors.
Written By: Archie Rich | Updated:
When To Plant Grass Seed
Archie Rich/DIY Works

Creating a vibrant and thriving lawn hinges on the careful timing of planting your grass seed. Knowing exactly when to sow is a crucial aspect that can significantly impact the success of your lawn. Regardless of your gardening experience, planting grass seeds is relatively straightforward, and as you’ll see in our case study (further down in this article), it can be very satisfying to watch the daily transformation of the seeds.

When To Plant Grass Seed?

Unlike other countries around the world that benefit from a hot climate all year round, the UK isn’t that lucky. Therefore, you’ll want to plant your grass seed in spring or the end of summer for the best possible results. This is primarily because the soil is warm and damp, which is perfect for the optimal germination of your grass seeds.

However, there are some exclusions, as certain grass seed manufacturers may state when to plant grass seed on their packaging. However, as a general rule, the best time to plant grass seed is between March and April or August and September.

Once you’ve chosen a grass seed, below we discuss why mid-spring or late summer is the best time to plant it.

Why Spring or Mid-Summer?

1. Ideal Temperature

As you can imagine, the cold and wet weather during winter isn’t the best time to plant seeds.

Therefore, choosing the right time to plant grass seed is essential for optimal growth because it ensures favourable environmental conditions for germination and establishment. This is because factors such as temperature, moisture and sunlight availability directly impact seed germination and its early growth stages.

The ideal temperature of 8 to 10 degrees is what’s recommended for the grass seed to grow quickly. At 8 to 10 degrees, the temperature is neither too cold nor too hot, which is perfect for optimum germination of the seeds.

However, that’s not to say that the grass seeds can’t survive during the winter because they certainly can. It’s actually a common practice, and planting grass seeds during the winter is known as dormant seeding. This means that the seed will simply lay dormant until the ideal temperature of the soil is met, which is usually mid-spring. However, it’s worth noting that if you plan to plant grass seed in the winter, you’ll want to use a dedicated winter grass seed.

2. Soil Conditions

Determining when to plant grass seed is mostly based on the condition of the soil. As mentioned above, the ideal air temperature needs to be around 10 degrees, which is enough to heat the soil to around 6 to 8 degrees for optimum germination.

As this temperature is often achieved during spring, you’ll often get the odd spells of rain, which also gives the soil plenty of moisture. However, if it doesn’t rain, you can always water the seedbed daily with a garden hose.

Competition With Weeds

Weeds in a seedbed can be an issue while sowing seeds because they compete for nutrients, sunlight and water. They also create shade over the seeds, which can affect the growth of the sowed seeds.

However, as you are trying to grow fresh grass, you can’t simply use a weed killer.

Therefore, you’ll need to carefully weed the area by hand before they flower. Eventually, the grass’s growth will defeat the growth of the weed, but that’s only going to happen if you keep on top of your weeding.


Aftercare plays a crucial role in ensuring the optimal growth of newly planted grass seeds, and it includes regular watering to keep the seedbed moist and promote germination.

As well as watering, it’s important that you avoid walking over the seeded area to prevent disturbance and potential damage to the fragile seedlings.

Also, diligently removing debris or weeds that may interfere with the grass seedlings’ growth is necessary. Patience is key, and it’s advised to refrain from mowing the grass until it reaches an appropriate height of around 5 cm.

Other Factors To Consider

  • Proper soil preparation: Ensure the soil is loose (breadcrumb-like temperature is recommended) and any debris has been removed
  • Correct seed blend: Depending on the sunlight availability, you’ll want to choose an appropriate grass seed (i.e. a shade-specific blend for shaded areas that receive little sun)
  • Birds and other forms of nature: If you notice that birds are eating some of your seeds, you may want to invest in a suitable deterrent
  • Two-week weather forecast: Knowing in advance the weather conditions that your sowed grass seeds are facing can be a great help (Lots of sun and some rain are ideal). As most grass seeds take up to 10 days to grow, checking the two-week forecast (BBC Weather offers this) is highly advised.

Mid-Spring Case Study

We love displaying our first-hand experience at DIY Works, and below is a recent grass seed case study that we carried out. The lawn in question was at a family member’s house where their grass decided it didn’t want to be grass anymore!

how long for grass seed to grow

Archie Rich/DIY Works
how long grass seed germinate

Archie Rich/DIY Works

After sowing the grass seeds in April, we began to see signs of germination in just 4 days (as shown in the second photo). After 10 days, we started to see the formation of grass (third photo), and then after 14 days, we had thick grass (4th photo). Depending on the grass seed you use, you should see similar germination as we did in the photos.

how long does it take for grass seed to grow

Archie Rich/DIY Works
how long does grass seed take to grow uk

Archie Rich/DIY Works

As shown in the images, we did have a few patches, but we overseeded these areas so that they matched the new grass.


Watching your seeds eventually spout into grass can be very satisfying and transform your garden. However, to give the seeds the best possible chance of growing, you’ll want to plant grass seeds in mid-spring or late summer.

If you require further information regarding when to plant grass seed for the fastest and best possible growth, feel free to contact us, and we will try to provide our assistance where possible.

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