How much grass seed should I buy?

3 min read

sow grass seed

How much grass seed should I buy?

Turf Online offer a range of different grass seed mixes for gardeners who prefer to grow their lawn from seed rather than turf it.

But how do you work out how much seed to buy?

Here are some handy hints and tips.

Grass seed.  A little goes a long way so don’t sow too thickly

What is the sowing rate for grass seed?

To make a lawn from seed, you need to sow 25-30g of grass seed per square metre.  If you are over-seeding to renovate an existing lawn or sports field, 15-25g/m2 is plenty.

If you know the area of the lawn-to-be, you will be able to calculate your seed requirements.

How do I calculate the area of my lawn?

The easiest way to calculate the area of a lawn is to measure its length and width and type the results into our turf calculator on the home page of the Stewarts Turf website

Go to area calculator

This will do all the calculations for you, but it will then ask you to go ahead and choose a grade of turf.

It’s probably quicker to do the sums yourself though.

Calculating the seed requirement for a square or rectangular lawn

Measure the length and the width of the lawn in metres.  For accuracy, always use a measuring tape and measure at least twice – just to check that you did get it right first time.

Multiply the length by the width to find the area in square metres and then multiply that figure by 0.03 Kg to find out how much seed you’ll need.

For over-seeding, calculate the area then multiply by 0.025 Kg.

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As an example….

My lawn is roughly rectangular (it does have curved edges but that won’t make a lot of difference to the end figure).  It is 18.4 metres long by 12.6 metres wide.

The area is,

18.4 x 12.6 = 231.84 square metres – we’ll call it 232 m2 for the sake of simplicity

232 m2 x 0.03 Kg = 6.96 Kg of seed.

I’m going to order 7 Kg of the Landscaper Grass Seed with Rye

But wait!  That will cost me £77.72 including delivery


Maybe I’ll order a 20 Kg bag at just over £80 inc delivery – then I’ll have some left over for repairs AND I can share the bag with my next door neighbour and my daughter.

Calculating the seed requirement for a circular lawn

Same as for a rectangular lawn – measure the widest part of the lawn in metres.  Twice, so you’re 100% sure of getting it right.

This measurement is the diameter of the circle.  Divide it in two to get the radius.  We’ll call this measurement “R”

Now calculate the area like this

Area = R x R x 3.14

For a circle that is 6 metres at its widest point

The calculation looks like this

Radius (R) = 6 m ÷ 2 = 3m

Area = 3 x 3 x 3.14 = 28.26 square metres (keep it simple and call it 28 m2)

You will need 28 m2 x 0.03 Kg = 0.8 Kg of grass seed.   A 1 Kg pack should be just fine.

Where to buy grass seed

Be wary of cheap grass seed – it may not produce the lawn of your dreams.

The grass seed available from Turfonline is a similar blend of species to those used by UK turf growers.  It’s less than one year old so you can be confident that it will germinate quickly and grow strongly to give you a great lawn in next to no time.

View our seed range here

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