Module 4:

Materials

4.4 How much is needed?

4.4.3 Grass seed

A football pitch has only been lightly used during the playing season. Only the central strip of 2,500m² needs to be overseeded at a rate of 17g/m².

What is the total quantity of grass seed that is needed for this central strip?

1. Do you need some initial help with the calculations?

There are 1,000 grams in 1 kg.

If the application rate was just 1 gram for every square metre of pitch then the requirement would be 7,000 grams of grass seed for a full sized pitch of 7,000².

The question says that it is only the central strip of 2,500m² that is to be overseeded, so at 1 gram per square metre this would require 2,500 grams, or 2.5 kg, of grass seed.

Hopefully this helps you do the calculation to work out what would be required for the required amount of 17 grams for each square metre of of the central strip.

2. Do you need some more help with the calculations?

We have shown that for the central strip of 2,500m² a rate of just 1 gram for each square metre would require 2,500 grams, or 2.5 kg, of grass seed.

The question has asked for 17 grams of grass seed being required for each square metre of this central area.

If it was 10 grams per m² needed then the total would be 25kg (that's out 2.5kg multiplied by 10), but it is 17 grams that is needed.

Can you now work out the final quantity that is required?

3. Do you need some other help with the final calculation?

We need to muliply our initial calculation of 2.5kg by 17 to give us the correct amount. Therefore 2.5kg x 17 = 42.5 kg.

There can be several ways to arrive at a correct answer, but hopefully the above approach has been clear

1 Renovation time is when most grass seed will be used. If, however, everything is fine, with good grass coverage and desirable grass content due to minimal usage then there might not be any requirement for an overseeding to take place. This is an unlikely scenario, but it can occur, and groundskeepers should not automatically assume that full material requirements are always needed.

2 Typical applications rates are:

17-35 g/m² for thin swards to bare areas.
35-50 g/m² for significant bare areas in a pitch and those surfaces that have been stripped clean.
Higher rates might sometimes be used for a quicker initial coverage, although care needs to be taken to ensure adequate air flow is maintained amongst the denser young sward to reduce the likelihood of disease attack.

For grass seed inclusions in a divot mix, then this might be one or two handfuls of seed per hand bucket.

3 There are many brands to choose from, along with many different types (cultivars) of a particular grass species as well, but the main species will be Perennial ryegrass, typically with two or more cultivars within a seed bag.

An example is Masterline PM80 Renovator Grass Seed (20kg) with 4 cultivars of Perennial ryegrass: this has a guide overseeding rate of 25 - 75 g/m².

For a well-worn 7,000m² pitch at renovation time and at a rate of 50g/m² this would require 350kg of seed. A rate of 35 g/m² (requiring 245kg) in early May should usually be a suitable rate to enable a well-established sward to develop over 10-weeks before an August start date.

Module progress: 72%

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