Module 8:

8.4 Creating an annual maintenance schedule

8.4.3 How much does grass grow in a day?

1   A good question and there is no straightforward answer because there are many variables affecting rate of growth.

Grass growth is going to vary throughout the year depending on a lot of influencing factors, including but not limited to temperature, available water, daylight, shade cast on the pitch, fertility of the soil, grass species and cultivars present, and other factors.

Perennial ryegrass is usually the main turfgrass species used on football pitches. If we say a very general and simplified guide figure for maximum growth is 10mm per day, which might typically occur during May. This might be more where high fertility levels exist, combined with plenty of available moisture, optimum temperatures and light levels, as well as the particular cultivar used. However, this guide figure is very subjective but can start to help us provide some suggestions for mowing frequency.

2   Frequency of cut

Grade 3 standard:

1.   Maximum allowed grass height = 60mm.
2.   Mower setting = 40mm if it is to be 1/3rd of the maximum allowed height.
3.   Maximum growth allowed above the mower setting = 20mm.
4.   Grass growth rate (May) = 10mm per day (illustrative only).
5.   Frequency of cut in days = Maximum growth ÷ growth rate (20mm ÷ 10mm) = 2.
6.   Frequency of cut each week = 3.5 occasions (for May, based on above data).

3   From a practical perspective the pitch might then be cut Monday, Wednesday, Friday and on Saturday at the match day setting. This assumes the first weekend match is on a Saturday.

Even if a pitch was a grade 2, and if the grass was planned to be cut when it reached its maximum height of 70mm then 1/3rd of this height is 23mm, which would still mean the pitch needing to be cut every 2¼ days or on 3 occasions per week in practice. For example, this might be Friday or Saturday as being the match day setting, then cut again Monday and then later on Wednesday.

We suspect that many grades 2 or 3 pitches are not cut to the required frequency that enables the grass plant to maintain itself in a strong condition. Where growth is a lot more rapid then mowing frequency would need to increase (which probably rarely happens in practice for many grassroots pitches) and where growth is slower then mowing frequency would decrease.