Having evolved through grazing, grassland relies on a late annual cut to prevent encroachment of scrub. But cattle and sheep are not always the practical option

A tractor with a flail mower or topper will cut the vegetation but a thatch of cuttings is left which obstructs the growth of all but the most vigorous plants. Also, as the cuttings rot, they return nutrients into the soil, increasing its fertility and allowing aggressive nettle, thistle and dock to smother the wild flowers.

To combat these problems hay cutting and baling year on year reduces soil fertility, as nutrients are removed when the plant matter is collected. Over time, this helps improve biodiversity.

The timing of the cut is important; traditionally hay was cut from the middle of July onwards, allowing most flowering species to propagate by seed. Late-flowering species such as greater knapweed and clustered bellflower can benefit from a cut as late as September.