There are two methods of establishing a grass ley; undersowing and direct reseeding. With the advent of winter cereals, which are harvested some weeks earlier than spring crops, direct reseeding allows for the successful establishment of a grass ley before the onset of winter. This method does rely on sufficient rainfall to aid establishment at the crucial time. Non the less, it is a well practiced method nowadays.

Leys are most usually mixtures of grasses and clovers which provide grazing or cutting. This depends on their purpose and the requirements in each situation. For example, they may lie for one or two years, usually intended principally for cutting. They may also be designed to lie for three to six years, these are usually intended for both cutting and grazing. Also, so called permanent pasture may lie for up to ten years or even longer and are specifically designed for that purpose.

The traditional method of establishing a ley is undersowing, most usually a spring cereal crop. This has the advantage, if growing conditions have been reasonable, of providing an already established ley after the cereal harvest. It is advantageous to reduce the cereal seed rate slightly and also reduce the nitrogen application slightly in the seed bed. This aids the successful establishment of the grass ley by allowing better access of sunlight to the developing sward.

If a wet harvest is feared the crop can be cut early at the soft cheesy stage as wholecrop silage, which will avoid damaging the establishing sward. This also allows the sunlight into the young grass and clover plants these few weeks earlier thus benefiting the sward immensely.

This can provide early autumn grazing by cattle or more usually sheep. This light grazing leads to increased tillering of the young plants improving density of the ley for the following season. This late season grazing is ideal for finishing lambs and can be particularly appropriate for flushing ewes before tupping.

The undersown sward can incidentally offer excellent over wintering cover thus allowing insects to complete their lifecycle in the soil, ready to emerge in spring as adults subsequently providing feed for game chicks. Additionally, the undersown sward supplies nutrients and water retention. It also helps to control weed invasion.

Altogether undersowing a grass ley is still a highly desirable practice offering many extra benefits.