After the first autumn frost plants begin to transport nutrients to the rhizome and the above ground plant start to dry and leaves eventually fall. Canes dry out through the autumn and winter months and achieve a moisture content of between 20-40% at the end of the winter. At this stage the crop can be harvested using a mower conditioner and baled when field conditions allow.

Harvesting and Storage

The crop should be harvested annually between January and March. It is cut with a mower conditioner and allowed to dry in the field and then baled, ideally into rectangular ‘Hesston’ bales, which are easily transportable. Bales are stored in the dry or stacked and sheeted outside as the drier the crop the higher the bale value as it provides more energy when burnt.

Yields in the establishment year are low as the plant expends energy in developing its root and rhizome base. Miscanthus reaches its potential production in the third or fourth year under adequate conditions. Mature crop yields generally vary between 18-25 t/ha/yr dry matter in Europe, whereas across the UK, the European Miscanthus Productivity Network have reported yields up to 16.6 t/ha/yr dry matter. The energy content of the dry above ground fraction of the plant is 18.4 MJ/ kg.

Once planted, miscanthus is productive for at least 20 years (although the oldest sites in the UK and Ireland are still only 12 years). After the establishment phase (2-3 years) it is possible to harvest miscanthus rhizomes for sale, this typically leaves enough rhizomes behind in the soil for the crop to re-establish. Removal of a miscanthus crop is simple and similar to the process of removing short rotation willow coppice – wait until first growth in spring, apply glyphosate and then plough. Within one year the area can be re-sown for grassland.