Cuttings should be taken in the middle of winter.
The cuttings should be about the length of your thumb and no more than about 5mm in diameter.
Avoid the fresh sappy growth and any flower buds (the larger fat buds).
The propagating medium should consist of the following;
1 part sand (coarse river sand)
3 parts perlite
2 parts peat
The cuttings should be kept in warm conditions – preferably in a hot house. Keep media moisture levels to a minimum. If too much water is available, the cuttings won’t have any need to develop roots. Different varieties will have varying degrees of success. 'Northland' in particular has a very high strike rate.
With thanks to Paul Winfield