If you are taking your own slips/cuttings do try these 2 rooting hormones. Make a weak honey solution. It's as simple as that! The other is a Willow bark tea. You can use the alien invader, Salix babylonica or our own Salix mucronata. Scrape about 1 T of the bark off the tree, put it in a pot of water, about 1 litre and bring to the boil. Allow to steep over night. Dip your cuttings into this solution before putting them into riversand/compost mix.