Insert the cuttings vertically into the holes, leaving about one third of their length above ground. Keep a fair distance between them so once they rooted they may be lift individually without disturbing the other ones. Firm and water the soil around them. After frost, which may loosen the roots in the ground, refirm the soil.
Another option is to root hardwood cuttings in deep pots with light, sandy soil. Plunge the pots in soil or sand in a shady outdoor site and water them as needed.
Semi-ripe cuttings may be more successfully than hardwood cuttings in areas with severe winters. In early autumn, after flowering, select mature sideshoots that are still green. Take 15 cm lengths, cutting above a bud where the shoot begin to turn woody and trim off the soft tips. Prepare cuttings about 10 cm long and than follow the same procedure as for the hardwood cuttings.
Insert them into deep pots of sandy compost – equal parts peat and sand. Cover the pots with plastic bags or put them in a propagator to prevent the cuttings from loosing moisture, in a frost-free place. In spring plant out the rooted cuttings in a nursery bed.