Many trees and shrubs can be grown from hardwood cuttings, roses being one of the most common examples. Exactly as you’d expect, hard wood cuttings are lengths of woody stems covered in bark and usually planted in the dormant season when leaves have dropped between late-autumn through to late-winter. Every year I cut back my Sambucus nigra f. porphyrophylla ‘Black Lace’ and Buddleia davidii ‘Santana’ to the ground giving me plenty of material to take cuttings. Others plants to take cuttings from include Philadelphus, figs, gooseberries, Cornus and many more.
Hard wood cuttings cannot be easier. All you need is wood of at least a pencil thickness with leaf nodes at the top and bottom of each stick. Length depends on the plant but generally should be about 20cm long. Which means on some plants you will have lots of leaf nodes in the middle too, while on others (like Sambucus above) the spacing is wide enough to simply have nodes at each end.
Cut closely beneath the bottom nodes at a flat angle and just above the top nodes at a diagonal. The main reason for this is to make it easier to remember which way is up, it sounds obvious but sometimes it’s hard to tell when the cutting is no longer on the plant. It also helps rain run off the top wound preventing rotting.
Armed with your propagation twigs you then just stick them in the ground burying two thirds deep, leaving only the top third above ground. Next year you will see leaves start growing again and by the end of summer, they should all have developed roots along the stem beneath the ground ready to be grown on elsewhere. Leave about 15cm of space between them. I plant them in the ground in a row on my allotment but until I am back down there, I’ve plonked them in a temporary pot (above) with some sticking out a little too far because of their length.