late January – February: soft-tip cuttings of tender perennials overwintered under glass
March: soft-tip cuttings of tender perennials as new growth extends, such as Fuschsia
April-May: soft-wood cuttings of late-flowering deciduous shrubs as their new growth extends, such as hydrangea, buddleja and Hibiscus.
June: no cuttings
July-August: semi-ripe cuttings of deciduous shrubs after flowering, such as Philadelphus and Rosemary.
August-late September: semi-ripe cuttings of evergreens such as Hebe, Skimmia
October-December: hardwood cuttings of deciduous trees and shrubs such as willow (Salix), Buddleja, Prunus, currants and gooseberries.
Nodal: cuttings are made by trimming the stem just below a single or pair of leaves or buds. Rooting hormones naturally accumulate at nodes so this is a good method.
Internodal: Cleanly trim the butting between the nodes or leaves. This is successful with many easy-to-root plants propagated as soft and semi-ripe cuttings. Particularly useful for climbers like Clemantis and Lonicera (Honeysuckle).
Heel: Reliable option for evergreens and thin-stemmed deciduous shrubs such as Ceanothus and Pyracantha, by taking cuttings with a ‘heel’ in late summer. Cutting made by gently pulling a ripening sideshoot away from the stem, retaining a small amount of tissue from the parent stem. This should be cleanly trimmed to 2-3 mm before inserting the cutting into potting soil and grit.
Basal: A basal cutting is made from shoots that emerge from the crown of a perennial in spring. A recommended method of propagation for herbaceous perennials like lupins, and delphinium. The emerging shoot is removed as close to the woody crown as possible to ensure the cutting base is firm and has enough substance to sustain the cutting during rooting.
Wounding: Improve success with semi-ripe cuttings by wounding the cutting by removing a 2-3 cm (1 inch) sliver of bark from one side of the base of the cutting. This exposes a larger surface area for the stem to absorb moisture and rooting stimulants.
There is an extensive article on taking cuttings of all kinds, including advice on the use of heated propagators, in The Garden, RHS, April 2013.