The Gardening Year for Shrubs
Spring
Plant shrubs in prepared ground or in containers in early spring, or as soon as weather conditions permit. Feed and mulch established specimens and prune deciduous plants that need renovation. Shrubs such as the butterfly bush (Buddleja davidii) and Chinese plumbago (Ceratostigma willmottianum), which flower on new growths made during the current season should be cut back in early spring to give them plenty of time to grow new shoots before flowering. Shrubs that are grown for summer foliage or winter stems (e.g. dogwood) should be coppiced or pollarded. Take softwood cuttings for propagation and divide suckering shrubs.
In mid-spring, carry out formative and renovative pruning of evergreen shrubs. Pinch out ('stop') the principal leaders of shrubs you wish to keep dense to encourage the development of sideshoots and a bushy habit. Sow seeds of tender shrubs undercover, ready for planting out in late spring.
In late spring, carefully deadhead flowering shrubs, unless seed is required. Prune back any spring-flowering shrubs after the display of blooms has finished. Any suckers and reverted shoots should be removed. Greenwood cuttings may be taken for propagation, and simple, tip or mound layering may be carried out.
Summer
Water shrubs well; those in containers may also need to be fed. Carry out regular deadheading throughout the season, unless the seed-heads are needed for decorative purposes, or for the seeds themselves. Prune shrubs that flower on old wood (e.g. lilac and Philadelphus) once they have finished flowering, so that there is plenty of light to ripen the growths made during the summer.
Soft tip and semi-ripe cuttings may be propagated in mid-summer; keep the cuttings in a bright (but not sunny) place until they are rooted. This will take two to three weeks.
In late summer, trim away the first spent blooms on buddleias, so that the secondary flowers appear cleanly on the bush. This is the time of year that propagation by chip-budding and side-grafting can be carried out on deciduous shrubs.
Autumn
In early autumn, prune evergreen hedges and renovate any deciduous shrubs. New shrubs may be planted out in mid-autumn, and any established shrubs that need to be moved may be transplanted. Although evergreens may be moved at any stage during the autumn, wait until deciduous plants have lost their leaves before transplanting.
Leaf-bud cuttings may be taken in early autumn and hardwood cuttings in mid to late autumn. Propagation may also be carried out by simple layering at this time of year.
Cut away all dead, diseased, and damaged wood in late autumn. Protect tender or half-hardy shrubs by providing them with insulation or by bringing them under cover.
Winter
Continue formative pruning and renovation of deciduous shrubs during the early part of winter and ensure that all dead and damaged wood has been removed.
Evergreens and deciduous shrubs may be planted, as long as the soil is not too cold.
Shrubs may be propagated during the winter by layering or by apical-wedge, saddle, and side-veneer grafting. Hardwood and root cuttings may also be taken.