Answer: There are only a few rules to follow when pruning. 1) prune flowering shrubs immediately after they have finished flowering. 2) don't remove more than one-third of the live plant material in any pruning session.
Your Hicks Yew can be sheared back by 2-3" to encourage a dense, bushy shrub; lilac flowers can be snapped off as soon as they are spent. Lilacs develop flower and leaf buds during the summer months for the following spring's floral display so prune immediately after flowering so the plant has a chance to develop new flower buds. Weigela can be pruned back hard after flowering. Cut out errant stems and shape the plant any time during the summer months. Maple trees are best pruned when they are dormant (winter months); cottoneaster can be pruned back hard in the spring to keep it in bounds; deadhead the spent flowers on Lady's Mantle. If it is very overgrown, twist off some of the largest stems and plant them elsewhere in your garden; hydrangea flowers can be pruned off when they are spent, ditto with astilbe flower stalks. Vinca usually doesn't need any pruning, nor do hostas. Climbing roses develop flowers on new shoots which develop on old wood. You can shorted some of the longest canes to keep the plant tidy and to promote flowering.
Best wishes with your garden!
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