Start planting or sowing hardy perennials in prepared ground in early spring, as soon as weather conditions permit. Herbaceous perennials may be lifted and divided at this point. Feed and mulch established perennials and water new plants as necessary.

In mid-spring, remove dead growth of half-hardy plants and cut back shrubby perennials. Any tender plants may be brought outdoors on mild days to harden off; bring them under cover if frost threatens.

In late spring, thin out dense shoots and 'stop' (pinch out) any plants that need to be encouraged to produce side shoots and develop a bushy habit. Provide supports for tall plants or climbers. Repot or top-dress plants in containers.