Planting step by step: helping the plant establish
Timing, watering, mulch. Three things it all depends on. No waffle.
Plant at a suitable time (spring or autumn), not in the worst heat. Soak the root ball before planting, make the hole slightly larger than the pot, and water well after planting. In the first season, water until the plant has established.
For professionals
Container-grown perennials can be planted throughout the growing season, ideally outside periods of high temperatures. If the root ball is pot-bound with circling roots, score it so that the roots do not stay coiled. Mulch (3–5 cm) reduces evaporation and weeds; do not pile it up against the crown. In the first year, water at the roots, less often and generously.