Wind is a climactic factor to consider in deciding on a location for perennial plants. Strong winds and heave rains can cause severe damage to tall perennials. Staking tall plants reduces this risk. A hedge of moderate height or a planting of shrubs provides protection and supplies a pleasant green background. Although some perennials are adapted to most locations, most require a well-drained soil.
Poor drainage encourages root diseases and increases the hazard of winter killing.
Sloping land does not necessarily indicate good drainage. The subsoil should be open and porous. Soil preparation should be thorough because the border is permanent and the plants grow in the same ground for a number of years. The soil should be deeply dug, incorporating manure, compost or other decayed organic matter, to improve the physical condition. This year I'm going to try a new perennial soil mix from Berger.