Always choose healthy, well-grown plants and plant after autumn rains. Before planting, ensure the root ball is saturated and remove the planter pot with minimal root disturbance. Trim any broken roots and plant at the same level as in the container. Dig a hole twice the diameter of the root ball, press in and water once planted. Make sure the plants are watered well until established if planting in a drier period. Plant with some general slow-release fertiliser. After this, apply organic fertiliser, such as blood and bone, at a handful per square metre, in spring as new growth appears.
Planting too closely leads to spindly growth, poor flowering and eventual plant decline. In a well-planned border, the plants in flower should just touch each other to create a full effect without overcrowding. Plant approximately 50cm apart. Slug bait may be needed as they are very susceptible to damage.