Prepare the planting site when soil is moist and easily worked after the first rains in autumn. This way, the soil is still warm so the plants can make root growth before the following summer. Always choose healthy well-grown plants. Remove all perennial weeds and incorporate bark compost or other organic material. On heavy soils, raise the level of beds and borders with extra topsoil and coarse pumice sand. Plant when the soil is moist and warm in autumn or early spring so that a good root system develops to support vigorous new growth. Before planting, ensure the root ball is saturated and remove the planter bag or 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 put in the plant and firm around the base water in well.
They benefit from a weed-free, well-drained soil rich in organic material. Planting too closely leads to spindly growth, poor flowering and eventual decline. In a well-planned border, the plants in flower should just touch each other to create a full effect without overcrowding. Apply an organic-based fertiliser such as blood & bone at a handful per square metre in spring as new growth begins. Control slugs and snails to prevent damage to tender young shoots.
Bedding plants are usually raised from seed sown under trays under cover. The seedlings are transplanted into small containers for growing before finally being planted out. Transfer seedlings outdoors to be hardened off before planting. Soil should be friable. Prior to planting, rake general-purpose fertiliser into the soil at about 100 grams (about 2 handfuls) per square metre. Plant at the same depth at which the plants were growing in their container, as planting too deeply usually results in failure. Handle carefully to minimise root disturbance.