For healthy plants with strong root development and profuse bloom, proper bed preparation is essential. Aim to achieve good soil drainage and fertility at the outset. 

First, remove all plant cover such as turf and weeds by digging and cultivating. Any weeds with persistent underground parts may need repeated effort, or non-toxic methods. Then dig the bed to a depth of 6 inches for annuals and between 8 and 10 inches for perennials. This encourages the plants to root deeply and establish well from the outset.

Work compost into the soil to both improve drainage and hold moisture in the bed before planting. 

Courtesy of the NYBG Plant Information Service