Getting plants to flower isn't difficult. The secret is understanding their needs and giving them what they want. Since plants' needs vary considerably, depending on the species and even the variety, a good gardening book is an indispensable resource. Once a plant's needs are met, patience usually is all that is required.
All flowering plants have a predetermined time for blooming that can't be manipulated or altered. Most annuals bloom all summer long, while bulbs bloom for a short period in the spring, summer or fall, depending on the bulb. Perennials vary in their bloom time--some bloom all season, while others have a short window of flowering. Varieties of the same species may bloom at different times. For example, jackmanii clematis blooms mid summer, while C. paniculata clematis doesn't flower until early fall.
Most flowering plants need at least six hours of sunlight daily to flower well, although a few such as vinca, hosta and impatiens thrive in partial shade. Many perennials, such as daylily, Jupiter's beard and salvia flower in either condition, but produce more blooms in full sun. Flowering plants need adequate moisture and fertility to bloom properly. Roses, hydrangeas and fuschias, especially, need plenty of water to produce flowers. Flowering vegetables, such as tomatoes, peppers and cantaloupes need warm, moist conditions, although if temperatures are too hot, they drop their flowers and don't set fruit.
Some plants are self-cleaning, meaning spent blossoms drop to the ground and new blooms form. Others benefit from "deadheading," the practice of removing spent blossoms so new ones can emerge. Many, such as coreopsis and salvia, are self-sowing and will produce new plants wherever seeds are dropped. Plants suffer some transplant shock when first planted, and may initially stop blooming. With plenty of watering, though, they quickly rebound. Additionally, most perennials benefit from being divided every three to four years. Division invigorates plants and encourages new growth.
Climate affects when and how prolifically plants bloom. Perennials in southern gardens bloom much earlier than the same plants grown in a northern garden. Additionally, some plants, such as passion flower, that grow as perennials in mild climates are treated as annuals in colder areas. Mulching plants provides winter protection and allows the soil to warm up earlier in the spring so plants emerge sooner.
Good soil preparation is a must for perennial beds, according to Barbara Damrosch, landscape designer and author of "The Garden Primer." These plants are long-lived, remaining in the same plot for many years. Adding peat moss, compost and manure to the soil and digging it to a depth of at least 12 inches provides perennials the well-drained, nutrient rich soil they need to grow and bloom.