Perennials are considered the mainstay of the mixed borders. Though some are short-lived, most live for years increasing in number. Each winter they die down, then spring comes and up they spring.Some bloom just once and briefly, while others may bloom, if dead-headed (removing the spent flowers), for months and months. Although there are perennials you never disturb, for example – peonies; most, however, need dividing every few years.
If you only have one mixed border, you probably would like to have flowers throughout the growing season. Choose plants that are lovely for more than just a week or two. If there are any gaps (no blooms) in the border, you can fill with annuals or other flowering plants in pots. Flowering shrubs and remontant (repeat blooming) roses add color to the background.
The border should be at least 10 feet wide. The plants should be planted in drifts of odd numbers . The plants should vary in height from low to high. To keep the border from looking like a stairway to heaven , vary a few drifts throughout the border with a drift of shorter plants in back and a drift or two of taller plants in front.
You may have borders using all types of color schemes. If you have 2 borders, you may choose to have one border of cool colors, and one border of hot colors. You may also have the border begin with cool colors and gradually increase the intensity of color until the other end has hot colors. Some people enjoy doing their borders with just once color, using different shades and tints. Some are happy with using two colors of which they may be two complementary colors, such as red and orange, or contrasting colors, such as red and green.
Many people use three or more colors. Using color is a tricky thing with plants, particularly if you use different seasonal color schemes. Out of the blue two plants that are neighbors and should not bloom at the same time all of a sudden clash, because of strange weather. Use color to achiever unity. At the same time, shake things up a bit to create tension. This is a fine line. But all borders need a touch of pizazz to arouse your neighbors’ envy to shades of green.