Used as border backgrounds and in situations where a plant adds contrast to a structure such as a wall, tall perennials have a function in the garden landscape. Those that feature red flowers stand out even more when in bloom and work well in flower, perennial and cottage gardens.
Annuals that grow rapidly enough to become tall and that have red flowers are not plentiful in number, but some exist. One is the sweet pea, some of which produce red flowers. With support, this annual takes the form of a vine, growing to 8 feet in full sun. Another tall annual is the sunflower, with red hybrids that grow so quickly there is no necessity to start the seeds inside. Sunflowers can sprout up to 10 feet high and work well in cottage and native plant gardens. Mexican sunflowers, possessing red-orange rays surrounding a central disc, are also good fits in the backgrounds of garden borders. They mature to 6 feet in a single growing season.
The trumpet honeysuckle vine, able to grow to 20 feet, turns out red flowers with a tube-like form. Alabama crimson is a noted hybrid with red flowers that contrast sharply with the plant's bluish-green foliage. Clematis vine species like My Angel and Indian Summer have red flowers. Vines such as cypress vine, glory bower and lipstick plant bloom red. Atrosanguinea is a hybrid of the cross vine with deep reddish-purple flowers. The vine grows to 30 feet long on a garden trellis, blooming during May and June.
Gardeners who enjoy yarrow have the Red Beauty hybrid for use as a tall perennial. Its red flowers emerge in flattened groups. Cottage gardens from USDA Plant Hardiness zones 2 through 8 are suitable venues for hollyhock, a perennial growing to 8 feet and producing red flowers and heart-shaped leaves. Lord Baltimore and Southern Belle are hybrid varieties of the hardy hibiscus capable of growing to 6 feet. Sacred lotus, cardinal flower and the scarlet rose mallow all grow to tall stature and have red flowers. Cardinal flower cultivars such as Queen Victoria are perfect for wet areas of a woodland garden.
The versatility of the Florida azalea allows its use in sunny or shady spots, including open shade and woodland gardens. This deciduous shrub grows to 10 feet in zones 6 through 9, with red cultivars available on the market. The Chinese shrub Moyes rose grows between 6 and 10 feet high, has deep red flowers and tolerates salt spray, making it a possibility for seaside gardens. Large-flowered climbing rose species such as Don Juan and Blaze Improved are tall and have red flowers. Both are suitable for planting in cottage gardens.