Those who need to fill in sparse areas quickly usually desire fast-growing trees. There are various fast-growing trees available. Some are strictly ornamental, some provide dense shade and others act as a privacy barrier. The quick growth also sometimes has a downside, as some of the trees are prone to wind damage because of large, brittle branches and shallow root systems.
The fast-growing Lombardy poplar grows 6 feet or more a year. The tree's leaves face upward instead of spreading out. This tree requires full sun and much water. Plant it away from septic lines and water pipes because the Lombardy poplar will seek out the water with their roots, invading the pipes and lines. Lombardy poplars are often planted in rows, along fence lines and driveways for privacy and as a windscreen. This tree grows up to 100 feet high and has a lifespan of about 80 or more years.
This highly fragrant shade tree is a favorite food for Koala bears in Australia. Requiring a hot, dry climate, it also grows in areas of the Western United States. The tree grows to about 40 feet in height at the rate of about 6 feet per year. The Eucalyptus tree remains attractive throughout the year, never losing its blue-green leaves. The aromatic leaves work as a natural flea repellent and are a showy addition to floral arrangements.
October Glory Maple
This tree grows to a height of 40 to 50 feet at the rate of about 2 feet per year. The October glory maple produces profuse, tiny, red flowers in the spring and glossy, green leaves in the summer, changing to deep red in the fall. The tree prefers full sun to partial shade and although drought tolerant, it loves water. October glory maples are hardy in USDA Hardiness Zones 5 to 8.
The Cleveland pear is a small-to-medium, ornamental tree that quickly reaches a height of up to 40 feet. It average 3 to 4 feet a year in growth. The tree grows in a symmetrical shape and requires little pruning. The Cleveland pear is often used to line roadways and as a front yard feature. The tree produces a mass of creamy white flowers in the spring and has showy, scarlet red fall foliage. Cleveland pear trees grow best in full or partial sun and in fertile, well-drained soil. This tree is hardy in USDA Hardiness Zones 5 to 8 and is disease resistant.
The fastest-growing tree in the United States, the cottonwood is also one of the largest hardwood trees at up to 100 feet high. The cottonwood has shimmery leaves, which change to bright yellow in the fall. It is susceptible to many diseases and insect invasions. The cottonwood provides vast shade and is tolerant of most conditions. The tree does seek water so is not good for areas where it has access to water lines or septic systems. Cottonwood trees are either male or female. The tree got its name from the fluffy, white seeds produced by the female tree in early summer. Cottonwoods live up to 100 years. The tree is widely grown in the Western United States.