A new home, new neighbors, or a new swimming pool in the backyard can leave you wanting a privacy hedge in a hurry, but many of the densest formal hedge plantings can take many years to grow into shape. Select the fastest-growing privacy hedge shrubs or trees to create a quick screen between your property and nearby eyes or noise, and consider interspersing them with slower-growing, more-preferable varieties to create a longer-lasting solution.
Like the thorn bushes grown around a fairy-tale castle, prickly hedge shrubs not only screen unsightly views, they can help improve your property's security by acting as a barrier to intruding animals and people. Pyrancantha grows 10 to 12 feet high within 2 or 3 growing seasons, bears a profusion of bright-orange berries in late autumn, and is covered in nasty thorns. The five-leaved aralia ("Acanthopanax sieboldianus") grows to 9 feet high after 3 or 4 years, even in poor soil conditions, and is also quite thorny. Barberries ("Berberis spp.") and hawthorns ("Craetaegus spp.") also grow quickly into dense, thorny, compact masses, each producing berries in autumn that attract birds, and can create a 3-foot-high hedge within a few years.
Evergreens grow more slowly than deciduous bushes, taking 5 to 7 years to create a 5-foot-high hedge, but they have the advantage of continuing to block the view, noise and wind all through the winter months. Among the fastest-growing evergreens for hedges are the Sawara false cypress ("Chamaecyparis pisifera") and the American arbor-vitae ("Thuja occidentalis"). Eastern red cedar ("Juniperus virginiana") also makes for a fast-growing hedge, and is adaptable to less-than-ideal soil conditions. Allowing hedge shrubs to grow up quickly, however, may result in sparser growth than you might wish for. Cutting off up to half the growth of your hedge shrubs each year for the first several years will create denser, bushier plants for the duration of your hedge, according to the University of Florida IFAS Extension.
Flowering shrubs combine the benefits of a deciduous privacy hedge with those of perennial flower plantings. Common lilac ("Syringa vulgaris") has long been favored as an informal homestead hedge across much of North America. Forsythia is fast-growing, hardy, and blooms with a fountain of yellow flowers in midspring, about the time that tulips bloom. Pruning keeps the sprawling forsythia tamed, while suckers springing up between the original shrubs keep the hedge dense and constantly renewed, according to the University of California Extension. Forsythia will create a 5- to 6-foot hedge in 2 to 3 years depending on growing conditions. A number of species of viburnum also create flowering hedges, followed by berries that attract birds and other small wildlife. Sweet viburnum ("Viburnum odoratissimum") thrives in sun or shade, while "Viburnum plicatum tomentosum," or double file viburnum, maintains a horizontal habit. Viburnum are more open in habit than forsythia, so growth rate depends on how much you cut them back to make them denser.
Fast-growing trees with low-growing branches, such as lombardy poplar and cottonwood, can create a privacy screen and a wall of shade in just a few short growing seasons. The problem with these fast-growing trees is that they're not long-lived, and tend to break in the wind or fall prey to insect infestations. A solution suggested by the Virginia Cooperative Extension is to interplant slower-growing, more-permanent trees between faster-growing specimens, removing the latter to make way as the former reach adequate heights and fullness for screening. Hedge maple and Canadian hemlock have long been recommended by the Arnold Arboretum as trees that can be successfully sheared and pruned into a low, dense privacy-hedge shape. These trees may take 7 years or more to form a tall, thick hedge.