Landscapes used to be filled with shrubs that could easily reach small-tree status if not harshly pruned.

Forsythias, mock oranges, lilacs, burning bushes, PeeGee hydrangeas, Chinese fringe flowers, rose-of-sharons, and butterfly bushes are some of the old-fashioned favorites that can grow into rangy bushes of eight to 10 feet or more.

Then people began buying bigger homes on smaller lots. And aging retirees and working couples with kids both found they had less energy and time to devote to landscape-trimming duty.

The result has been an increase in demand for smaller-sized and slower-growing shrubs – ones that stay more in the three- to four-foot range.

The trend toward shrunken shrubs

Some shrubs are naturally more compact than others. Azaleas, potentilla, globe arborvitae, spirea, St. Johnswort, and leucothoe are examples of species that never grow much bigger than four feet tall and/or wide. These have long been popular choices for smaller yards.

However, in response to the growing demand for smaller plant choices, plant breeders have focused lately on developing more compact versions of classic but bigger species.

So-called "dwarf" varieties can come from several different techniques.

The oldest is watching for plants that turn out to be smaller than the norm for that species – akin to that one brother who is markedly shorter than the rest of the family. Like people, plants have variability both in their genetics and how they respond to environmental stresses, such as cold, light, and disease attack. When cuttings are taken from these plant exceptions, the offspring often grow with the same exceptional traits.

Sometimes growers and keen-eyed gardeners notice even more extreme exceptions or "mutations" that make a huge leap in size or other traits (i.e. an odd leaf color or a weeping growth habit). Cuttings from these often end up as the genesis of a new and unusual plant variety.

Growers also can purposely induce changes, such as by introducing a stress or by cross-pollinating flowers from two or more different plants.

Grafting is yet another way to produce dwarf varieties. That occurs when the branch of a desirable bloomer is attached to the rootstock of a variety that’s naturally smaller or slow-growing.

Finally, breeders can use genetic engineering in which they insert (or remove) genes that control the way in which a plant grows.

How to use compact shrubs

The many new short-and-squat shrub varieties aren’t just for maintenance-challenged gardeners. Smaller sizes make good design sense in a variety of settings.

Limited spaces are logical sites for compact plants, such as underneath windows, in narrow beds between the porch and sidewalk, and in foundation beds that are only three or four feet wide. These are places where hulking hollies or bulky burning bushes will lead to unnecessary trimming that's not ideal for the trimmer or the plants.

Compact shrubs also are useful when mixed among perennials and ornamental grasses in garden beds, when planted in front of taller shrubs or hedges in a border bed, when planted on either side of a taller specimen plant, and when used as spots of color along walks, patios, and decks.

Compact shrubs make good choices for growing in containers, too.

Keep in mind that the word "dwarf" on a label or plant name doesn’t necessarily mean the plant is little. While most dwarf shrubs grow three to four feet tall or less, a plant can qualify as "dwarf" so long as it’s smaller than the species' norm. In other words, a "dwarf" oakleaf hydrangea might still grow five or six feet tall, which is more compact than the eight-foot height that’s typical in a mature straight-species oakleaf hydrangea.

The lesson: consult labels and plant descriptions for the size information of the specific plant you're considering and use that when planning your spacing.

Five good compact shrubs for sun

Interested in shrinking your plant sizes? Here are five worthy flowering shrubs for full-sun sites or those that get at least six hours of direct sun a day:

Five good compact shrubs for shadier spots

Gardening in lower light? Here are five worthy shrubs (all U.S. natives) for sites in shady to partly shady sites: