When developing a garden design, we draw from many types of cultivars as well as native plants to create a healthy, diverse landscape. Using cultivars gives our landscape architects a much broader aesthetic palette to work with. And, most importantly, gives us a wider range of plants that will adapt successfully to our Mid-Atlantic climate zone.
What Are Cultivars?
A cultivar is a “new” version of a plant that has been selected and cultivated to reproduce one or more desirable traits of the original. Growers propagate cultivars from cuttings taken from the origin plant.
For example, if a grower discovers a particular plant that blooms longer than others of the same variety, they’ll take a cutting and try to reproduce it through propagation. Or, they may select and propagate a spring blooming plant that displays a few weeks later than others of its variety. They will breed that late bloomer to produce a cultivar that avoids the possibility of a late season frost.
On the practical/functional side, cultivars are frequently bred for pest and disease resistance, drought tolerance, or to accept a wider range of temperatures and humidity.
In recent years, growers have also developed “dwarf” versions of popular shrubs and trees that take on a more compact form and fit into landscapes with space limitations.
Why do we use cultivars in garden design and landscaping? Here are eight good reasons:
- Consistency of growth habit and form
- Dwarf and compact varieties to fit small spaces
- More flower color and foliage options
- Extended bloom times
- Ability to thrive in wet, dry, salty, or low nutrient soils
- Disease and pest resistance
- Drought and cold tolerance
- Shade and sun tolerance
Cultivars Bred From Wild Species
When the mother plant is a native, the cultivars are considered native plants as well. Sometimes cultivars of plants native to a region are referred to as “nativars.”
The dogwood cultivar “Appalachian Spring” is a good example of one that was developed from a native plant that stood apart from others in its variety. It was developed from a wild dogwood that contains genes for an immunity to anthracnose.
The origin species was largely wiped out by this deadly disease. Disease resistance is an important reason that growers continue to develop cultivars.
There are a dozen plant hardiness growing zones in North America with very different climates. The zones are defined primarily by their seasonal temperature range (highs and lows) and overall length of growing season.
Different varieties of plant life thrive in the cooler New England growing zones than in the warm, humid Southeastern region. Here in Northern Virginia and Maryland, we are in the Mid-Atlantic region. We sit in between the cooler and warmer zones to the north and south. Our garden designs benefit from cultivars of both Northern and Southern origin that adapt well to our climate conditions.
We use cultivars of northern-origin plants bred to tolerate our Mid-Atlantic heat and humidity. We use cultivars of southern origin plants bred to tolerate our winter cold. The breeding of cultivars extends the range of the origin plants making them more versatile and able to do well in our region.
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What Are “Native” Plants?
What does the term “native plant” mean? It refers generally to those plants and trees that existed before Europeans settled in North America. Specifically, within North America, there are plants that are native to particular regions or growing zones. These are the plants and trees that naturally populate our wild forests, fields, and wetland environments.
In landscaping and garden design, when we refer to “natives”, we usually mean plants that are native to our Mid-Atlantic region. We also use plants in landscaping that are sourced from outside North America. These are called “exotics” or “non-natives”. We use cultivars of both native and exotic plants in garden design.
Natives vs. Cultivars vs. Exotics
One of the first distinctions to understand about native plants is the difference between straight natives and cultivars (sometimes called “nativars”). Some cultivars are a seedless variety of native plants. This is not ideal from a biodiversity standpoint, because with a seedless plant you’ve eliminated a food source for wildlife.
We also use cultivars of exotic plants in our garden design plans. “Exotics” are plants that have been introduced to North America because they adapt well to particular growing zones. Many of our favorites come from Asia.
If a cultivar supports wildlife and gives you the look and other characteristics you want in your yard, that is a good option. When developing a planting plan, native cultivars are favored over cultivars of exotic species because they continue the characteristics of the parent plant that contribute to a vibrant healthy environment and support wildlife diversity.
For example: Native trees such as white oak, river birch, and cypress host a wide variety of insects. Songbirds and other animals feed on the bugs in a biodiverse habitat. Non-natives like Japanese maple or Chinese cherry trees don’t offer these bountiful food sources.
We wouldn’t think of excluding exotics because they make a tremendous contribution to the beauty and variety of a landscape. We simply try to balance the number of “guests” in our landscapes with those that naturally provide food and shelter for pollinators and otherwise contribute to a healthy ecosystem.
Popular Cultivars By Category
Trees
Cultivars of native spring flowering trees such as dogwood, redbud, and cherry are always popular.
Growers will sometimes create a “weeping” form of a flowering tree by cutting a lateral branch and grafting it to the trunk of another tree. These branches are “programmed” to grow horizontally so they tend to bend over rather than go up straight. There are cultivars of birch, cherry, and redbud that are bred to take this form.
Shrubs
Azaleas are cultivated to display a variety of flower colors. Euonymus, an evergreen shrub also known as “burning bush” for its crimson autumn color, is cultivated to have variegations in the foliage. Fruiting shrubs like blueberry, serviceberry, and holly are cultivated to fruit more heavily and with vibrant color.
Flowering plants
Almost every native perennial has cultivars to broaden the color palette, growth habit (size), or to extend bloom time. Creeping phlox, dianthus, yarrow, echinacea, and many others have all been bred for extended color range. Hosta has been bred to display variegations of leaf color.
Ground covers
We use a lot of liriope in our garden designs. Although a naturalized plant, introduced to the US years ago, liriope doesn’t have a negative impact on the ecosystem. It has over the years been bred to show variegated varieties.
There are many types of sedges used in garden design. Low growing carex, for example, can be put to use as ground cover, and taller versions can be used as an ornamental grass. Carex is shade tolerant and doesn’t mind wet areas unlike most ornamental grasses.
Ornamental Grasses
The ornamental grasses are prairie grasses by origin. They are tall and can’t be mowed like a lawn. Miscanthus “morning light’ has a variegation that gives a silver tone to the grass blades when viewed from a distance. Miscanthus, by the way, is a non-native (exotic) plant that in its original form can be invasive. The cultivar was developed to suppress that unwanted quality and retain the beauty.
Some cultivars are created to modify height (miscanthus can get to 8 ft). Other grasses are bred to show off different colors in the flowering seed heads, and others for stronger stems that are more sturdy against wind or strong rains.
Turf grasses
These are cultivated for specific purposes. There are shade grasses and full sun grasses. Tall fescue is used for sunny lawns. Red fescue and fine fescues prefer shade. We also have shade mix fescues that do well in filtered light.
Buffalo grass is a native grass that can tolerate drought conditions because the roots extend two feet deep. Fescue grasses reach 4-6 inches and are kept at 3.5 to 4 inches height. Buffalo grass must be maintained at 5 inches minimum. So, as a lawn grass it would not be for everyone.
Why We Use Cultivars in Garden Design
Cultivars are constantly being developed by growers and college extensions to take hardiness traits from a related plant and put them into the desired landscape plant. They may breed them for cold tolerance, heat tolerance, or resistance to new and emerging diseases or pests. They can also be bred to bloom later in the spring to avoid a late frost or to have extended blooming periods.
Although we have no control over how Mother Nature will treat our landscapes over the seasons, we have learned over time to be adaptive and proactive in the areas of garden design, plant selection, and garden care practices.
With good planning and regular landscape maintenance, we are able to maximize the beauty and longevity of the types of outdoor environments our customers ask us to create for them.
If you’d like to learn more about what goes into designing a vibrant and successful landscape, download our ebook “The Expert Guide to Planning the Landscape Design of Your Dreams”.
If you’d like to discuss improvements to your current landscaping and garden design, feel free to schedule a consultation with one of our Garden Managers.