Cultivars Enhance Landscape Plants
Written By: Bruce Spangenberg, Horticulture Outreach Specialist
Winter is a suitable time to look ahead to the 2025 growing season and research potential plants to add to your landscape. Knowing how plants are correctly named, and the importance of cultivars are key components in finding that perfect plant to fit different landscape situations.
While researching plants you may run across assorted terms used to identify plants, including genus, species, common name, cultivar, and variety. Every plant has a unique scientific or botanical name, which are italicized and always in the format of genus (capitalized) followed by specific epithet, or species (lower case). For example, Acer rubrum has the botanical name red maple. Common names are typically used in conversation, but are sometimes regional, and there are entirely different plants with the same common name.
Cultivars and varieties become key factors when selecting many types of landscape plants. Both terms refer to variations in traits within species including flower color, plant size, form, hardiness, and pest or disease resistance. Technically varieties are naturally occurring variations whereas cultivars have been developed through crop breeding.
Knowing complete names of landscape plants and how cultivars may alter appearances of species ensures correct plant identity. For example, Norway maple, Acer platanoides, is a widely planted large tree with green foliage turning brilliant yellow in fall. Cultivars such as ‘Crimson King’, however, provide maroon color throughout the growing season, and are oftentimes incorrectly called red maples.
Red maples are green in summer and many turn red in fall but are sensitive to high pH (alkaline) soil. As a result, they often suffer from chlorosis (yellowing foliage) in many landscapes. This is an entirely different tree than Norway maple, thus the importance of using the correct full names of trees.
Flowering crabapples (Malus species) are popular landscape plants featuring assorted combinations of flower and fruit colors, sizes, and overall tree form and size. Most of these ornamental characteristic combinations are due to the genetic makeup of numerous cultivars and varieties. Likewise, cultivars and varieties of flowering crabapples can also be extremely effective ways to reduce disease problems these trees face, including apple scab, cedar rust, and fireblight.
If you have an apple scab susceptible crabapple, in seasons like 2024 this fungal disease will often defoliate the tree by midsummer. The only defense is to properly apply appropriate fungicides starting before the disease developed each spring. However, scab resistant cultivars have genetic resistance, thus see much less if any impact from scab.
Always know the full name of any plant you are considering adding to your landscape and recognize the importance of cultivars (and varieties) in selecting landscape plants in 2025!
Bruce Spangenberg is a Horticulture Outreach Specialist with UW-Madison Division of Extension. Get answers to your lawn, landscape, and garden questions anytime at www.go.wisc.edu/GardenQuestions
