Pathway Guidelines for Pollinator-Friendly Gardening
The Pollinator Pathway encourages native plantings in our landscapes to promote biodiversity and ecosystem health.
Pollinator-friendly yards should strive for 70% native plants. This includes trees already present such as oaks, maples, cherries, native shrubs, perennial plants, grasses, ferns and ground covers. Whenever possible, straight-species/wild-type natives should be planted since they grow naturally in your eco-region (A.K.A. ecotypes).
Caution should be taken for planting native cultivars as they may not offer the same benefits to pollinators, birds and other wildlife as the straight species provide. For example, when nurseries propagate plants by cuttings, they have the same genetic makeup as the parent plant, creating a lack of genetic diversity critical to ecological systems.
It is important to note that more research is needed to answer questions regarding benefits of native cultivars vs. straight-species native plants. Cultivars need to be judged on an individual basis for their value to pollinators. Studies done by Annie White, University of VT, suggest that some native cultivars attract pollinators as well as the straight-species. However, no research has been done to determine nutritional value of pollen that native cultivars produce. We do know that pollen is most crucial for developing bees, especially specialist bees that require pollen from a specific plant or plant species.
Based on current research, native cultivars that should be avoided because they have no wildlife value are:
• Plants with dark colored leaves that contain anthocyanins.
• Flower color that is different than wild-type.
• Double flowers pollinators cannot access.
• Flowers that are sterile.
• Shrubs and trees with changed size and shape because they are unattractive to nesting birds.
Studies on Native Cultivars
Annie White: Are Native Cultivars as Valuable to Pollinators as Native Species?
Mt. Cuba Center: Do Leaf Eating Insects Eat Native Cultivars?
Penn State Extension: Bees, Bugs and Bloom
These are introduced and ornamental plants, trees and shrubs are generally grown for aesthetic reasons for gardens and landscapes. They have little or no value to pollinators and other wildlife. While many non-native plants are benign for aggressive spread, many of these trees and shrubs dominate our landscapes. As development increasingly encroaches on our wild places, our native flora is replaced by exotic plants and lawns. Doug Tallamy, Professor, Univ. of DE, states “We are replacing native plants with introduced species at an alarming rate, especially in the suburban garden on which our wildlife increasingly depends.”
Care should be taken, not to purchase plants that have invasive potential such as Japanese Barberry, Euonymus Burning Bush, Norway Maple or Bradford Pear. Any plant listed on your state’s Invasive Plant List should be avoided, even if not banned from sale.
These plants complete their life cycle in one season and are not a threat to biodiversity. Many of these plants can attract pollinators and beneficial insects to supplement your garden. Many herbs are attractive to pollinators. For example, parsley, dill and fennel are host plants for the Black Swallowtail butterfly caterpillar. They are closely related to our native Zizia aurea, Golden Alexander. However, caution should be taken to ensure that plants have not been treated by a nursery with neonicotinoids that are deadly to pollinators.