National Pollinator Week

By Peg Ricco,  PegPlant.com

 This week, Celebrate National Pollinator Week 

It's the perfect time to learn more about pollinators, identifying the best plants and trees for pollinators in your area, and incorporating best practices to protect, harbor, and feed pollinators. 

It is amazing that something as small as a bee is vitally important to our food supply. As pollinators, bees transfer pollen thus ensuring that plants and crops develop fruit and seeds for us to consume. But bees are not the only keystone species that we depend on, we also need other pollinators such as butterflies, moths, beetles, flies, and birds, including hummingbirds. 

About 80 percent of the world’s flowering plants depend on pollinators (the others are wind pollinated). According to Cornell University, pollinators are responsible for every third bite of food we eat. Unfortunately, pollinator populations have declined due to pesticides, habitat loss, and disease. Gardeners who are aware of this problem have deliberately planted flowering perennials and annuals to provide pollen (protein) and nectar (carbs). Because of their dramatic 90 percent decline in population over the past 20 years, monarch butterflies have received quite a lot of support. Many gardeners are planting milkweed – the one and only plant for monarchs — or trying to produce more butterflies with home kits. Bees too have received national attention. Nurseries promote bee friendly flowers and gardeners have planted bee magnets such as Joe-pye weed (Eupatorium), goldenrod (Solidago), and gayfeather (Liatris).

 

Persimmon fruit, thanks to pollinators

These efforts have helped the pollinators and certainly gardeners have come to appreciate the importance of pollinators. However, an overlooked source of food and protection for pollinators are trees. Trees provide more flowers, plenty of foliage for larva (caterpillars), and a large infrastructure to hold hives and nests. Because of the number of flowers a canopy provides, trees can provide more pollen and nectar compared to annuals and perennials. Plus, as homeowners move from house to house, the herbaceous landscape may change but usually the trees and all of their tiny inhabitants remain.

Plant Small Native Trees for Homes                                                                                            “Trees are a permanent fixture,” said Steve Nagy, an International Society of Arboriculture (ISA) Board-Certified Master Arborist and Assistant District Manager at the northern Virginia office of the Davey Tree Expert Company. Based in Ohio, the company was founded in 1880 and has offices across North America.  For attracting pollinators in the Washington DC metro area, Steve recommends native trees that thrive in our particular climate (cold winters and hot, humid summers). “We recommend native trees because the chances of them growing well is higher that non-natives,” he explained. For typical suburban lots where space is a premium, Steve recommends swamp white oak (Quercis bicolor), willow oak (Quercis phellos), post oak (Quercis stellata), cucumber magnolia (Magnolia acuminata), sweet bay magnolia (Magnolia virginiana), black gum (Nyssa sylvatica), little leaf linden (Tilia cordata), persimmon (Diospyros virginiana), and serviceberry (Amelanchier). “Sourwood (Oxydendrum arboreum) is a great tree, too,” said Steve, “It is a typically overlooked native with good fall color.”

The crape myrtle branches bend down

Plant Trees that Flower at Various Times with summer-blooming flowers. While a tree can provide many flowers, usually it only flowers for a few weeks. Because different pollinators are active at various times of the year, Steve recommends planting trees with various bloom times. Instead of planting the well-known spring bloomers such as flowering cherry trees, flowering plums, star magnolias, saucer magnolias, and redbuds, homeowners can plant summer blooming trees such as little leaf linden, persimmon, cucumber magnolia, southern magnolia (Magnolia grandiflora), and crape myrtle (Lagerstroemia).                                                                                                 

Plant Trees that Support Specific Pollinators. 

Another reason to plant trees is that certain pollinators require specific tree species or genera. Similar to the monarch butterfly’s relationship with milkweed, the spicebush swallowtail caterpillar only feeds on spicebush (Lindera benzoin) and sassafras (Sassafras albidum). The zebra swallowtail caterpillar only feeds on young paw paw leaves (Asimina spp.) and the pink-striped oak worm moth gets its name from its preference for oaks (Quercus spp.).

Paw paw trees are vital to the zebra swallowtail butterfly