Since you are reading my blog on green roofs, I assume that you basically know what they are, and may know of one in your area. You may also know about pollinators-those wonderful insects (bees, moths, butterflies, etc.) that are essential for production of seeds and fruits of native plants and crops. You may even be aware that pollinators are in trouble. And if the pollinator populations are in trouble, our food crops are too…. We may have to start hand pollinating our veggies and cereal plants!
Let me briefly discuss what’s happening AND what we can do to help.
As cities and suburbs sprawl, there is less native land available for these pollinators. Turf grass really holds no ecological value for the pollinators- they are looking for flowers with nectar and pollen. Further, impervious surfaces (rooftops, parking lots, streets) are not inhabitable for the species either. In addition to the lack of natural ecosystem habitats, distance between them, and parasitic mites, pollinators have another challenge.
Research is suggesting that plants grown with specific pesticides are killing colonies- either from hives with direct contact during the spray application, or systemic (plant retains the active ingredient and the pollinators absorb as they contact the plant). Now, I’ll restrict myself from completely geeking out, but the class of insecticides is call “neonicotinoids” (think nicotine for bees) and the active ingredient is Imidacloprid. BayerAg makes this, and is common in many products you may buy over the counter at a box store: Merit (grub control), flea and heartworm control for dogs and cats, and Confidor (used on many fruit trees, commercial vegetables, and ornamentals). Commercial growers who supply large numbers of ornamentals for big box stores probably use these insecticides to manage their crops. For those “green-thumbers” out there: home gardeners, professional landscapers, Master Gardeners…Anyone who has bought a plant for in their yard or around their business, we have probably unknowingly been planting harmful plants! Yikes.
Armed with knowledge you can work to change this in your personal and professional life. Just start asking the questions at the garden center “Where do my plants come from? How were they grown?” Consider going elsewhere if you aren’t comfortable with their answer. As a general rule, grower of natives and certified organic growers of crops are likely in the clear. Of course, if you start your own seeds, you have ultimate management control :) Once you find a garden center that you trust, select plants like Coreopsis, purple coneflower (Echinacea), rough blazing star (Liatris), and milkweed (Asclepias). These are also good green roof plants when designed properly!
I am excited about an upcoming green roof that will be planted soon. We are using natives and wildflowers to cover a building intended to blend into the existing landscape. There are some shallow areas where we’ll be growing succulents, too, so this one-acre roof will jam packed with safe food for our pollinators!
Are you interested in selecting healthy plants for pollinators on a green roof? Contact AD Greenroof or start here: http://beelab.umn.edu/About/Pollination/index.htm