In Madison, July is the warmest (on average) and the second wettest (on average) month of the year. Extreme heat and significant drought can also occur mid-summer. As July begins, the Madison area is in severe drought, and we have had multiple days with above average temperatures. The low rainfall pattern began in early to mid-May, crossing into drought in June. The native plant garden is largely resilient to these environmental conditions, although we do see effects like shorter plants, accelerated bloom phenology (timing) in some species, fewer flowers produced, seeds not developed fully, and shorter blooming periods. Garden tasks are weeding, trimming, monitoring bumble bees, planting when conditions permit, and spot watering new plantings when drought persists. Fortunately, our new plantings this year are mostly in cooler shaded areas.
With many prairie and savanna plants coming into bloom in July, diverse groups of pollinators, especially bees, forage on and pollinate this wide diversity of flowers. For plants, the result of pollination is fruit and seed production. For bees, pollinating flowers is a side effect as they search for and gather resources for themselves and their young. They collect pollen as food for larval bees. Adult bees feed on nectar as an energy source. However, that is an oversimplified description, as nectar and microbes occurring in flowers are combined with pollen and the mixture becomes a nutritious larval food.
We are currently seeing eight bumble bee species foraging on native plant species: leadplant (Amorpha canescens), wild white indigo (Baptisia alba), purple and white prairie clover (Dalea purpurea and D. candida), New Jersey tea (Ceanothus americana), pale purple coneflower (Echinacea pallida), native roses (Rosa spp.), smooth penstemon (Penstemon digitalis), milkweeds (Asclepias spp.), and more. Later in the month, the bees will switch to new blooms like bee balm (Monarda fistulosa), blazing stars (Liatris spp.), culver’s root (Veronicastrum virginicum) and many more.
In the horticultural collection, they are visiting St. John’s wort (Hypericum spp.), flowering raspberry (Rubus odoratus), roses (Rosa spp.), several Spirea species, Dutch white clover (Trifolium repens), and more.
Many people are learning about bumble bees through the Arboretum this summer. In just the last 10 days, a field ecology class learned identification and completed a study of bumble bees foraging on wild white indigo. Their surveys are submitted to Bumble Bee Brigade. A lab group studying pollinators in agricultural sites learned how to survey monarch life stages and bumblebees. On two local field trips we introduced over 60 people to bumble bee identification, life history, and plant resources. A radio station reporter visited the native plant garden to learn about ways to promote pollinator conservation, especially on farms. We replied to two inquiries about bumble bee nests, one discovered during a home remodeling project and the other at a research site.
If you are interested in learning about bumble bee identification, life history, monitoring, and conservation, consider attending one of our upcoming sessions on Sunday, July 9, or Sunday, August 13, from 9 a.m. to 12 p.m., at the Arboretum. These workshops will include a presentation and time outdoors in the garden observing and photographing bumble bees. We will introduce the Bumble Bee Brigade project and provide additional resources. Please register by emailing Susan Carpenter and indicate which day you would like to attend; each workshop is limited to 20 participants.
Looking ahead to late summer, native bees is the topic of our keynote talk by Heather Holm at the Arboretum Native Gardening Conference on September 10. Registration for the conference, which will include workshops on garden design, management, invasive species, native plant identificaiton, native trees and shrubs, pruning guidelines, and nature journaling, plus garden tours, is open now.
Deepen your understanding and appreciation of summer flowers and pollinators this season.
—Susan Carpenter, native plant garden curator