Researcher compiles list of flowers most beneficial to bees
July 08. 2018 10:12PM
DURHAM — New Hampshire Agricultural Experiment Station scientists have developed a list of the most beneficial wildflowers to plant to support the state’s native wild bees.
“The interest in helping pollinators has been astounding. There are literally hundreds of pollinator gardens and habitats that have been installed in New Hampshire alone in the last few years,” experiment station researcher Cathy Neal said.
Neal has conducted nearly 10 years of wildflower meadow trials at the experiment station’s Woodman Horticultural Research Farm.
She has found that wildflower meadows comprising herbaceous perennials such as golden rod, asters, black-eyed Susans, bergamot, coneflowers and potentially many more are extremely valuable places for bees to forage for food. The New Hampshire wildflower mix is ideal for medium to dry soils in full sun.
Neal has also evaluated different seeding rates, to find the optimal balance between wildflower density and cost, since wildflower seed is expensive.
“The more species of wildflowers we can pack in, the better, with the goal being to have something in bloom for the bees from May through late October,” said Neal, who also is a horticulture specialist with University of New Hampshire Cooperative Extension.
Pollinators are essential for most of the fruit and vegetable crops produced in New England.
According to a UNH news release, the value of pollination to agriculture is estimated at more than $200 billion a year worldwide. However, the abundance of and diversity of pollinators are declining in many agricultural landscapes across the United States.
New Hampshire has a rich diversity of native bees that provide pollination services, often more efficiently than managed colonies of honey bees, the news release states. However, habitat loss associated with development is one of the leading threats to pollinators. Neal’s research focuses on how to best provide safe habitat and a healthy food supply for native bees in gardens, fields, and neighborhoods.
According to Neal, the first step to starting a meadow from seed is to eliminate existing vegetation since non-native, spreading grasses are the biggest challenge to wildflower establishment.
This can be done several ways: use of a non-selective herbicide, which is most effective; covering with black plastic for the whole summer; covering with clear plastic; or repeated tilling.
Covering with black plastic in the summer following by fall seeding was proven to be nearly as effective as herbicide use.
“Even with the best practices, establishing a wildflower intensive meadow is a three-year process. With the first year spent on site preparation, the second season will produce green seedlings but few flowers. Weeds such as crabgrass are apt to dominate so a mid-summer mowing is often essential.
“The third year is when you — and the bees — finally see the results of your efforts, with a sequence of colorful blooms emerging from tall, robust plants. Once established, a dense, diverse meadow requires virtually no inputs such as irrigation, fertilization or pest control,” Neal said.
Neal’s meadow plots at the Woodman Horticultural Research Farm now range from one to nine years old.
With the help of student assistants, she continues to inventory and evaluate them several times each year, keeping records on how the species and weed competitors change over time.
More recently, Neal has been evaluating the relative attractiveness of new varieties of old standards such as purple coneflower, Echinacea purpurea, a common garden perennial. It appears that the breeding process, which has resulted in hundreds of novel forms and colors of coneflowers, has inadvertently reduced the incentives for bees to visit them.
All types of bees, Neal said, liked the old standard Magnus as much or more than the regular, seed-propagated Echinacea purpurea.
“Watching the evolution of the meadow and monitoring bee species to determine the best ‘bang for the buck’ when investing in a wildflower meadow, continues to bring surprises and generate new ideas,” she said.
Neal has presented this research at the American Society for Horticultural Science Annual Conference and the National Protecting Pollinators in Urban Landscapes Conference. This material is based upon work supported by the NH Agricultural Experiment Station, through joint funding of the National Institute of Food and Agriculture, U.S. Department of Agriculture and the state of New Hampshire.
For more information on establishing a wildflower meadow, visit https://extension.unh.edu/tags/wildflower-meadows.