With the surging interest in pollinator gardens and habitats, it is great to see so many home gardeners, parks and public spaces embrace the concept. When I first started looking into pollinator gardens, I thought any plant that attracts pollinators would do in all cases. Of course, any plant that supports animals whose habitats are shrinking is a move in the right direction. However, not all plants are created equal when it comes to supporting pollinators in the garden.
Pollen and nectar are actually two different things. A basic understanding of their function and role in our gardens can help support the creatures that visit your garden.
Pollen grains are microscopic. They are the male component in the sexual reproduction of flowering plants. Although some plants, such as grapevines, are self-pollinating, cross-pollination ensures genetic diversity and the ability of plants to adapt to changing conditions. When pollen lands on the female part of a flower, this sets the stage for fertilization and reproduction.
Some pollen grains are very light and can be dispersed by wind. Heavier grains may be sticky and rich in protein to attract pollinators. While we typically associate bees with pollen transfer, many other insects and arthropods may eat or transfer pollen between flowers. Ants, some flies and even beetles are just a few examples.
Even some spiders consume pollen when it is attached to their prey. In fact, the orb-weaver spider consumes pollen when it eats its own web. Since pollen plays such a crucial role in the animal and plant world, plants have devised many ways to move this precious genetic resource around.
Nectar, by contrast, is a sugary liquid produced in plant glands called nectaries. Nectar attracts animals that inadvertently pick up pollen grains and transfer them to other plants. Pollinators brush the reproductive structures inside the plant when attempting to access the nectar.
Although primarily used as a lure, nectar is also converted by bees into honey. Carnivorous plants use nectar to attract prey. Nectar also attracts “bodyguards” that protect the rich nectar source. Ants protecting their passion flower host from caterpillars is a classic example. Other well-known plants that have such relationships include beans, peas and some other legumes.
Both pollen and nectar play an important part in feeding or attracting a vast number of species to our gardens. If you are interested in establishing a pollinator garden or incorporating one into an existing project, select plants according to what they contribute. Also consider the types of critters you want to visit your garden. To attract butterflies, incorporate nectar-producing plants that will attract and support butterfly species in your area. To encourage native bees, bumblebees and other primary pollinators, look to the many non-invasive plant selections available. Plants that attract predatory wasps can help control other insect pests and caterpillars.
Consider heirloom cultivars that have not been manipulated for color at the expense of robust nectar production. Be sure to include native plants and those with overlapping flowering times, particularly during winter. Some night-blooming flowers can provide additional sources of nectar for the night crew.
Group plants by type to help pollinators locate them easily and gather what they need. Of course, reducing or eliminating pesticides is always a great strategy in helping your garden to thrive.
Most garden shops and seed catalogs have a staggering variety of plants and flowers that will attract pollinators. Also consult the University of California website, accessible via the Master Gardener website (address below), for more information.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.