Speaking of interplanting to achieve diversity in the vegetable garden ecosystem, what about mixing in a few annuals that attract native pollinators? The idea is appealing: a vision of orange calendula blooms poking through the dark green leaves of winter squash, bees and beetles swarming over the blossoms of both. But would it really work that way? Would the same pollinators that visit the calendula also service the squash? Would another species of annual flowering plant be a better choice?

These are not well-researched questions and many authorities suggest that gardeners concentrate on perennials for attracting native pollinators. There are a few annuals, however, that are known to attract pollinators, particularly the native bees.

In general, native bees prefer annual flowers in shades of purple, blue and yellow. The lilac flowers of verbena (Verbena bonariensis), for example, attract not only native bees but also butterflies, while the deep violet-blue blooms of heliotrope (Heliotropium arborescens), with their strong vanilla fragrance, are always covered with bees in search of nectar.

Some bee-attracting annuals also provide leaves and-or flowers for human consumption and thus are excellent candidates for integration in the vegetable garden. As the purple flowers of anise hyssop (Agastache foeniculum), an annual herb or tender perennial in Maine, provide nectar for bees from June to August, the gardener can harvest the aromatic leaves for their sweet, licorice-mint flavor. Fresh or dried, they add flavor to salads, teas and garnishes. And the hundreds of small blue flowers of borage (Borago officinalis), a tall annual herb (18-30 inches high), do double duty, providing both nectar and pollen to foraging bees while adding a mild cucumber flavor to salads and garnishes.

I was pleased to find nasturtiums (Tropaeolum majus) recommended for attracting native bees to the garden. Marjorie and I always grow pots of climbing nasturtiums on the porch, allowing their trailing stems to cascade over the railing. This year we will also place pots of nasturtiums among the vegetables, a moveable feast for the bees. Nasturtiums’ blooms are edible, as well, adding color to summer salads.

Calendulas (Calendula officinalis) do make the cut, but only the single varieties. The gardener interested in attracting pollinators should avoid all annuals with double flowers (varieties in which the pollen-bearing stamens have been replaced with petals), since the pollen production will be greatly reduced or eliminated entirely. As calendulas are self-sowing annuals, coming back from seed each year, their location in the garden is managed by weeding out the unwanted seedlings. This means a little more work, another reason to linger late in the garden at the end of the day, and it makes for delightful plant combinations that you would have never thought of yourself!

Finally, there is comfort in realizing that the yellow flowers of broccoli and other brassicas will bring native bees to the garden. This is great solace for those of us who experience bolting of these crops every spring. We can leave them be, along with a few radishes left in the ground to flower.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.