Garden Notes

trumpet vine
This colorful trumpet vine is perfect for the hungry hummingbird. Photo by Susan Safford

Hornets, hummingbirds, and honing vegetable gardens

By Abigail Higgins - August 30, 2007

Of interest to gardeners and nature lovers, from the United States Postal Service web site: The Post Office has released the four-design, 20-stamp Pollination booklet. The design "...emphasizes the ecological relationship between pollinators and plants and also hints at the biodiversity necessary to ensure the future viability of that relationship. The four designs are arranged in two alternate blocks that fit together like interlocking puzzles. In one block, the pollinators form a central starburst. In the other, the flowers are arranged in the center."

The subjects: bumblebees with nightshade, hummingbird with trumpet vine, bat and cactus flower, and a butterfly visiting ironweed. The series is beautiful and serves not only to decorate our mundane postal transactions but also to remind us of the crucial importance of the zillions of mundane pollinating transactions that insects and animals provide for us.

Attracting hummingbirds

On the subject of hummingbird pollinators, for many the lead-in is being captivated by the pastime of watching them. Our one New England resident species is the ruby-throated, Archilochus colubris. I enjoy placing plants in gardens that attract them, especially if children are in residence. Brightly colored, non-fragrant, nectar-bearing, tubular shaped blossoms are what the tiny creatures look for. The fuchsias (note the spelling: named for Fuchs, the botanist), especially the upright fulgens cultivars, four o'clocks (Mirabilis jalapa), and trumpet vines (Campsis and Bignonia spp.) are all reliable magnets. Once the hummingbirds visit a garden and find food, they and succeeding generations reliably return.

A surefire container combination for attracting hummingbirds, if you like deep dramatic colors, is a grouping of upright Fuchsia 'Gartenmeister Bonstedt,' cascading orange Russellia equisetiformis, centered with a burgundy cordyline spike. Place the container in full sun, preferably where you can see it from inside; the hummingbirds visit regularly.

Even more fun is to augment the hummingbird's flower and insect dinners with hummingbird feeders. As many people know, these dispense sugar syrup made by boiling four parts water and one part sugar together. Since the early days of feeders, a number of improvements have been made. Look for ant moats, perches, and easy-to-fill and-clean designs. Refill and clean the feeders regularly to prevent mold from forming.

I separate feeders by placing them on opposite sides of the house; hummingbirds, despite their small size, are feisty, territorial birds. Driving off other hummingbirds is standard behavior. This separation seems to allow more birds to feed: every seven to ten minutes, another bird arrives. The porch feeder is suspended from a plant hanger where I can observe it from this desk. I have just seen a funny reverse drama: a female hummingbird zoomed in from one side when a white-faced hornet zoomed in from the other and drove her off! (She was back in a minute, though, minus the hornet.)

Hornets and horticulture

The above-mentioned white-faced hornets, also called bald-faced hornets (Dolichovespula maculata), are very visible now - both the creatures themselves and their large papery nests - causing anxiety among gardeners, caretakers, and others who have reason to be in proximity to one of the basketball-sized objects. At this time of the season the nests are approaching their maximum size; falling leaves and growing size may cause one of them to suddenly appear, as if "out of nowhere," and make one feel as if one must do something.... This is a plea from me to exercise restraint, should you discover that you are hosting a nest of these beautiful members of the Hymenoptera.

Generally the hornets - really large yellow jackets, according to "Garden Insects of North America" by Whitney Cranshaw (Princeton University Press, 2004) - build their nests in innocuous spots: high in trees, under an over-hanging eave, in woodsheds, or in dense shrubbery. Unless human and insect paths cross negatively it is unnecessary to "do something.'' In fact, the wasps are beneficial insects and are actually good to have around.

Bald-faced hornets, according to Cranshaw, "...produce large aerial nests covered with a papery shell. These nests are produced annually, started by a single fertilized female in late spring and then abandoned at the end of the season. [They] rear their young strictly on a diet of living insects, particularly caterpillars. Although they sting if the nest is disturbed, these insects are largely beneficial to gardeners because of their importance as biological control agents of pests."

In my experience, white-faced hornets can become testy in wet weather, but otherwise I find them good neighbors. I have read anecdotes of white-faced hornets systematically catching flies around livestock operations and preying on smaller yellow jackets, both of which they feed to their young. They are commonly seen on shingled surfaces or split-rail fences, scraping the wood with their mouthparts for papermaking.

Vegetable gardens

The windy spell last week toppled kale plants in my garden; hilling them up with soil seems to be doing the trick to stabilize them. Continue with Bacillus thuringiensis (Bt) on all cole crops, on a weekly basis, to protect them from cabbage caterpillars. As crops are harvested, opening up empty space in the garden, consider planting a cover crop.

Buckwheat, a warm weather plant, is a quick coverer and grower that frost will cut down for you if you do not get around to tilling it in first. It reportedly supplies additional silicon to soils. The beneficial effects of increased silicon, according to on-going studies by the Agricultural Research Service and others, appear to be suppression of disease but also include improved photosynthesis leading to increased growth in some plants, decreased susceptibility to fungal pathogens and insects, and amelioration of environmental stresses.

Late planting of cool weather crops is still possible too, principally all sorts of greens. Enrich row space and leave open for shallots and garlic. The seed becomes available in September and October, which is the recommended planting time here on the Island. Continue to clean up and compost garden debris as it accumulates. Deadhead sunflowers, but try sticking their seed-heads somewhere where goldfinches can still harvest the seed. I poke them high up into the deer netting enclosing my vegetable compound. They are rapidly picked clean.