by Terry Twigg
(August 1, 2022) — High summer, and we’re in a drought. Leaves are wilted, the grass crunches underfoot, and my poor pond, which is actually a dammed-up stream, has shrunk to a mud puddle. Its overflow pipe, useless, sticks up a foot and a half above the water level. The flower beds have a look of stoic endurance in the glare, and even the frogs in Raphael’s pool hide themselves away in the shade of overhanging rocks.
But, wait until dark. On all but the very hottest days, evening brings cooler air, and the gardens almost stand straighter. I find myself wishing for a project I’ve long dreamed of but not yet gotten around to: a moon garden. If you’re not familiar with the term, a moon garden is essentially a white garden. All your favorite white annuals and perennials shine at night, but the moon garden is also planned to include as many as possible of flowers that open in the evening, such as moonflowers, four o’clocks, evening primrose, and angel’s trumpet, all of which also offer heady fragrance. Most daylilies open in the morning and close by dark, but there are plenty of nocturnal varieties, which reverse the timing, and some of these are also fragrant.
Pure white isn’t essential. Soft pastels stand out almost as well in twilight, and greyish or variegated foliage contributes ghostly shapes: fuzzy lamb’s ears; variegated hostas and euonymous; misty artemisia. There are even a few flowers that actually fluoresce at night, including four o’clocks and portulaca.
To this mix, add more flowers that fill the darkness with perfume: night-scented phlox, evening-scented stock, nicotiana, petunias, and of course, roses and lilies. If your moon garden is in an enclosed area, the scents will be contained and enhanced.
If you think you can’t build a moon garden with native plants, think again. For height, plant native dogwood trees, mountain laurel, and the white American wisteria “Nivea.” For mid-level interest, choose clethra and native viburnum. Then fill the beds with white coneflower, spotted horsemint, Culver’s root, asters, and white Joe Pye weed. Whether native or imported, try to plant several of each variety together. You want big, showy groupings that will be visible from a distance, not singletons dotted around the yard.
Of course, all the features that lure you out into the evening don’t just happen by chance. Big white flowers, easy to see in the darkness, or strong perfumes that carry on night breezes—as glamorous as they seem to us, the simple truth is that they’re strategies to lure night-flying pollinators. Most bees and butterflies are diurnal, meaning they fly during the day and rest at night. Darkness is the domain of nocturnal pollinators, most notably moths and my beloved fireflies. Also, to my surprise, bats, though not so much in our part of the country.
I see all three emerging at dusk. The most noticeable and identifiable moth is the sphinx moth. Some can hover like hummingbirds, earning them the nickname “hummingbird moth,” and may be mistaken for hummingbirds, especially when the light is fading. Also like hummingbirds, they are equipped to reach into long tubular flowers. While the birds have long narrow beaks, the moths have a very long proboscis, or tongue. Charles Darwin, looking at a tropical orchid with a throat over a foot long, famously predicted that there must be a moth with a proboscis equally long in order to reach the pollen and nectar at the base. Colleagues laughed at him, but he was vindicated years later, when just such a moth was discovered.
The bats’ movements are erratic but fun to watch as they swoop back and forth, with constant redirection mid-flight. I find them charming in the air, more so than when I found one panicking in my bedroom a few months ago. But suddenly I was slammed by conflicting loyalties. Like so many other creatures, bats are threatened by disease, so I rejoice to see these ones healthy and active. But are they flourishing at the expense of the moths? The fireflies?
Enter science. I (and until recently, most scientists) thought firefly displays were only for courtship. Turns out, they’re also warning signals. Some firefly species are toxic to bats. Others are naturally non-toxic, but cannibalistically eat their smaller cousins in order to acquire the poison. The lights are a signal to hungry bats to back off. Moths take the art of self-defense several steps further. As with the fireflies, some moths are toxic, some merely taste bad, and some are perfectly bat-edible. The nastier ones defend themselves with ultrasonic signals, and the more edible species have evolved to mimic the sounds. Researchers are still unsure whether the sounds are merely warnings, or if the moths are actually jamming bat frequencies! Suddenly the bats’ jerky flight path makes sense: maybe they’re homing in on prey, only to veer off at the last second when enemy shields are deployed.
My dreamy white garden, shimmering in summer moonlight, is actually a high-tech battle zone. I’m still going to make one someday, though. Next full moon: August 11th.
