Moths moon over twilight in Northwest gardens

What happens in your garden when the sun goes down? Only the palest foliage can be seen in the moon’s silvery light. A moth flits past on silent wings and alights on a white blossom that seems to glow in the shadows.

This is the magical realm of the moon garden, also called a night garden or a starlight garden. It’s a space designed not only to please the eye during twilight hours but also to attract moths to your yard, those unsung heroes of the pollinating world.

“A lot of people don’t even know that moths are pollinators,” said Jessica Slatten, Washington State University Extension Master Gardener. “In the Pacific Northwest, moths overwinter in the larval stage and then emerge into adult moths when the weather warms. When they’re emerging, you want to make sure that those host plants are present.”

Slatten has been thinking quite a bit about how to make local gardens more hospitable to moths because she’s just finished developing a free, interactive Zoom workshop, “Moonlight Moth Garden,” scheduled to debut during National Moth Week, July 17-25. (For more details, visit extension.wsu.edu/clark/master-gardeners.) In the meantime, here are a few tips to get started.

Color and fragrance are key where moths are concerned, Slatten said. Pale shades reflect light more efficiently, making blooms easier for moths to see in the dark. Moths also prefer strongly fragranced flowers like tuberose, gardenia and jasmine — and the sweet smell is nice for humans, too. Moths are fond of evening bloomers like moon flowers, evening primrose, night-blooming jessamine, foamflowers or jimsonweed.

If you can’t find those specific flowers at your local nursery, any white or pale blossom will stand out as darkness falls. Try easy-to-grow calla lilies, white hydrangeas, peonies, petunias, pansies or phlox. Slatten suggested white varieties of common flowers like cosmos, impatiens, nasturtiums, foxgloves and yarrow. Slatten also urged folks not to overlook the power of the humble dandelion.

“It’s kind of a fun fact that there are some moths that are active in the day,” Slatten said. “Lots of gardeners will tolerate dandelions just because they’re such a great source of nectar for our pollinators.”

A moon garden isn’t all about flowers, however. The reflective effect can be achieved with foliage such as dusty miller or silver ragwort, lamb’s ears or curry plants. The white parts of striped leaves, such as variegated sage or mint, will also reflect light. Some varieties of sedge grass, brunnera and hosta sport silver or white leaves.

“A lot of people think about what annuals to buy, but you want to have year-round-structure,” Slatten said. “Don’t just think of the specific flower. Think of the entire garden.”

Slatten rattled off a list of structure-giving shrubs and trees that sounded like a pleasantly alliterative poem: ash, barberry, beach, birch and blackthorn. For off-season blooms, she said, plant winter daphne, Oregon grape, witch hazel, mock orange or winter honeysuckle. The goal, she said, is to try to cater to every stage of the moth life cycle — and there are many more moths out there than you might think.

“One thing that I didn’t know going into this is that while butterflies and moths are in the same order, lepidoptera, butterflies make up 6 to 11 percent of the lepidoptera order while moths make up 89 to 90 percent of the order,” Slatten said. “There are many more species of moths than butterflies.”

Moths you might see in Clark County include the red-and-black cinnabar moth, Slatten said, as well as hawkmoths, sphinx moths, and the evocatively named hummingbird hawkmoth, a species that looks like a hummingbird. To learn more about local lepidoptera and other invertebrates, Slatted suggested the Portland-based Xerces Society, www.xerces.org.

Slatten noted that a birdbath or pond may attract wildlife but they’re not ideal for moths because the water is too deep. To make moths happy, she said, put out a flat dish, like a terra-cotta pot bottom, filled with pebbles and a shallow layer of water so that moths can settle on the water without sinking into it. These damp nooks and crannies are also prime spots for frogs, slugs, snails, worms and creepy-crawly bugs that nocturnal animals like to snack on. You might even get the occasional bat or owl flying in to check out the busy after-hours scene.

No matter what comes to visit, it’s vitally important to turn off the lights and let the moonlight cast its spell.

“Many gardeners think that because moths are attracted to light that light is a good thing, but that’s not true,” Slatten said.

She added that bug zappers are a big no-no. “They don’t really control mosquitoes, studies are showing, but they do kill moths and other insects,” she said.

Slatten said the Xerces Society recommends turning off all exterior lights at night and, further, pulling the shades in lighted rooms. If you must have outdoor lights, use motion activated types that won’t shine all night long. If you put up lanterns or string lights, turn them off when not in use. Slatten also said that warm-colored LED lights are less attractive to moths.

“The reason that light pollution is bad is it disorients the moths,” Slatten said. “They’ll just continue to circle the light. When they’re doing that, they’re not visiting and pollinating those night-blooming flowers. The life cycle ends there. That’s what you’re trying to avoid.”

With summer just around the corner, it will soon be warm enough to head outdoors and enjoy your garden after dark. Turn the lights off, sit quietly and observe the secret workings of the nocturnal world, keeping a keen eye out for magical moths.

Monika Spykerman: 360-735-4556; monika.spykeman@columbian.com