Welcoming Visitors to Our Night Garden

by Monica Coplea

Sacred Datura opens its large, showy flowers in the late afternoon and evening, and is often pollinated by sphinx moths. Photo courtesy of Monica Coplea

Night gardens are made up of plants that bloom and attract pollinators after dark. And no, they have nothing to do with “night soil”—that’s a whole other topic!

We often hear about conserving daytime pollinators like bees, but pollination doesn’t stop when the sun goes down. Nearly two-thirds of flowering plants rely on animal pollinators, and many plants continue their reproductive work at night. Some important crops, including apples, peaches, and blueberries, benefit from night-time pollination.

As the sun sets and daytime pollinators lose steam, another world comes alive. Some flowers close during the day and open in the evening - particularly plants adapted to dry climates. In places like Flagstaff, keeping flowers closed during the heat of the day helps reduce moisture loss. Once open, these flowers attract moths, nocturnal beetles, and flies. In warmer parts of Arizona, nectar-feeding bats also play an important role, although Flagstaff’s bats primarily eat insects.

The Night Shift

Sphinx moths, members of the family Sphingidae, act as key pollinators for deep-throated, night-blooming, fragrant flowers. Photo courtesy of Monica Coplea

One of Flagstaff’s most fascinating night pollinators is the sphinx moth, also called the hawk moth or hummingbird moth. The first time I saw one, I was admittedly a little freaked out—it looked like a mad scientist had created the Hulk of moths! With wingspans ranging from about two to eight inches and extraordinarily long feeding tubes, these moths are impressive creatures. They are the hummingbirds of the night, hovering over flowers as they feed. Their caterpillars, commonly called hornworms, can be destructive in the garden. Yet as adults, sphinx moths are important pollinators, helping ensure the reproduction and survival of many of the same plants they feed on as larvae.

Other moths, including numerous small species, are also important night-time pollinators. They are particularly attracted to pale-colored, strongly scented flowers. Moths can be remarkably efficient pollinators, often working quickly and visiting flowers that daytime pollinators overlook.

Nocturnal beetles are another group worth encouraging. Scarab and tumbling flower beetles are attracted to pale, strongly scented flowers, especially those with spicy or fermented scents. They also appreciate messy gardens with dead leaves and other organic matter where they can rummage and shelter.

Some flies contribute to night-time pollination as well. In Flagstaff, hover flies are especially common. They look like a cross between a bee and a fly and are most active around dusk, making them important pollinators of flowers that open in the evening.

Planting a Night Garden

When choosing plants for night pollinators, look for flowers that are light-colored, open at night, and strongly scented. Pale flowers reflect moonlight, making them easier for insects to find. Flower shape matters too: sphinx moths favor trumpet-shaped flowers, while beetles are often drawn to clustered blooms.

Whenever possible, choose native, non-invasive plants. Moonflower (Ipomoea sp.), for example, has many qualities that attract night pollinators, but it is closely related to bindweed, an invasive plant in many parts of the world. Always check whether a plant is appropriate for your area before adding it to your garden.

September is a good time of year to plant perennials. One native plant that perfectly demonstrates the qualities of a night-pollinator favorite is sacred datura. Its large white trumpet-shaped flowers open around sunset and release a sweet fragrance. In Flagstaff, the plant dies back in winter, but its deep roots survive and send up new growth in spring.

Evening primrose is another excellent choice. Hartweg evening primrose and white-stem evening primrose are two of several species native to the Flagstaff area, tolerate high elevations, and are drought resistant. Be careful when selecting varieties, however, as some non-native primroses can spread aggressively and crowd out other plants.

Other plants to consider include coyote tobacco, salvias such as Dorr’s sage and Mojave sage, coneflower, bee balm (wild bergamot), salt heliotrope,  yarrow, columbine,  yucca,

penstemon—a Flagstaff favorite—and milkweed, a favorite of many pollinators.

Turn Down the Lights

A night garden needs darkness. Bright outdoor lights can interfere with nocturnal pollinators, particularly moths, which instinctively gather around artificial light. This can disorient them, interfere with their natural rhythms, and increase their risk of exhaustion and death. Avoid pesticides whenever possible, especially if your goal is to attract insects. Providing shallow water, undisturbed soil, and areas of leaf litter and other organic material can also give night-time pollinators the food, shelter, and habitat they need. So as the sun goes down, resist the urge to turn on every light. Instead, take a moment to look around. Your garden may be much busier at night than you ever realized.

 Monica Copley, Master Gardener and all-around plant lover, has been a Flagstaff gardener since 2002. Gardening Etcetera is written for the community by certified Master Gardeners of the University of Arizona's Coconino County Cooperative Extension Master Gardener Program. Have a gardening question? Visit our Online Plant Help Desk at https://extension.arizona.edu/programs/coconino-county-master-gardener.