The common evening primrose (Oenothera biennis) is a native wildflower in most of the U.S. It is found naturally in sunny fields, roadsides, prairies, and disturbed areas. Common evening primrose can also be grown in the garden as a native wildflower. It is a biennial, meaning that it lives for two years and only blooms during the second year, but will readily self-seed and come back from seed year after year.
For the first year, common evening primrose produces a rosette of leaves and puts most of its energy into establishing its root system. The second year it will send up a 3-5 foot tall leafy stalk that will end in a cluster of bright yellow flowers. In open, sunny areas the main stem may even produce smaller side-branches that can also bloom and create an almost bushy appearance. In Kentucky, common evening primrose blooms from July to October.
Common evening primrose gets its name from the fact that it blooms in the evening. Shortly before sunset the flowers will slowly unfurl. You can actually watch this happening over a period of 5-10 minutes. The flower will then remain open all night and produce a lemony scent. By mid-day the flowers will close. Each flower typically only lasts a single day, two at the most.
Sphinx moths are thought to be the primary pollinators of common evening primrose. At least one species of native sweat bee also relies on evening primroses. The evening primrose sweat bee (Lasioglossum oenotherae) is active very late in the day and only gathers evening primrose pollen for its brood. One resource indicated that the evening primrose sweat bee may be active all night on bright, moonlit nights when the evening primroses are open.
Hummingbirds, butterflies, honey bees, bumblebees, and several other species of native bees will visit the flowers when they are open during daylight hours. The flower buds and foliage are also important foods for the caterpillars of several moth species including the primrose moth (Schinia florida) which as a caterpillar can only eat the flower buds of plants in the genus Oenothera. Goldfinches and other songbirds will eat the small seeds once the seedpods form.
Common evening primrose grows well in medium to dry soils and doesn’t mind gravelly or sandy soils which makes it a good option for “problem areas” in the landscape. When planting in a garden setting, try planting shorter things in front of it because the lower leaves may fall off during droughts. Because common evening primrose self-seeds, it can sometimes become somewhat weedy in garden settings. If this happens, simply pull the extra seedlings or remove the seedpods before they open. Just remember if you remove the seedpods, then you will need to plant some of those seeds if you want to keep it coming back in future years.
This article was part of Shannon’s original Kentucky Pollinators and Backyard Wildlife blog which evolved into the blog for Backyard Ecology.
Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.