Oenothera macrocarpa.
Missouri Evening Primrose is a perennial wildflower native to the southern and central United States.
Plant grows to a height of about 1 foot and produces large, bright-yellow flowers that are 3 to 4 inches in width—nearly the size of your hand!
Blooming is a singular event, meaning the flowers open in late afternoon, remain open throughout the night, and fade away come sunrise. Don't worry, though! The Missouri Evening Primrose has a long bloom period, prolific flowers, and easily self-seeds, so they're certain to give you an excellent nightly showing despite the short lived blooms.
Attracts Sphinx months and other pollinators. Typically blooms in the second year.
Missouri Evening Primrose
Growth Chart
Hardiness Zones: 5 to 9 Light Requirement: Full to partial sun Soil Type: Dry, sandy, gravelly Sow Depth: Surface Plant Spacing: 18 inches Germination Note: Cold stratification required Stratification Time: 60 days Bloom Time: May through August Growing Tips
Direct sow in early spring by lightly pressing the seeds into the soil's surface. Keep soil lightly moist until germination, which should occur within 10-30 days. When the seedlings are sturdy enough to be safely be handled, thin for wider spacing.
A Note on Cold Stratification
These seeds require cold, moist stratification. To naturally stratify the seeds, plant outdoors late fall on a weed-free site and allow seeds to overwinter.
To artificially stratify the seeds, place the seeds and a moist medium (such as a damp paper towel, coffee filter, sand, or vermiculite) in a labeled, sealed plastic bag and store in a refrigerator (33-40°F) for the amount of time noted on the growth chart before sowing.