(Oenothera glazioviana) [Introduced 1987 by SESE.] The large fragrant blooms burst open suddenly at dusk. The crisp, yellow, showy four-petalled flowers circle a spire of reddish, swollen buds. Blooms are 2/3 open within 10 seconds or less, and fully open within 1-2 minutes! Blooming lasts 5-6 weeks or more. Will bloom indoors as a cut flower for approximately a week. Dim lights to induce flowers to open indoors in the evening. Produces a flat rosette of leaves the first year, followed by 3-4 ft. yellow spires the second year. Very hardy. During the evening the flowers are pollinated by night-flying moths as large as hummingbirds. This variety was discovered by garden writer Tina James who hosts "primrose parties" every year. Makes an interesting container plant for a deck or balcony and is a great conversation piece.
Growing instructions: Biennial. Germination: 65-75°F, 14-21 days. Full sun. Sow May through July in pots or flats; transplant after several true leaves have developed. Space 16-18 in. apart. Ht. 36-48 in.
Read more about how Ms. Tina James shares the wonders of evening primroses in this Baltimore Sun article.