10" x 18-24" wide, (seed propagated). (Botanists have changed the name for this species from missouriensis to macrocarpa). This native wildflower is renowned for the huge 4" yellow flowers that open each afternoon and close up the following morning. Long blooming throughout the summer months, it keeps going until it feels it has set enough seed pods to retire for the season. Long-lived, it forms a huge underground tuber to keep itself going from year to year. Evening Primrose cascades nicely over rocks and retaining walls. Zones 4-8. 5" deep Premium pot.