Trailing Cup-Flower, White Cup
Set out plants in late spring (after any danger of frost has passed), 8 to 12 inches apart, in filtered sun or partial shade. Choose a sandy loam that is moist but well-drained. A sunny or lightly shaded site is best.
Keep Nierembergia well watered throughout the growing season, particularly during periods of extended drought. In zones 6 and 7 a winter mulch will help assure hardiness, though it is not reliably hardy north of New York City. Trim back after flowering to encourage bushy growth.
Zones 7-9 (warm areas of 6)