Zone: 3 to 9
Soil: Sand to loam
Light: Full sun to part sun
Bloom colour: Yellow
Bloom period: late spring to early summer
Height: 2 to 6 feet
Moisture: Dry to medium
Attracts: Bees and sphinx moths.
Notes: It is hard to generalise about the members of this genus because there are so many species. Typically, the species seen in Ontario do well on freely drained soils. The moisture requirements vary considerably by species. Sundrops are great plants for a garden as they often have a carpet of flowers that cover relatively short stems. This makes these plants highly desirable in an ornamental garden.
Unfortunately, Common Evening Primrose, which is the species in nature most often seen, is not that great for a suburban garden. Only a few flowers are open at a time and the plant, growing to over 6 feet, is rather lanky looking. Being a true evening primrose, the flowers are fully open in the evening when we are not actually looking at our flowers. It is reported that these plants are pollinated by sphinx moths although I have not been able to verify this personally.
Better plants for a garden include Oenothera pilosella and Oenothera fruticosa. These plants are particularly showy and I use them as accent plants. As they are only in flower for a few weeks, they are not the mainstay of the garden. The former plant is also called Prairie Sundrops and grows well in dry sandy as well as moist soil.