The evening primrose is an herb-like perennial plant that usually grows up to 19 1/2 inches tall but can sometimes reach heights of 4 to 5 feet. The evening primrose has hairy leaves that emit a lemon odor and bright yellow, 2 1/2-inch wide flower spikes that bloom in the evening and close during the daytime. The evening primrose blooms throughout the summer and autumn. The entire plant is edible and often used for medicinal purposes. The oils in the plant's seeds contain gamma-linolenic acid (GLA), an essential fatty acid.
Plant your evening primrose in the winter, in full sunlight and fertile, well-draining soil. If you're planting multiple evening primroses, space the plants about 1 1/2 to 2 feet apart.
Water your evening primrose once or twice each week to supplement rainfall during the growing season to keep the soil slightly moist at all times. Wait until the top 1 to 2 inches of soil dries before watering.
Feed your evening primrose an all-purpose, liquid flower fertilizer once each month throughout the growing season.
Prune away any crowded stems. Cut back the evening primrose after it finishes flowering and remove the spent blooms to promote re-blooming.