Evening primrose (common evening primrose)

About Evening primrose (common evening primrose)

Common evening primrose is a native biennial: a leafy rosette the first year, then 3-7 foot stalks of yellow flowers that open at dusk. Night-flying moths pollinate it, hummingbirds visit, and many birds eat the seeds. Its seeds are the source of evening primrose oil.

Hardy in zones 4-9 (NC State); each plant flowers in its second summer and then dies, but it reseeds freely.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Easy to grow from seed, which sprouts within about four weeks; plants bloom in their second year and usually self-sow (NRCS). Seed can stay alive in the soil for decades (NC State).

Soil

Well-drained soil of almost any kind, including gravelly, rocky, sandy or clay soil; it is very drought tolerant.

Plant in well-drained soil in full sun or light afternoon shade; it grows even in gravelly, rocky or clay soil and is very drought tolerant.

Feeding

It self-sows freely and seed lasts for years in the soil, so pull unwanted seedlings early.

Harvest

Flowers open at dusk and close the next day, June to September. It spreads by self-seeding, so pull extra seedlings to keep it in bounds.

Diseases and problems

Leaf spot, Powdery mildew

In the kitchen

The roots were boiled and eaten like potatoes, and young leaves were cooked as greens (NRCS).

Safety: Evening primrose oil can cause stomach upset and headaches, and it may raise bleeding risk with blood thinners such as warfarin (MSKCC). NCCIH says it may be safe in pregnancy but the evidence is not conclusive, while MSKCC advises pregnant women not to take it, so ask a doctor first.

Pets: Not listed by the ASPCA; its 'Primrose' entry is a different plant (Primula vulgaris), which it lists as toxic to dogs, cats and horses.