Evening Primrose
Planting Instructions
🌼 Overview of Oenothera biennis (Common Evening Primrose)
Native Range: Widespread across most of the United States
Life Cycle: Biennial (first year: basal rosette; second year: flowering and seed production)
Height: 3–6 feet in second year
Bloom Time: Midsummer to fall (second year)
Ecological Value: Excellent for pollinators (moths, bees, butterflies) and night-blooming wildlife gardens
Medicinal and edible uses: Roots, seeds, and leaves have traditional uses
🌱 Sowing Options
1️⃣ Direct Sowing Outdoors
Best Time to Sow:
Fall (preferred): Natural cold stratification improves germination.
Spring: Also possible, but pre-treatment with stratification improves results.
Site Selection:
Sunlight: Full sun (6–8 hours/day minimum); tolerates light shade.
Soil: Adaptable to many soils—well-drained loam, sand, clay, or gravelly soil.
Prefers poor to moderately fertile soil.
Soil pH: Neutral to slightly acidic (6.0–7.0)
Soil Preparation:
Loosen soil to about 6–8 inches deep.
Remove weeds and rake smooth.
No fertilization needed — excessive nutrients can cause leggy growth.
Planting Depth:
Surface sow or press into soil lightly.
Seeds need light to germinate—do not bury deeply.
If covering, use a dusting of fine soil or sand (~1/16 inch).
Watering:
Gently water after sowing.
Keep soil lightly moist until germination (10–30 days depending on conditions).
Once established, drought-tolerant, needs only occasional watering.
Stratification:
Recommended but not strictly required.
For spring sowing: cold-moist stratification for 30–60 days enhances germination.
Fall sowing provides natural stratification over winter.
Scarification:
Not necessary.
2️⃣ Starting Seeds Indoors (for Spring Transplanting)
When to Start:
6–8 weeks before last frost, after completing 30–60 days of cold stratification in moist medium in the refrigerator.
Growing Setup:
Use seed trays or small pots with well-draining seed-starting mix.
Surface sow or press seeds lightly onto the soil.
Maintain light and warmth (~65–75°F).
Provide bright light (12–16 hours/day) using a sunny window or grow lights.
Watering Indoors:
Keep soil moist (not wet) using misting or bottom-watering.
Transplanting Outdoors:
Harden off for 7–10 days before transplanting after frost risk passes.
Transplant in full sun at 12–18 inches spacing.
🔧 Maintenance Tips
Low-maintenance biennial — will reseed and naturalize easily.
Water during prolonged droughts, especially in first year.
Does not require fertilizer.
Remove seed heads to limit reseeding, or allow some to self-sow.
Often grown for wildflower meadows, pollinator gardens, and roadside plantings.
🚫 Invasiveness
Not considered invasive in native range, but can self-seed prolifically.
In garden settings, may spread beyond intended area if seed heads are not removed.
Easy to control by deadheading or cutting down before seeds mature.
