Evening Primrose
Oenothera biennis
Give it drainage and room: the roots rot in wet ground, and the seedlings take over wherever they are tolerated.
- Type
- Flower · Grown as a biennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Flower color
- Yellow
- Sunlight
- Full sun
- Feeding
- Rose & flower
- Frost tolerant
- Yes
- Flowering
- June
- Mar–Jun Spring Growth
- Jun–Sep Flowering
- Sep–Nov Growing
- Nov–Dec Leaf Fall
- Jan–Mar Leaf Fall
- Plant spacing
- 17.7 in
- In-row spacing
- 17.7 in
- Between rows
- 22 in
- Square-foot density
- Not suited to SFG
- Root system
- A slender taproot with fine side roots
- Working depth
- 18 in–3 ft
- Can reach
- 4 ft down where the soil allows
- Spread
- 9–18 in across, about 0.5–1× the width of the plant
- Shallowest pot
- 16 in of soil
The taproot goes down before the plant does much above ground, and it never forgives being broken. Sow it where it is to grow, or start it in a deep cell and plant it out before the root reaches the bottom.
The habit is Evening Primrose’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
Verbascum, Grasses, Achillea, Echinacea
Green-leaved flowers, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com