Common evening primrose

Sun

Full sun; tolerates light partial shade but flowers best in an open position.

Water

Low to moderate; water seedlings while they establish, then water only during prolonged dry spells.

Soil

Well-drained sandy, gravelly or loamy soil, including relatively poor ground; avoid soil that stays wet in winter.

Height

3-6 ft (0.9-1.8 m)

Spread

1-3 ft (0.3-0.9 m)

Flowers

Yellow flowers from summer into early autumn; individual flowers open towards evening and usually fade the following day.

Foliage

A first-year rosette of long, narrow green leaves, followed by leafy upright stems; leaves often have a pale or reddish midrib.

Growth

Fast once flowering stems develop in the second year.

Care needed

Low

• Pollinators
• Drought tolerant
• Cold hardy
• Heat tolerant
• Wildlife
• Low allergen
• Fragrant

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   2.8 ft (0.84 m)

3. After 2 years

   4 ft (1.4 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US and Canada

Invasive in

Australia

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Water newly sown patches gently until seedlings are established; avoid keeping the soil constantly wet.
• Do not routinely feed; rich soil can produce tall, floppy stems.
• Thin seedlings to roughly 18-24 in (45-60 cm) apart.
• Stake tall flowering stems early if the site is exposed to wind.
• Remove unwanted seedlings while small, before their taproots become difficult to lift.

Pruning. Remove spent flower spikes before the capsules ripen if you want to limit self-seeding. Otherwise leave some seedheads for birds, then cut the dead stems to ground level in late winter.

Spring

Sow seed thinly on prepared soil, pressing it into the surface with little or no covering.

Late spring

Thin seedlings and remove unwanted volunteers while their roots are small.

Early summer

Stake developing flowering stems where wind is likely to bend them.

Summer

Water young rosettes during prolonged drought; established plants usually need little extra water.

Late summer

Remove developing seed capsules to control spread, or leave a few selected stems to replenish the planting.

Late winter

Cut down dead stems, taking care not to damage overwintering rosettes.

• Place behind shorter plants in an informal sunny border for tall yellow flowering spikes.
• Combine with purple coneflowers, black-eyed Susans and grasses in a meadow-style planting.
• Use near an evening seating area where the opening flowers and their scent can be noticed.
• Let a few plants seed into a sunny gravel garden, removing excess seedlings to retain open space.

Garden styles it suits: Cottage garden, Wildflower, Wildlife garden, Pollinator garden, Dry gravel garden and Evening garden.

Plant it with: Purple coneflower, Black-eyed Susan, Little bluestem, Yarrow and New England aster.

Wildlife: The evening-opening flowers provide nectar for moths, including hawkmoths, and are also visited by bees. Seed-eating birds take the small seeds from mature capsules.

• Excessive self-seeding: remove flower spikes before capsules mature and pull unwanted seedlings promptly.
• Root or crown rot in wet soil: improve drainage or move the planting to a drier position; avoid heavy winter mulch over rosettes.
• Powdery mildew: thin crowded plants, keep roots from becoming severely drought-stressed and remove badly affected foliage.
• Slugs and snails eating young rosettes: inspect after dark, remove them by hand and protect seedlings where damage is persistent.

Not known to be toxic to people, cats, dogs or horses. No part is generally regarded as poisonous, although this does not make garden plants suitable as unrestricted food or livestock forage.

Where it spreads. Native to much of North America and naturalised in the UK and Australia. It can spread aggressively by seed on open, disturbed ground and is treated as an environmental weed in parts of southeastern Australia, including New South Wales and Victoria; check local guidance before planting near bushland.

• Large-flowered evening primrose (Oenothera glazioviana)

  Usually has noticeably larger yellow flowers and red-striped or reddish sepals around the buds. Identification can be difficult where evening primroses hybridise.

• Missouri evening primrose (Oenothera macrocarpa)

  A low, sprawling perennial with very large yellow flowers and conspicuously winged seed capsules, rather than tall upright flowering stems.

The species name biennis means two-year, referring to its usual biennial life cycle, while evening primrose describes its evening-opening flowers.

Propagation. Grow from seed sown directly outdoors in spring or early summer for flowering the following year. Press seed onto the soil surface, keep it lightly moist until germination and transplant only very young seedlings because older plants develop a substantial taproot.

Accepted botanical name

Oenothera biennis

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alabama, Alberta, Arkansas, British Columbia, California, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho and Illinois.

Measured

Soil pH 5 to 7. Average height 82 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.