Evening Primrose – Oenothera biennis

Evening primroses are generally known as flowers that close during daylight hours. Evening primroses are beautiful flowers and easy to grow. They open visibly fast every evening, producing an interesting evening spectacle, hence the name “evening primrose.”

Common Evening Primrose is a biennial plant. In the first year, it typically produces a basal rosette of light green leaves but no flowers. In the second year, a stiffly-upright, purple-tinged flower stem rises from the center of the rosettel, topped by a showy bloom of bowl-shaped, lemon yellow flowers. The flowers open at dusk and close again in the morning when hit by sun. It can reach heights of 6′ in the right conditions but is often shorter. It is one of the last natives blooming late into fall. Once it completes its two-year life cycle, it will re-seed. 

Pollinators

Common Evening Primrose’s long bloom time benefits many pollinators. The flowers are fertilized by night-flying moths, which are attracted by the mild lemon flower fragrance and by bees in the early morning before closure. Much of the life cycle of the stunning pink Primrose Moth can be in the Common Evening Primrose plant.  The small green larvae of the Primrose Moth will feed on the flowers and seed of the plant and the adult moth can often be found resting on the yellow flowers, pollinating them in the process. Other occasional visitors include the Ruby-Throated hummingbird, bumblebees, and miner bees. The caterpillars of several moths and various beetles feed on the foliage. The seeds are eaten by goldfinches.

Where to Plant Primroses

In its natural habitat, you’ll find primroses on rocky or sandy soils. They can be found in clearings, sandy roadsides, along railways.

It is a biennial that is suitable for beds and borders, wildflowers, cottage gardens, and herb gardens. They enjoy moderate shade and are frequently planted in groups under deciduous trees or in sites with north-facing sun exposure. Plants in chilly northern regions may require greater light exposure. Primroses can be planted in areas where you want to attract a variety of moths, small animals, birds (including hummingbirds), deer, and nocturnal bees.

This lemon-scented flower is perfect for moon gardens as it blooms in the evening. Although it is a night bloomer, it still requires sunlight in the day.

Propagation

From seed

Primrose seeds require stratification, which is a ‘cold’ period, in order to germinate. For germinating seeds and establishing seedlings, cool temperatures of roughly 10 degrees Celsius are typically recommended. Consider starting seedlings inside a refrigerator. Sow them outside in the fall in full light with loose soil. Sow the seed on top of the soil and water well.

Keep in mind that they are biennials and will not flower in the first year.

Self Sowing

Many cultivars will self-sow outdoors. They have a tendency to spread and may take over your garden if not maintained. It is considered a weed to some due to its invasiveness.

By Division

After flowering, primrose may be easily removed and divided in the garden, which may be the only way to preserve the genetic integrity of some hybrids. Primroses are frequently simple to transplant. Crowns should be planted at soil level and at least 15 cm apart.

Caring for Evening Primrose

Evening primrose are easily grown in full sun on average, medium moisture, well-drained soils, growing nicely in sandy or gravelly soils. They have a tendency to spread throughout the landscape by self-seeding in a weedy manner.

If you find that its leaves are brownish, it may have been overwatered and is suffering from root rot. Because this plant loves lower temperatures, plant it in early spring to avoid it growing lanky or weed-like. Fertilizer isn’t required. Most primroses are sensitive to summer heat and dryness. To keep its roots cool, apply a thick layer of mulch.

Daylilies and heleniums with complementary colours and flower styles are suggested as companion plants.

Pruning Onagre bisannuelle.

After flowering, remove the pedicel of the evening primrose flower to reduce nutrient loss and stimulate new branch development. Also remove wasted dry and dead branches.

Medicinal

The oil from the seed is added to skin preparations and cosmetics. It is often combined with vitamin E to prevent oxidation. A yellow dye is obtained from the flowers. A finely ground powder made from the flowering stems is used cosmetically in face-masks to counteract reddened skins. It can also be used to treat asthma, migraines, eczema, inflammation, PMS, high cholesterol and more.

Evening primrose can help with a variety of skin conditions, such as acne and it may also promote hair growth. The flowers are also edible raw or cooked, and are sometimes used in salads.

Toxicity to Pets

Evening primrose, Oenothera biennis, is widespread in eastern and central North America from Newfoundland to Alberta, southeast to Florida, and southwest to Texas. It is not poisonous to dogs or cats.

However, the ASPCA warns that common primrose, Primula vulgaris, a plant native to Europe, is toxic to cats, horses, and dogs. In cats, it typically causes mild to moderate gastrointestinal discomfort. The exact harmful chemical found in the plant is unclear.

Other

You can expect to see various traditional garden pests, including mealybugs, spider mites, and aphids. If you notice signs of infection, treat them with insecticidal soap or neem oil.

Both First Nations and settlers used evening-primrose for several medicinal purposes. They treated wounds and bruises with a poultice of leaves, while a tea or infusion of the plant was drunk to soothe coughs and digestive complaints.