Medicinal plants

Evening Primrose (Oenothera biennis)

The only drawback is that its life cycle is biennial, that is, during the first year it germinates and grows, and the second one blooms, bears fruit… and dries up. But no, not everything is so bad: the seeds germinate very easily . Get to know it thoroughly.

Origin and characteristics of evening primrose

It is, as we said, a biennial herbaceous plant native to central and eastern North America; specifically, you can find it growing wild from western Alberta (in Canada) to southeast Florida and southwest Texas; Also, you should know that it has become naturalized in temperate and subtropical regions, so it would not be unusual for you to see it growing and surviving without problems outside the American continent. Its scientific name is Oenothera biennis, and it is known as enotera, ass grass, wine grass or evening primrose.

It reaches a height of between 30 and 150 centimeters, with lanceolate leaves 5 to 20cm long by 1-2.5cm wide that form a basal rosette the first year. Throughout the following spring, it produces a long spike of yellow or orange flowers measuring 2.5 to 5cm in diameter, and consisting of four petals. These open at dusk and close around the following noon.

The fruit is a capsule 2 to 4cm long by 4 to 6mm wide, which contains numerous seeds 1 to 2mm long that are released when the fruit opens into four sections or valves when it finishes maturing.

What are the care it requires?

If you want to have a copy, we recommend that you take care of it as follows:


Ideally, it should be in full sun, but it can grow in semi-shade as long as the area is bright (that is, there is more light than shade).


It is not demanding, however we advise the following:

  • Pot: mix universal substrate with perlite in equal parts. You can get the first here and the second here.
  • Garden: grows very well in fertile, well-drained soils. In the event that yours has a great tendency to compact or that it has very poor water absorption and filtration capacity, make a planting hole of about 50 x 50cm, cover its sides with a shading mesh, then put a layer of about 5cm of fine gravel (about 3-5mm) or clay, and finally finish filling with the mixture of substrates mentioned before.


Rather rare. It is a plant that fears excess humidity, and that, on the contrary, resists drought relatively well. To avoid taking unnecessary risks, check the humidity of the soil before watering, at least the first few times.

You can do it with the classic stick (if when you take it out it comes out clean, it will be time to water), or if you have your evening primrose in a pot, weighing it once watered and again after a few days.


Taking into account that it has medicinal properties, and that its flowers are also pollinated by a great variety of insects as beneficial as bees, we recommend fertilizing it with organic and ecological products.

Related article:5 homemade fertilizers for your plants

If you grow it in a pot, liquid fertilizers are perfect, since precisely because they are liquid, they do not worsen the drainage of the substrate, such as liquid guano or seaweed fertilizer, always following the indications specified on the packaging. In the event that you have it on the ground, you can use granules or powder, such as herbivorous animal manure, compost, etc.


Evening primrose multiplies by seeds in spring, following this step by step:

  1. First, fill a seedbed (it can be a seedling tray (sold here ), a pot with drainage holes, milk containers (make a hole in the base), or something else) with seedbed substrate (sold here ).
  2. Then, water and place a maximum of two seeds in each socket or seedbed.
  3. Then cover them with a thin layer of substrate.
  4. Then, water with a sprayer to moisten the surface layer of the substrate.
  5. Finally, place the seedbed outside, in semi-shade.

Thus they will germinate in about 10 days, as long as the substrate is kept moist.

Planting or transplanting time

In spring, when the risk of frost has passed.


Evening primrose resists up to -8ºC.

For what do you use it?


It is a very decorative plant that can be kept in pots, planters or on the ground. It does not require much care, and as it resists frost and high temperatures (not extreme) it lives in a wide variety of climates.

Medicinal – Evening primrose oil

From the seeds, after cold pressing, an oil rich in essential fatty acids is obtained that the human body is not capable of producing but which are necessary to us, such as linoleic acid and gamma-linolenic acid.

This oil has analgesic properties during menstruation, and it helps to relieve the symptoms of menopause. But according to studies conducted by the Mayo Clinic (from the United States), its use is contraindicated in people suffering from epilepsy.

Where to buy evening primrose?

You can buy it in nurseries, garden stores, or from here:

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