When, Where and How to Grow Mexican Evening Primrose
Mexican Evening Primrose
Most Will Bloom During the Day
Although they are called evening primrose (Oenothera biennis), some of these showy pink, yellow or white flowers bloom in the daytime, and butterflies, bees, and birds love them.
Most gardeners grow primrose flowers as annuals, although they can also be biennials or perennials, and they bloom from early spring all the way to fall. They belong to the Oenothera genus, which is native to the Americas and contains about 145 herbaceous plant species. Besides the evening primrose, common names of these species include pink ladies, snowdrops and sundrops.
If you have a rock garden, there are few plants more suited for such a location. They will thrive in full sun and light and sandy soil, which is what we have here in the Albuquerque, New Mexico, area. As you can see from the photographs, they produce open, cup-shaped flowers.
When to Plant
If you desire your primrose flowers to bloom in the first planting year, you have to sow the seeds in the fall. You could also start them indoors early in the spring, then transplant them outside after the last frost.
The young plants will begin to form rosettes, which will then produce flowering stems. If you start your seeds in the fall they will produce the rosettes but will die back during heavy frost only to re-emerge in the spring.
Primrose plants are aggressive and will spread if they are not properly controlled. The ones you want to remove should be pulled up by their roots.
These plants are hardy in USDA growing zones 3-8. If you are in zone 9 or 10, the evening primrose should be planted in late winter or early spring and will behave as an annual.
If you want to keep your primrose plants looking great, make sure your regularly prune the dead leaves and spent blooms.
Where to Plant
These plants will do their very best when planted in a location that receives partial shade, and the closest you can come to providing a forest-like environment, the better off you will be. Think moist, rich soil in dappled sunlight. The one thing that will make your primroses behave as annuals is their placement in the hot, direct sunlight. Such placement will keep them from coming back in subsequent years. Your area should drain well.
How to Plant
If you buy a primrose plant at a nursery or garden center, try to find a healthy-looking one with unopened buds.
You should keep at least six inches between the plants and the plant's base should be even with the soil. If you are planting seeds, place them about 4-6 inches deep and water them thoroughly. If you have transplanted small plants from indoors, they should have at least an inch of water per week. You can conserve the moisture by applying a leafy compost around the plants, which will also serve to keep the soil cool and provide the nutrients your plants need. Doing so should eliminate the need for additional fertilizer.
Throughout the summer months, continue to water them about once a week (more during periods of drought). When fall approaches, you can let up on the watering.
Growing Primrose From Seeds
You can grow primroses indoors or outdoors (depending on the time of the year and the climate in your area) from seeds by placing them in an equal mixture of sand, soil and peat moss. Usually, the seeds are sown indoors during the colder months of winter or outdoors in a cold frame protected from ice and snow. When the seedlings have their second or third leaves, you can transplant them out into the garden.
Pests and Other Potential Problems
You could encounter slugs and snails trying to invade your primrose plants but they can be controlled in many different ways such as placing a nontoxic slug bait near the plants.
Aphids and spider mites can be sprayed with soapy water if you find them on your primrose plants.
If the area in which they are planted doesn't drain well, your plant may be susceptible to root rot or crown rot. If this becomes a problem, you will need to either amend your soil with compost or relocate the plants to another area that drains well. Poor drainage also can lead to fungal infections. Primroses will not grow properly if their roots stay wet.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Mike and Dorothy McKenney