Actual size and flowering may vary slightly based on season.
Mexican Evening Primrose
Mexican evening primrose is a low, fast-spreading groundcover with bright pink, cup-shaped flowers that open in the morning and stay open all day. It blooms heavily in early spring and keeps flowering through the warm season with some water. It stays about 6 to 12 inches tall and spreads by underground stems, so it quickly covers slopes and open ground.
Best for: slopes and banks, big informal areas, and rocky, dry ground where it can roam.
It spreads quickly by underground stems, which makes it useful for holding soil on banks and slopes. Each plant spreads 2 to 3 feet, so a few plants cover a bank fast.
Give it open ground and it fills in with pink flowers each spring. It suits spots where you are happy to let it roam.
Once rooted it can live on rainfall, and it spreads much more slowly in rocky native soil with no water. A little extra water gives more flowers and greener growth.
It grows aggressively and can invade beds that get regular water. It can be hard to remove once settled, so plant it only where it can be contained.
- Quick cover15-18 in apart, center to center
- Plant to plant26 in apart, center to center
For the first two weeks, water a new plant every 1 to 2 days in summer, or every 3 to 4 days in cooler months. Then stretch the time between waterings. Once rooted it is low water, and some water through the warm season keeps it flowering, but it does not like to be overwatered.
It spreads by underground stems and seed. Limit water to keep it in bounds, and use care next to watered beds, where it can take over.
Cut rangy, overgrown or frost-damaged plants to the ground. It regrows quickly from underground stems, and a spring trim keeps its size in check.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
How much does it spread?
It spreads quickly by underground stems and seed, with each plant reaching 2 to 3 feet. Near watered beds it can take over, so plant it where it can roam.
Is it hard to get rid of?
It can be hard to remove once it has settled in, because it spreads underground. Plant it only where you want a groundcover.
How do I keep it in check?
The amount of water you give it controls it. It spreads fast in moist, amended soil and much less in rocky native soil with no water, so keep it away from irrigated beds.
When does it bloom?
It blooms heaviest in early spring and can keep flowering through the warm season with some water.
Why is it called evening primrose if it blooms in the day?
This one opens in early morning and stays open through the day, unlike some of its relatives. The flowers are open when you are out in the yard.
How tall does it get?
It stays low, about 6 to 12 inches tall, with each plant spreading 2 to 3 feet.
Is it cold hardy?
Yes. The tops can freeze to the ground below about 20°F, but it recovers quickly in spring from underground stems, so just cut back the dead growth.
It looks rangy. Can I cut it back?
Yes. Cut rangy, overgrown or frost-burned plants to the ground and they regrow quickly. A trim in spring also keeps its size in check.
How often should I water it?
Water a new plant every 2 to 4 days for the first few weeks, then stretch it out. Once rooted it can live on rainfall, and occasional summer water gives more flowers.
Does it attract wildlife?
Yes. Insects and moths visit the flowers, and songbirds eat the seeds. Leave some seed heads if you want to feed the birds.
Mexican Evening Primrose for sale in Arizona, delivered to you
Mexican evening primrose is a tough pink groundcover for Valley slopes and open ground. It blooms heavily in spring on little water. Below are the questions people ask most, including how to keep it where you want it.
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Is Mexican evening primrose invasive?
It spreads aggressively by underground stems and can invade nearby beds, especially watered ones. Plant it only where it can be contained, like slopes and open ground.
Mexican evening primrose for slopes
Its spreading underground stems hold soil, which makes it useful on banks and slopes where you want fast, low cover.
How to control evening primrose
Limit water and plant it away from irrigated beds. Cutting it back to the ground resets rangy plants.
When does Mexican evening primrose bloom?
It blooms heaviest in early spring and keeps flowering through the warm season with some water. The flowers open in the morning and stay open all day.
Cold and frost
The tops can freeze to the ground below about 20°F, but it regrows quickly from underground stems in spring.
Watering Mexican evening primrose in Phoenix
Once rooted it can survive on rainfall. Occasional water gives more flowers and greener growth, but more water also means more spreading.
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