Actual size and flowering may vary slightly based on season.
Moss Verbena
Moss verbena is a low, fast-spreading groundcover with fine, lacy leaves and clusters of purple flowers for much of the year. It stays under a foot tall and spreads about 3 feet, so a few plants cover a bare bed or slope quickly. Butterflies come to the flowers all season. Give it full sun to part sun, soil that drains, and regular water in summer.
Best for: fast color on open ground and slopes, butterfly gardens, and the edges of beds and rock gardens. A low, spreading plant with fine, lacy leaves and purple flowers for much of the year.
Each plant spreads about 3 feet and stays under a foot tall, filling open ground and slopes with fine, lacy green. For a groundcover, set plants about 3 to 4 feet apart. It helps hold soil on banks and slopes.
Clusters of purple flowers open for much of the year in the Valley, from spring through fall. Butterflies and other pollinators visit them all season.
At 6 to 12 inches tall it softens bed edges, spills between rocks and fills pots. Group plants about 2 feet apart for a fuller edge. A decomposed granite mulch around it suits it well.
Midsummer heat can leave it thin and leggy until fall. Soggy, poorly drained soil rots the roots, and it does not take foot traffic. It is short-lived, so expect to replace plants every few years.
- Group planting2 ft apart
- Groundcover3-4 ft apart
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, water about every 7 to 10 days in summer, every 10 to 14 days in spring and fall, and every 2 to 3 weeks in winter. Let the soil dry between waterings.
Trim it lightly during pauses in flowering, or in late winter or early spring.
It is short-lived and often declines after a few years. Many gardeners replace it every year or two.
Frost and freezes can damage it. Wait until frost danger has passed, then trim off the damaged growth.
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.
Why does my moss verbena look like it is dying in summer?
Peak heat makes it slow down, thin out or scorch. It usually rebounds as fall cools off. Trim it back lightly to push fresh growth and keep up regular summer water.
How long does moss verbena live?
It is often short-lived in the desert, commonly declining after 2 to 3 years. Plan to replace plants every few years to keep the bed full.
How often should I water moss verbena?
Water a new plant every few days for the first weeks. Once rooted, water about every 7 to 10 days in summer, every 10 to 14 days in spring and fall, and every 2 to 3 weeks in winter.
How big does moss verbena get?
It stays about 6 to 12 inches tall and spreads about 3 feet. Set plants about 3 to 4 feet apart for a groundcover, or 2 feet apart for a fuller group.
When does moss verbena bloom?
It blooms for much of the year in the Valley, from spring through fall. Flowering slows in peak summer and picks back up as it cools.
What is the white powder on the leaves?
That white powder is powdery mildew. It is unsightly but rarely kills the plant. Cut back the affected stems when milder weather returns.
Does moss verbena attract butterflies?
Yes. The purple flower clusters are a butterfly favorite all season.
Is moss verbena cold hardy?
It is rated to about 20°F, and hard frost can damage it. Wait until frost danger has passed, then trim off the damaged growth.
Can moss verbena take shade?
It grows in full sun to part sun. Keep it off the hot west side of the house, and give it soil that drains.
Moss Verbena for sale in Arizona, delivered to you
Moss verbena is one of the fastest ways to cover sunny ground with purple flowers in the Valley. It feeds butterflies, stays low, and blooms for much of the year, with a few summer quirks. Below are the questions people ask most, from watering and spacing to summer slumps and mildew.
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Moss verbena in a Phoenix summer
It can look thin or scorched in peak heat and bounces back as fall cools. Trim tired stems lightly and keep up regular summer water to reset it.
How often to water moss verbena
Once rooted, water about every 7 to 10 days in summer and every 2 to 3 weeks in winter. Soggy soil rots it, so let the soil dry between waterings.
How fast does moss verbena spread?
It spreads quickly across open ground. Each plant covers about 3 feet and stays 6 to 12 inches tall.
How far apart do you plant moss verbena?
For a groundcover, set plants about 3 to 4 feet apart center to center. For a fuller group along an edge, plant them about 2 feet apart.
Moss verbena and butterflies
Purple flowers from spring through fall bring butterflies and other pollinators.
How long does moss verbena last?
It is often short-lived in the desert, typically 2 to 3 years. Replace plants as they fade to keep the bed covered.
Powdery mildew on moss verbena
White powder on the leaves rarely kills it. Cut back the affected stems when milder weather returns.
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