North America Native Plant

Smooth Four O’clock

Botanical name: Mirabilis glabra

USDA symbol: MIGL3

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Allionia carletonii Standl. (ALCA13)  âš˜  Allionia ciliata Standl. (ALCI2)  âš˜  Allionia exaltata Standl. (ALEX)  âš˜  Allionia glabra (S. Watson) Kuntze (ALGL7)  âš˜  Mirabilis carletonii (Standl.) Standl. (MICA4)  âš˜  Mirabilis ciliata (Standl.) Shinners (MICI)  âš˜  Mirabilis exaltata (Standl.) Standl. (MIEX2)  âš˜  Oxybaphus carletonii (Standl.) Weath. (OXCA6)  âš˜  Oxybaphus exaltatus (Standl.) Weath. (OXEX)  âš˜  Oxybaphus glaber S. Watson (OXGL7)   

Smooth Four O’Clock: A Native Evening Bloomer for Your Garden If you’re looking for a native plant that puts on a show when most others are calling it a day, meet the smooth four o’clock (Mirabilis glabra). This charming perennial herb brings color and life to your garden during those ...

Rare plant alert!

Region: Conservation status by state

Status: S3S4Q: Status is uncertain but is somewhere between the following rankings: Uncertain taxonomy: ⚘ Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Smooth Four O’Clock: A Native Evening Bloomer for Your Garden

If you’re looking for a native plant that puts on a show when most others are calling it a day, meet the smooth four o’clock (Mirabilis glabra). This charming perennial herb brings color and life to your garden during those magical evening hours when the day’s heat starts to fade.

What is Smooth Four O’Clock?

Smooth four o’clock is a native perennial forb that belongs to the four o’clock family. Unlike woody shrubs or trees, this herbaceous plant dies back to the ground each winter and reemerges from its roots come spring. Its smooth stems and heart-shaped leaves create an attractive backdrop for its real star feature: tubular pink to magenta flowers that open in late afternoon and evening.

You might also encounter this plant under several other botanical names in older references, including Oxybaphus glaber and various Allionia species, but Mirabilis glabra is the current accepted name.

Where Does It Grow Naturally?

This native beauty calls the American Southwest and south-central plains home. You’ll find wild populations across Arizona, Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, and Utah. It’s perfectly adapted to the challenging conditions of these regions, from high desert plains to prairie grasslands.

Why Consider Smooth Four O’Clock for Your Garden?

There are several compelling reasons to give this native plant a spot in your landscape:

  • Evening garden interest: When most flowers close up shop for the day, smooth four o’clock is just getting started
  • Pollinator magnet: The evening blooming time attracts sphinx moths and other night-flying pollinators, plus hummingbirds love the tubular flowers
  • Drought tolerance: Once established, this plant can handle dry conditions like a champ
  • Low maintenance: Native plants are naturally adapted to local conditions, meaning less work for you
  • Wildlife support: Native plants provide better habitat and food sources for local wildlife than non-natives

A Note on Conservation

Before you rush out to find this plant, there’s something important to know. Smooth four o’clock has a conservation status that suggests it may be somewhat uncommon in parts of its range. This doesn’t mean you shouldn’t grow it – quite the opposite! Growing native plants in our gardens can help support these species. However, it does mean you should be thoughtful about sourcing.

Always purchase from reputable native plant nurseries that grow their stock from seed rather than wild-collecting. Avoid digging plants from the wild, which can harm natural populations.

Growing Conditions and Care

The beauty of native plants like smooth four o’clock is that they’re already adapted to succeed in your region’s climate. Here’s what this plant prefers:

  • Sunlight: Full sun for best flowering
  • Soil: Well-draining soil; it’s not picky about soil type but can’t tolerate waterlogged conditions
  • Water: Drought tolerant once established, but appreciates occasional watering during extended dry spells
  • Climate zones: Hardy in USDA zones 4-8, covering most of its native range

Perfect Garden Settings

Smooth four o’clock shines in several garden styles:

  • Native plant gardens: Pairs beautifully with other regional natives
  • Xeriscaping: Perfect for water-wise landscaping
  • Prairie or wildflower meadows: Adds evening interest to naturalized areas
  • Evening gardens: Ideal for spaces you enjoy during sunset hours

Planting and Care Tips

Getting smooth four o’clock established in your garden is straightforward:

  • Plant in spring after the last frost date
  • Space plants about 18-24 inches apart
  • Water regularly the first growing season to help establish deep roots
  • After establishment, water only during prolonged drought
  • No fertilizer needed – native plants prefer lean soils
  • Allow plants to go to seed if you want them to self-sow
  • Cut back in late fall or early spring before new growth emerges

The Evening Show

Perhaps the most delightful aspect of smooth four o’clock is its timing. As the name suggests, the flowers typically open around 4 PM and stay open through the night. This makes it perfect for gardeners who want to enjoy their outdoor spaces during the cooler evening hours. The sweet fragrance that often accompanies the blooms is an added bonus that attracts night-flying pollinators.

Is Smooth Four O’Clock Right for Your Garden?

If you live within its native range and have a sunny spot with good drainage, smooth four o’clock could be a wonderful addition to your landscape. It’s especially valuable if you:

  • Want to support native plant conservation
  • Enjoy your garden in the evening hours
  • Are creating a drought-tolerant landscape
  • Want to attract night-flying pollinators and hummingbirds
  • Appreciate low-maintenance plants

Remember to source your plants responsibly, and you’ll have a beautiful native that connects your garden to the natural heritage of your region while providing habitat for local wildlife. Sometimes the best garden additions are the ones that have been thriving in your area for thousands of years – they just needed an invitation to join your landscape party!

Smooth Four O’clock

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Caryophyllidae

Order

Caryophyllales

Family

Nyctaginaceae Juss. - Four o'clock family

Genus

Mirabilis L. - four o'clock

Species

Mirabilis glabra (S. Watson) Standl. - smooth four o'clock

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA