North America Native Plant

Hartweg’s Sundrops

Botanical name: Calylophus hartwegii hartwegii

USDA symbol: CAHAH

Life cycle: perennial

Habit: subshrub

Native status: Native to the lower 48 states  

Synonyms: Galpinsia hartwegii (Benth.) Britton (GAHA3)  âš˜  Oenothera hartwegii Benth. (OEHA3)  âš˜  Oenothera hartwegii Benth. var. typica Munz (OEHAT)  âš˜  Salpingia hartwegii (Benth.) Raimann (SAHA9)   

Hartweg’s Sundrops: A Bright Texas Native for Your Garden If you’re looking for a cheerful, low-maintenance native plant that can handle Texas heat and still put on a spectacular flower show, let me introduce you to Hartweg’s sundrops (Calylophus hartwegii hartwegii). This delightful little wildflower might just become your new ...

Hartweg’s Sundrops: A Bright Texas Native for Your Garden

If you’re looking for a cheerful, low-maintenance native plant that can handle Texas heat and still put on a spectacular flower show, let me introduce you to Hartweg’s sundrops (Calylophus hartwegii hartwegii). This delightful little wildflower might just become your new favorite ground cover – especially if you’re tired of babying plants that wilt at the first sign of summer!

What Makes Hartweg’s Sundrops Special

Hartweg’s sundrops is a perennial forb herb, which is just a fancy way of saying it’s a non-woody plant that comes back year after year. Don’t let the simple description fool you – this little powerhouse packs a serious punch in the beauty department. From spring through fall, it produces a steady stream of bright yellow, four-petaled flowers that seem to glow in the landscape.

The plant stays relatively low to the ground, making it perfect for areas where you want color without height. Its scientific name honors Karl Theodor Hartweg, a German botanist who collected plants in the Americas during the 1800s. You might also see this plant listed under some older botanical names like Oenothera hartwegii or Galpinsia hartwegii in older gardening references.

Where Does It Call Home?

Hartweg’s sundrops is a true Texas native, found naturally in the central and south-central parts of the Lone Star State. This plant has evolved to thrive in Texas conditions, which means it’s perfectly adapted to handle what Mother Nature throws at it – from scorching summers to occasional drought.

Why Your Garden (and Local Wildlife) Will Love It

There are several compelling reasons to consider adding Hartweg’s sundrops to your landscape:

  • Pollinator magnet: Those bright yellow flowers are like beacon signals for bees, butterflies, and other beneficial insects
  • Long blooming season: Enjoy flowers from spring through fall – that’s months of color!
  • Drought tolerant: Once established, this plant laughs in the face of dry spells
  • Low maintenance: Perfect for gardeners who want beauty without the fuss
  • Native benefits: Supporting local ecosystems while reducing the need for water and fertilizers

Perfect Garden Roles

Hartweg’s sundrops shines in several garden settings:

  • Rock gardens: Its low profile and drought tolerance make it ideal for rocky, well-draining spots
  • Ground cover: Fill in areas where grass struggles or where you want something more interesting than turf
  • Xeriscaping: A star player in water-wise landscaping designs
  • Native plant gardens: Essential for authentic Texas wildflower displays
  • Prairie restorations: Helps recreate natural Texas landscapes

Growing Hartweg’s Sundrops Successfully

The beauty of native plants is that they want to succeed in their home territory, and Hartweg’s sundrops is no exception. Here’s how to give it the best start:

Location and Conditions

Choose a spot with full sun – this plant needs at least 6-8 hours of direct sunlight daily to flower well. It’s happiest in USDA hardiness zones 8-10, which covers most of Texas and similar climates.

Soil Requirements

The most critical factor for success is well-draining soil. Hartweg’s sundrops can’t stand wet feet, so avoid areas where water pools after rain. It actually prefers alkaline soils, which is great news for Texas gardeners dealing with caliche or limestone-based soils that challenge other plants.

Planting Tips

  • Plant in spring after the last frost date
  • Space plants 12-18 inches apart if using multiple plants
  • Water regularly the first growing season to help establish roots
  • After establishment, water only during extended dry periods

Ongoing Care

This is where Hartweg’s sundrops really shines – it needs very little care once established. Skip the fertilizers (native plants don’t need them and may actually bloom less with too much nutrition). You can deadhead spent flowers to encourage more blooms, but it’s not necessary. The plant may self-seed, giving you more plants for free!

Is This Plant Right for You?

Hartweg’s sundrops is an excellent choice if you:

  • Live in Texas or a similar hot, dry climate
  • Want to support native wildlife and pollinators
  • Prefer low-maintenance plants
  • Need something for challenging, well-draining sites
  • Love bright, cheerful flowers

However, you might want to look elsewhere if you:

  • Live outside zones 8-10
  • Have heavy clay soil that stays wet
  • Garden in deep shade
  • Prefer plants that stay green and lush with regular watering

The Bottom Line

Hartweg’s sundrops represents everything great about native plant gardening – it’s beautiful, supports local ecosystems, requires minimal resources, and thrives in conditions where other plants struggle. For Texas gardeners especially, this little gem offers months of sunny yellow blooms with almost no effort required.

Whether you’re creating a water-wise landscape, establishing a pollinator garden, or simply want something reliable and cheerful for that challenging sunny spot, Hartweg’s sundrops deserves serious consideration. After all, any plant that can look this good while asking for so little has definitely earned its place in the garden!

Hartweg’s Sundrops

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Myrtales

Family

Onagraceae Juss. - Evening Primrose family

Genus

Calylophus Spach - sundrops

Species

Calylophus hartwegii (Benth.) P.H. Raven - Hartweg's sundrops

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