Skip to content

Plant Finder


Hartweg's Sundrops

Calylophus hartwegii

Add To My Wish List

Hartweg's Sundrops (Calylophus hartwegii) at Roger's Gardens

Hartweg's Sundrops in bloom

Hartweg's Sundrops in bloom

(Photo courtesy of NetPS Plant Finder)

Hartweg's Sundrops (Calylophus hartwegii) at Roger's Gardens

Hartweg's Sundrops flowers

Hartweg's Sundrops flowers

(Photo courtesy of NetPS Plant Finder)

Height:  18 inches

Spread:  3 feet

Sunlight:  full sun  partial shade 

Hardiness Zone:  8b


Blooms profusely in spring with masses of bright yellow cup shaped blooms that open in the evening and close the following afternoon; drought tolerant once established; an excellent choice for rock gardens; prefers afternoon shade

Ornamental Features

Hartweg's Sundrops has masses of beautiful lightly-scented yellow cup-shaped flowers at the ends of the stems from mid spring to late summer, which are most effective when planted in groupings. Its small narrow leaves remain green in color throughout the year.

Landscape Attributes

Hartweg's Sundrops is an herbaceous evergreen perennial with a ground-hugging habit of growth. It brings an extremely fine and delicate texture to the garden composition and should be used to full effect.

This is a relatively low maintenance plant, and is best cleaned up in early spring before it resumes active growth for the season. It is a good choice for attracting bees, butterflies and hummingbirds to your yard. It has no significant negative characteristics.

Hartweg's Sundrops is recommended for the following landscape applications;

  • Mass Planting
  • Rock/Alpine Gardens
  • General Garden Use
  • Container Planting

Planting & Growing

Hartweg's Sundrops will grow to be about 18 inches tall at maturity, with a spread of 3 feet. Its foliage tends to remain dense right to the ground, not requiring facer plants in front. It grows at a fast rate, and under ideal conditions can be expected to live for approximately 10 years. As an evegreen perennial, this plant will typically keep its form and foliage year-round.

This plant does best in full sun to partial shade. It is very adaptable to both dry and moist growing conditions, but will not tolerate any standing water. It is considered to be drought-tolerant, and thus makes an ideal choice for a low-water garden or xeriscape application. It is particular about its soil conditions, with a strong preference for clay, alkaline soils, and is able to handle environmental salt. It is somewhat tolerant of urban pollution. This species is native to parts of North America.

Hartweg's Sundrops is a fine choice for the garden, but it is also a good selection for planting in outdoor pots and containers. Because of its spreading habit of growth, it is ideally suited for use as a 'spiller' in the 'spiller-thriller-filler' container combination; plant it near the edges where it can spill gracefully over the pot. Note that when growing plants in outdoor containers and baskets, they may require more frequent waterings than they would in the yard or garden.

Hardiness Zone Plant Height Minimum Sunlight Soil pH Preference
Massing  Rock  Garden  Container 
Flowers  Texture  Attracts Wildlife 
Ornamental Features