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Diadem Sweet William

Dianthus barbatus 'Diadem'

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Diadem Sweet William (Dianthus barbatus 'Diadem') at Squak Mountain Nursery

Dianthus barbatus 'Diadem' flowers

Dianthus barbatus 'Diadem' flowers

(Photo courtesy of NetPS Plant Finder)

Plant Height: 15 inches

Flower Height: 20 inches

Spread: 12 inches

Sunlight:  full sun 

Hardiness Zone: 3

Other Names: Perennial Sweet William


Deliciously clove-scented, velvety frilly blood-red flowers with white eyes and edges; optimal site has full sun with ample moisture; amend clay soils for best growth; seeds freely but divide for truest color

Ornamental Features:

Diadem Sweet William is blanketed in stunning fragrant crimson flat-top frilly flowers with white eyes and white edges at the ends of the stems from late spring to early summer. The flowers are excellent for cutting. It's tomentose pointy leaves remain dark green in color throughout the season. The fruit is not ornamentally significant.

Landscape Attributes:

Diadem Sweet William is an herbaceous perennial with an upright spreading habit of growth. Its relatively fine texture sets it apart from other garden plants with less refined foliage.

This perennial will require occasional maintenance and upkeep, and should only be pruned after flowering to avoid removing any of the current season's flowers. It is a good choice for attracting bees and butterflies to your yard, but is not particularly attractive to deer who tend to leave it alone in favor of tastier treats. Gardeners should be aware of the following characteristic(s) that may warrant special consideration;

  • Self-Seeding

Diadem Sweet William is recommended for the following landscape applications;

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

Plant Characteristics:

Diadem Sweet William will grow to be about 15 inches tall at maturity extending to 20 inches tall with the flowers, with a spread of 12 inches. Its foliage tends to remain dense right to the ground, not requiring facer plants in front. It grows at a medium rate, and tends to be biennial, meaning that it puts on vegetative growth the first year, flowers the second, and then dies. However, this species tends to self-seed and will thereby endure for years in the garden if allowed.

This perennial should only be grown in full sunlight. It prefers to grow in average to moist conditions, and shouldn't be allowed to dry out. It is not particular as to soil type or pH. It is highly tolerant of urban pollution and will even thrive in inner city environments. This plant can be propagated by division.

This is a selected variety of a species not originally from North America.

Hardiness Zone Plant Height Minimum Sunlight
Massing Rock Edging Garden Container
Flowers Attracts Wildlife
Ornamental Features