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Sweet William
Dianthus barbatus
Also comes in red, white and purple.
Sweet William blooms from May through July.
This entry comes from our curated library and has not yet been independently checked against outside sources. Curated is not unreliable: a standing audit keeps every entry internally consistent, and the source-by-source check is working through the whole library in the open.
Growing Sweet William
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–9. Expect it to reach about 1.3 ft tall and 12 in wide at maturity, in roughly 2 years.
When to plant Sweet William
Plant Sweet William in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. For the middle of its hardy zones 3 to 9 range, spring means March to May and fall means August or September. Once settled, it blooms from May to July.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 6 in March.
Good to know about Sweet William
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Mildly toxic to dogs and cats: an irritant causes mild stomach upset if eaten, and the foliage's saponins can give sensitive skin brief contact dermatitis. per ASPCA and NC State
Worth knowing
Often sold as a perennial, but it usually lives like a biennial: a leafy rosette the first year, flowers the second, then it fades. Resow to keep it going. per NC State and Clemson
Rabbit resistance is uncertain
NC State's species page calls it rabbit resistant, but its genus page says rabbits will browse it. Deer resistance is solid; do not count on rabbit protection. per NC State
Wet soil is the killer
Its top failure mode is crown and root rot in soggy ground, and the same wet conditions bring on rust. Sharp drainage and spacing for airflow prevent both. per NC State and UC IPM
Fragrant but deer resistant
The same pungent, sharp-tasting foliage that deters deer carries the fragrance and nectar that draw bees and butterflies. Its scent works for you two ways. per NC State
The name means bearded
The species name 'barbatus' means bearded, for the fringed, whiskery look of the frilled petals and the bracts beneath each flower cluster. per NC State
A cottage cutting-garden staple
The long-stemmed, flat-topped flower clusters are a cottage-garden cutting staple; cut them from a dedicated patch as the blooms open. per NC State
What pairs well with Sweet William
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Perennial Sunflower
Shares full sun and moderate water; blooms in late summer as this one finishes; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Goldenrod
Shares full sun and low to moderate water; blooms in late summer as this one finishes; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Ironweed
Shares full sun and moderate water; blooms in late summer as this one finishes; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Pampas Grass
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; stands well above at 8.2 ft, a canopy to plant beneath.
Switchgrass
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; taller at 4.9 ft, for the layer behind it.
Fountain Grass
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; taller at 3.3 ft, for the layer behind it.
Serviceberry
Takes full sun to part sun and moderate water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; its white flowers settle the red.
Hyacinth
Shares full sun and moderate water; blooms in early spring, before this one opens; lower at 10 in, for the front of the border; both offer pollinator forage, in different months.
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