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Daphne x transatlantica 'Summer Ice'
Summer Ice hybrid daphne
Hybrid of garden origin; the cross was made between Daphne caucasica (native to the Caucasus Mountains of eastern Europe and western Asia) and Daphne collina (native to the Mediterranean region of southern Europe)
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At a Glance
TypeShrub
HabitMounding
FoliageSemi-evergreen
Height2-3 feet (0.6-0.9 m)
Width2-4 feet (0.6-1.2 m)
Maturity6 years
Key Features
Maintenancemoderate
Overview
Daphne × transatlantica 'Summer Ice' is a compact mounding semi-evergreen hybrid shrub in the family Thymelaeaceae growing 2–3 feet (0.6–0.9 m) tall and 2–4 feet (0.6–1.2 m) wide. The hybrid is a cross between Daphne caucasica (native to the Caucasus Mountains of eastern Europe and western Asia) and Daphne collina (native to the Mediterranean region of southern Europe), and the hybrid epithet transatlantica was coined to recognize the transatlantic breeding work that produced the hybrid. 'Summer Ice' is the variegated form of this hybrid cross, and the cream-white-margined foliage is the main vegetative character that separates the cultivar from the plain-green 'Eternal Fragrance' (the original non-variegated selection of D. × transatlantica). Leaves are narrowly oval-elliptic, 1–2 inches (2.5–5 cm) long, with dark green centers and broad creamy-white margins, and the variegation is stable — the cultivar does not revert to plain green growth as some variegated shrubs do — which is one of the reasons for its commercial success. White to faintly blushed-pink tubular 4-lobed flowers 0.3–0.4 inch (8–10 mm) long open in terminal clusters of 5–15 at the branch tips continuously from April through October across a 26-week bloom period — this continuous spring-through-fall flowering is a long bloom window for a hardy shrub, and the flowers carry an intensely sweet fragrance that is detectable at several feet from the plant. Limitation: all parts of the plant — bark, leaves, flowers, and berries — contain daphnin (a coumarin glycoside) and mezerein (a diterpene ester), which are toxic to humans, cats, and dogs if ingested and produce severe gastrointestinal irritation, oral burning, and (at higher ingested quantities) cardiac and neurological effects. The sap can also cause contact dermatitis on sensitive skin when the foliage or stems are cut. Positions near areas where children play or pets frequent are unsuitable because of this toxicity profile. The cultivar is not drought-tolerant and calls for consistent moisture through the growing season, and well-drained soil is a cultural requirement because the species develops root rot in waterlogged conditions. Native range: hybrid of garden origin. Deer-resistant because of the coumarin and diterpene content.
Native Range
Hybrid of garden origin — the cross was made between Daphne caucasica (native to the Caucasus Mountains of eastern Europe and western Asia, where it grows in mountain forest understory and rocky slopes) and Daphne collina (native to the Mediterranean region of southern Europe). 'Summer Ice' is the variegated selection from the D. × transatlantica hybrid cross and was introduced to commercial cultivation in the early 2000s through the North American Daphne breeding program.Suggested Uses
Used as a fragrant specimen shrub near doorways, patios, walkways, and seating areas where the 26-week bloom fragrance is accessible, in mixed shrub borders, and in containers of at least 5 gallons (19 L) at 2–4 foot (0.6–1.2 m) spacing between plants in USDA zones 5 through 9. The continuous spring-through-fall bloom, the intense sweet fragrance, and the year-round variegated foliage carry the cultivar through four seasons of ornamental interest in compact positions where a small fragrant shrub fits better than a larger specimen. Positions near areas where children play or pets frequent are unsuitable because of the daphnin and mezerein toxicity of all plant parts, and waterlogged positions and heavy clay soils without drainage amendment are unsuitable because of the root rot sensitivity. The plain-green D. × transatlantica 'Eternal Fragrance' is the alternative cultivar where variegated foliage is not wanted.How to Identify
Appearance
Size & Dimensions
Height2' - 3'
Width/Spread2' - 4'
Reaches mature size in approximately 6 years
Bloom Information
White to faintly blushed-pink tubular 4-lobed flowers 0.3–0.4 inch (8–10 mm) long open in terminal clusters of 5–15 at the branch tips continuously from April through October across a 26-week bloom period. The continuous spring-through-fall flowering is a long bloom window for a hardy shrub, and the flowers carry an intensely sweet fragrance that is detectable at several feet from the plant. Honeybees work the flowers for nectar across the full bloom period.Detailed Descriptions
Flower Description
white to faintly blushed-pink tubular 4-lobed flowers 0.3-0.4 inch (8-10 mm) long carried in terminal clusters of 5-15 at the branch tips; strongly fragrant with an intensely sweet scent that is detectable at several feet from the shrub; the flowers open continuously from April through October across the full growing seasonFoliage Description
dark green centers with broad creamy-white margins; narrowly oval-elliptic leaves 1-2 inches (2.5-5 cm) long arranged alternately along the stems; the cream-white variegation is stable and the cultivar does not revert to plain green as some variegated shrubs do; semi-evergreen — retained in mild winters in zones 7 through 9 and partially shed during hard winters in zones 5 and 6Growing Conditions
Sun Requirements
Requires 3-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Site in part sun to partial shade with 3–6 hours of direct sun per day, typically in morning-sun positions with afternoon shade. Well-drained loam or sandy soil with a pH of 6.0–7.5 holds the root system through all seasons — the cultivar is not drought-tolerant and calls for consistent moisture through the growing season, and waterlogged conditions produce root rot. All parts of the plant contain daphnin (a coumarin glycoside) and mezerein (a diterpene ester) and are toxic to humans, cats, and dogs if ingested, producing severe gastrointestinal irritation, oral burning, and (at higher ingested quantities) cardiac and neurological effects; the sap can also cause contact dermatitis on sensitive skin when the foliage or stems are cut. Light pruning after the spring bloom flush (June) is done to shape the plant if needed — the natural compact mounding form is self-maintaining and does not call for heavy pruning, and leather gloves are warranted during any pruning operation because of the sap toxicity. Deer-resistant. Hardy in USDA zones 5–9.Pruning
Light pruning after the spring bloom flush (June) is done to shape the plant if needed, and the natural compact mounding form is self-maintaining and does not call for heavy pruning. Dead or damaged growth is removed at any time of year. Leather gloves are warranted during any pruning operation because the cut stems release sap that contains daphnin and mezerein and can cause contact dermatitis on sensitive skin. Hard renovation pruning is poorly tolerated by the genus and is avoided because Daphne species do not reliably regenerate from old bare wood cuts.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
late spring
Maintenance Level
moderateContainer Growing
✓ Suitable for container growing
Minimum container size: 5 gallons