🌸 Cornus × elwinortonii ‘KN4-43’ STARLIGHT®

🔎 Identification

Scientific name: Cornus × elwinortonii ‘KN4-43’.

Trade name: Starlight® Dogwood.

Synonyms: Cornus kousa × Cornus nuttallii ‘KN4-43’, Cornus ‘KN4-43’.

Family: Cornaceae (dogwood family).

Common names: Starlight hybrid dogwood, Starlight dogwood.

Parent species' origins: Cornus kousa (Japan, Korea and China) and Cornus nuttallii (Pacific coast of North America).

Cultivar origin: American horticultural selection developed by Dr Elwin Orton at Rutgers University, New Jersey.

Type: Deciduous ornamental tree.

Special feature: A remarkable hybrid with extremely abundant flowering and large creamy-white bracts reaching about 10 to 13 cm across. It combines Cornus nuttallii's upright, vigorous silhouette with Cornus kousa's good disease resistance. Part of the Jersey Star™ horticultural series developed at Rutgers.

🌿 Botanical description

Habit: Upright, oval to broadly pyramidal when young, gradually becoming more rounded and spreading.

Height: About 7.5 to 9 m, approaching 10 m at maturity.

Spread: About 6 to 7 m, sometimes more depending on conditions.

Growth: Moderate to fast. Particularly vigorous in favourable growing conditions.

Trunk: Generally straight, with relatively low branching on young trees.

Branches: Numerous, upright to spreading, forming a dense, well-structured crown.

Leaves:

• Simple and opposite.

• Oval to elliptical.

• Pointed tips.

• Entire margins, sometimes slightly wavy.

• Dark to deep green in summer.

• Glossy surface.

• Relatively firm texture.

• Clearly visible veins.

• Red to reddish purple in fall.

Special feature: Dense dark green foliage provides a particularly appealing backdrop to white blossoms. Its naturally upright, oval habit creates an elegant, relatively regular silhouette.

🌸 Flowering

Period: May to June, depending on climate and region.

Flowering: Generally about one week before Venus® Dogwood.

Flowers:

• Small greenish true flowers grouped in the centre of a flower head.

• Surrounded by four large floral bracts.

• Bracts oval to slightly pointed.

• The whole flower head can measure about 10 to 13 cm across.

• Generally creamy white with slight pale green shades initially.

• Become whiter at maturity.

• May develop a slight pink tinge with age.

Colour: Creamy white to slightly greenish white.

Duration: Several weeks in favourable weather.

Abundance: Particularly high. Flowers can almost completely cover the branches, making the tree appear covered in large white blooms.

Special feature: Starlight® flowers extremely generously and its bracts are relatively firm. It inherits spectacular flowering and large bracts from Cornus nuttallii, while benefiting from improved disease resistance through Cornus kousa.

It also flowers about a week before Venus®, creating an appealing succession of blooms when the two cultivars are planted together.

🍓 Fruit

Type: Spherical fleshy fruit resembling small raspberries.

Size: About 1.5 to 2 cm across.

Colour: Red to orange-red when ripe.

Ripening period: August to September, sometimes into October, depending on the climate.

Features:

• Fruit grouped into small spherical masses.

• Bumpy, slightly granular surface.

• Resembles Cornus kousa fruit.

• Production varies with pollination conditions.

• Some fruit is parthenocarpic, meaning it develops without seeds.

• Appreciated by birds.

Edibility: Cornus kousa fruit is edible. However, Starlight® fruit's specific food characteristics are less well documented. It is best not considered a fruit-tree cultivar.

Uses: Mainly ornamental and ecological.

Special feature: Unlike some nearly sterile hybrids, Starlight® can produce appreciable quantities of ornamental red fruit. Seed production generally remains limited because of low reproductive compatibility.

🍂 Fall colour

Period: September to October, depending on the climate.

Colours:

• Scarlet red.

• Orange-red.

• Dark red.

• Reddish purple.

Special feature: Dark green foliage gradually turns a particularly appealing red. Orange-red fruit may also be present, creating ornamental contrast with fall foliage.

Colour is generally more intense with good light exposure.

🌱 Growing conditions

Exposure: Sun to partial shade.

Soil: Rich, humus-rich, fertile and well drained.

Texture: Prefers loamy soil rich in organic matter. Tolerates various soil types with adequate drainage.

pH: Slightly acidic to neutral.

Moisture: Prefers cool, consistently moist soil.

Watering: Regular during the first few years and prolonged droughts.

Planting: Spring or fall.

Spacing: Allow about 6 to 7 m for natural crown development.

Location: Choose a bright spot, relatively sheltered from drying winds.

Special feature: Once well established, Starlight® tolerates drought well compared with many other dogwoods. It nevertheless prefers moist, organic-rich soil for vigorous growth and abundant flowering. Avoid constantly waterlogged ground.

❄️ Hardiness

Zone: 6a according to Rutgers University references. Some horticultural references also indicate zones 6 to 8, while other trials report tolerance down to zone 5.

Approximate minimum temperature: About -23 to -26 °C, depending on exposure, microclimate and establishment.

Winter resistance:

• Good hardiness for a hybrid dogwood.

• Suited to cool temperate regions.

• Young trees benefit from protection during their first winters.

• Drying winter winds can damage young shoots.

• Late frosts can affect flower buds and bracts.

• A protected location improves the chances of success in cold regions.

Special feature: Rutgers recognizes Starlight® for good winter resistance. For Quebec, I would nevertheless favour areas with a suitable microclimate, especially in zone 5. Consider hardiness cautiously where temperatures regularly fall below -25 °C.

✂️ Care

Pruning: Generally unnecessary. Retain its natural upright, oval habit.

Pruning period: After flowering or in late winter to remove dead, broken or poorly positioned branches.

Fertilizing: Well-rotted compost in spring, if needed.

Mulching: Recommended to retain soil moisture and protect shallow roots.

Watering: Monitor especially during the first few years and prolonged droughts.

Propagation: Mainly by grafting or cuttings, depending on horticultural methods. Grafting faithfully preserves cultivar characteristics.

Transplanting: Prefer young trees and avoid significant root disturbance.

Diseases and pests:

• Dogwood anthracnose.

• Powdery mildew.

• Leaf spots.

• Scale insects.

• Root rot in waterlogged soil.

• Water stress during prolonged drought.

Special feature: Starlight® has high resistance to dogwood anthracnose and powdery mildew. Rutgers even reports no major insect or disease problems on the original hybrid tree over nearly 30 years. This is a major advantage over some more sensitive ornamental dogwoods.

🦋 Ecological value

• Small central flowers may attract pollinating insects.

• Red fruit provides food for birds.

• Dense foliage shelters small wildlife.

• Abundant flowering adds to the garden's floral diversity.

• Can be included in natural or ornamental gardens.

• Offers ecological value across several seasons.

Special feature: Abundant flowering is its main attraction for pollinating insects. Fall fruit also provides a useful food resource for birds, although production varies with pollination conditions.

✅ Highlights

• Extremely abundant flowering.

• Large creamy-white bracts.

• Bracts can reach about 10 to 13 cm across.

• Generally flowers one week before Venus®.

• Glossy dark green foliage.

• Beautiful red to purple fall colours.

• Ornamental red fruit.

• Upright, oval habit.

• Relatively vigorous growth.

• Good anthracnose resistance.

• Excellent powdery mildew resistance.

• Good drought tolerance once established.

• Low maintenance.

• Ornamental interest across several seasons.

• Excellent specimen tree for large gardens.

❌ Points to consider

• Needs plenty of space at maturity.

• Can reach nearly 10 m tall.

• Less hardy than some Cornus kousa cultivars.

• Prefers slightly acidic soil.

• Avoid constantly waterlogged ground.

• Prolonged drought can affect foliage quality.

• Young trees need special attention during their first winters.

• Late frosts can damage flowering.

• Disease resistance does not mean complete immunity.

• May be difficult to find in some nurseries.

🌳 Distinctive feature: Starlight® is a particularly impressive hybrid dogwood for spectacular flowering and a naturally upright habit. In spring, branches carry masses of large creamy-white bracts reaching about 13 cm across. Flowering is so abundant that it can almost completely hide the foliage. It also flowers about a week before Venus®, extending the flowering season when both varieties are grown together. Dark green foliage, red fall colour and remarkable disease resistance make it especially appealing for landscapes.