How to Grow Japanese Holly Convexa

Japanese Holly Convexa

Ilex crenata 'Convexa'

shrub

Japanese Holly Convexa is a compact, evergreen shrub with small, convex, glossy dark green leaves that create a dense, mounding habit. This cultivar is highly valued in ornamental landscaping for its fine texture, year-round foliage, and ability to tolerate pruning and shaping. It produces small white flowers in spring and bright red berries on female plants when pollinated by male cultivars.

Growing Conditions

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Sun: Partial shade to full sun; prefers 4-6 hours of sunlight daily; afternoon shade in hotter climates (zones 8-9)

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Water: Keep soil consistently moist but not waterlogged. Water deeply 1-2 times per week during growing season; reduce in winter. Mulch to retain moisture and keep roots cool.

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Spacing: 24-36 inches

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Days to maturity: 3-5 years to reach mature landscape size (2-4 feet tall and wide)

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Planting depth: Plant at same depth as root ball; top of root ball should be level with or slightly above soil surface

Soil

Type: Well-draining, slightly acidic loamy soil

pH: 5.5-6.5

Amendments:

Peat moss Compost Perlite for drainage Mulch (2-3 inches)

Growing Zones

Find your zone →

Thrives in zones 5-9, with best performance in zones 6-8

5a 5b 6a 6b 7a 7b 8a 8b 9a

Growth Stages

Establishment

6-12 months

Young plant focuses on root development; limited new shoot growth in first year after planting

Water regularly to keep soil moist; apply mulch; avoid pruning in first year; provide afternoon shade in hot climates

Vegetative Growth

1-3 years

Plant develops dense foliage with small, convex leaves; forms rounded mound; vigorous branching

Maintain consistent moisture; fertilize in early spring with balanced, slow-release fertilizer; light pruning to shape; remove any dead branches

Flowering

3-4 weeks (late April to May)

Small, fragrant white flowers appear in clusters along stems in late spring; female plants only produce flowers if male pollinator nearby

No special care needed; flowers are self-sufficient; do not prune during flowering if berries desired

Berry Development

4-6 months (June through winter)

Small bright red berries develop on female plants after successful pollination; berries persist through winter

Ensure male pollinator plant nearby for female flowers; do not over-fertilize with nitrogen as it reduces berry production

Dormancy & Maintenance

3-4 months (November through February)

Plant slows growth in winter; foliage remains evergreen and vibrant; berries remain decorative

Reduce watering in winter but do not allow soil to dry completely; prune in late winter (February-March) before new growth; monitor for pests and diseases

Companion Planting

Plan your garden →

Plant with:

Boxwood Yew Wintercreeper Rhododendron Azalea Japanese Maple Hosta Hellebore Fern Euonymus

Avoid planting near:

Black walnut (produces juglone toxin) Salt spray areas (susceptible to salt damage) Poorly drained areas with standing water

Common Pests

Spray with insecticidal soap or neem oil; increase humidity; prune affected branches; monitor during hot, dry periods
Prune infested branches; apply horticultural oil spray in early spring before new growth; insecticidal soap for crawlers
Remove affected leaves; spray with neem oil; maintain plant vigor through proper watering; parasitic wasps help naturally
Remove affected leaves promptly; improve air circulation through pruning; avoid overhead watering; apply fungicide if severe
Ensure excellent drainage; do not overwater; remove affected plant if severely infected; amend soil with perlite or sand

Uses

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Topiary & Hedge Shaping

Ornamental

Japanese Holly Convexa's fine texture and compact growth habit make it ideal for creating topiaries, hedges, and formal shaped landscapes. Its ability to tolerate repeated pruning without damage makes it a favorite for intricate landscape designs. [source]

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Foundation Plantings

Landscape

The mounding form and evergreen foliage provide year-round structure and color in foundation plantings, shrub borders, and container gardens. Its compact size suits small to medium spaces. [source]

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Wildlife Food Source

Wildlife

The red berries provide important winter food for songbirds and wildlife, while the dense foliage offers shelter and nesting habitat. Female plants with berries are especially valuable for bird populations. [source]

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Holiday Decorations

Craft

Branches with berries are used in holiday arrangements, wreaths, and centerpieces for festive seasonal decor. The glossy foliage and bright berries add visual interest to flower arrangements. [source]

Harvest Tips

Berries are ornamental and persist through winter; harvest branches for holiday decorations in fall or winter. Cut branches with sharp pruners; female plants produce berries only with nearby male pollinator. Prune in late winter (February-March) before new growth; can be selectively pruned throughout growing season to maintain shape.

Fun Facts

🌱 The name 'Convexa' refers to the distinctive convex (outward-curving) shape of the leaves, which is unique among many Ilex crenata cultivars and gives the plant its characteristic refined appearance.
🌱 Japanese Holly Convexa is dioecious, meaning plants are either male or female; only females produce berries, and they require nearby male plants for pollination—a single male can pollinate multiple females within 50+ feet.
🌱 This shrub has been used in Japanese gardens and bonsai cultivation for centuries and remains one of the most popular evergreen shrubs for ornamental gardening in temperate climates worldwide.

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