How to Grow Japanese Holly Convexa
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Japanese Holly Convexa
Ilex crenata 'Convexa'
shrubJapanese 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.
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Example Japanese Holly Convexa timeline · Pittsburgh, PA (Zone 6b)
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Plant Japanese Holly Convexa
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Japanese Holly Convexa
Late summer into fallBefore the first fall frost (≈ Nov 8)
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 5-9, with best performance in zones 6-8
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Get my Japanese Holly Convexa timeline →Growth Stages
Establishment
6-12 monthsYoung 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 yearsPlant 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:
Avoid planting near:
Common Pests
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Spray with insecticidal soap or neem oil; increase humidity; prune affected branches; monitor during hot, dry periods
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Prune infested branches; apply horticultural oil spray in early spring before new growth; insecticidal soap for crawlers
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Remove affected leaves; spray with neem oil; maintain plant vigor through proper watering; parasitic wasps help naturally
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Remove affected leaves promptly; improve air circulation through pruning; avoid overhead watering; apply fungicide if severe
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Ensure excellent drainage; do not overwater; remove affected plant if severely infected; amend soil with perlite or sand
Uses
Topiary & Hedge Shaping
OrnamentalJapanese 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]
Foundation Plantings
LandscapeThe 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]
Wildlife Food Source
WildlifeThe 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]
Holiday Decorations
CraftBranches 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.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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