Dwarf Japanese holly, (Ilex crenata) is one of the finest-textured shrubs available (Figure 1). These durable hollies are very flexible as landscape plants as they grow well in full sun to light shade. They lend themselves to a variety of soil types and are available at most nurseries and garden centers. The dark green foliage lends a rich air to any landscape, particularly when combined with lighter green turf and shrubs. Plant on 3- to 4-foot-centers to establish a row or mass planting.
Scientific name: Ilex crenata 'Helleri'
Pronunciation: EYE-lecks kren-NAY-tuh
Common name(s): 'Helleri' holly
Plant type: shrub
USDA hardiness zones: 5B through 8A (Figure 2)
Planting month for zone 7: year round
Planting month for zone 8: year round
Origin: not native to North America
Uses: foundation; mass planting; container or above-ground planter; superior hedge; border
Availablity: generally available in many areas within its hardiness range
Height: 3 to 6 feet
Spread: 5 to 8 feet
Plant habit: round
Plant density: dense
Growth rate: slow
Leaf arrangement: alternate
Leaf type: simple
Leaf margin: serrulate
Leaf shape: obovate
Leaf venation: pinnate
Leaf type and persistence: evergreen
Leaf blade length: less than 2 inches
Leaf color: green
Fall color: no fall color change
Fall characteristic: not showy
Flower color: white
Flower characteristic: spring flowering
Fruit shape: round
Fruit length: less than .5 inch
Fruit cover: fleshy
Fruit color: unknown
Fruit characteristic: rarely fruits
Trunk and Branches
Trunk/bark/branches: not particularly showy; typically multi-trunked or clumping stems
Current year stem/twig color: green
Current year stem/twig thickness: thin
Light requirement: plant grows in part shade/part sun
Soil tolerances: slightly alkaline; clay; sand; acidic; loam
Drought tolerance: high
Soil salt tolerances: unknown
Plant spacing: 36 to 60 inches
Roots: usually not a problem
Winter interest: no special winter interest
Outstanding plant: not particularly outstanding
Invasive potential: not known to be invasive
Pest resistance: long-term health usually not affected by pests
Use and Management
The dwarf Japanese hollies are best used in mass groups as low shrubs, low hedges, or tall groundcovers. The compact habit of growth, slow growth rate, and small leaves make these ideal plants for use as clipped, formal hedges. Adjacent plants will often grow together looking like a row or group of green mounds. Eventually, the crowns grow completely together forming a sea of green.
Cultivars: 'Convexa' grows to about eight feet in a vase or rounded form and has cupped, glossy leaves; 'Compacta' has a compact growth habit and grows to about five feet tall; 'Helleri' has a slight grayish cast to the foliage which sets it apart from other Japanese hollies; 'Northern Beauty'—improved cold tolerance, reaches a height and spread of three feet; 'Rotundifolia'—dense habit, large size, to 12 feet.
Propagation is by cuttings.
Pests and Diseases
Pest problems are many, including scale, spider mites, spittle bugs, and nematodes, but these are often of minor consequence.
No diseases are of major concern.