Geoffrey Njue, UMass Extension Sustainable Landscapes Specialist
Ilex x meserveae, Blue holly or Meserve holly
Blue holly, or Meserve holly, is an evergreen hybrid holly of Ilex aquifolium x Ilex rugosa. They are shrubby in habit and have alternate, leathery, glossy dark green almost blue-green leaves with spiny margins. Plants typically grow to 8-10 feet tall, but occasionally to as much as 15 feet tall. They bloom in May with greenish-white flowers in small clusters which produce showy bright red berries on female plants in fall. The berries often persist until spring. Flowers, although not ornamental, attract bees and the fruits are attractive to birds. Like other hollies, Meserve holly plants are dioecious (separate male and female plants). One male pollinator is needed for every 3 to 5 female plants for berry production. Blue hollies are winter hardy to USDA Zones 5 - 8.
Plants are best sited in locations protected from cold winter winds. Blue holly grow best in slightly acidic, moist, well-drained soils in full sun to part shade. Part afternoon shade is best in hot summers. Blue hollies can be used in mass plantings, hedge or borders, foundations and as specimen plants. Potential problems include interveinal chlorosis (yellowing of leaves in high pH soils), holly leaf miner, spider mites, whitefly and scale, leaf scorch, tar spot, and phytophthora root rot.
Cultivars include:
‘Blue Princess' (female) – 15 feet tall, dark blue green foliage and an abundance of red fruit
‘Blue Prince' (male) – 8 - 12 feet tall, and very dense, with dark green foliage, very cold hardy.
‘Blue Girl' (female) – 8 - 10 feet tall, dark green foliage and bright red fruit.
‘Blue Boy' (male) – 10-15 feet tall; dark green leaves.