Resilient to both high summer heat and drought, glossy abelia (Abelia x grandiflora) bears tubular flowers that attract butterflies. This hybrid, broadleaf evergreen shrub originated in Italy in the mid-19th century. This spreading, mounding shrub reaches a mature height of 3 to 7 feet with equal spread. Grow it in USDA Hardiness Zones 6 through 9.
Glossy abelia tolerates up to 10 hours of full sun to part shade, with a minimum requirement of three to four hours of daily sun. In hot summer climates, some shading from the most intense midday and afternoon sun keeps foliage and flowers looking most attractive, especially if soil occasionally dries slightly. Densest growth and widespread flowering occurs with at least 5 hours of direct sun from spring to early fall.
Prospering in acidic soils (those with a pH reading below 7.0), this shrub grows best if the soil drains well, never remaining flooded after rain. Clay, loam or sandy soils that are rich in organic matter, shaded with a 3- or 4-inch layer of organic mulch and remain evenly and consistently moist provide excellent growing conditions. Once established in the garden after two or three years, the roots of glossy abelia manage to sustain healthy foliage even in drought conditions during summer's heat.
Provide 3/4 to 1 inch of water to the plant weekly from spring to late summer. Natural rainfall or irrigation water suffices. Water less outside the growing season; often natural rainfall from mid-autumn to early spring provides ample moisture. Although quite drought-tolerant, irregular and deep weekly waterings during a prolonged drought help assimilate the plant to drier conditions. In these conditions, provide the plant with 2 inches of water every three weeks to sustain it.
The hybrid glossy abelia needs a period of dormancy in winter marked by reduced temperatures. Nighttime winter low temperatures must drop below 30 to 40 degrees F consistently for healthy growth and flowering once the growing season returns each spring. Prolonged cold with temperatures that drop below 0 degrees F causes the usually evergreen leaves to drop off. Temperatures under -15 to -10 degrees desiccate twigs and kill roots.