The common holly (Ilex aquifolium), also called the English holly, is a slow-growing evergreen tree that has shiny, dark green leaves and yellow, orange or red berries. The holly tree grows in a pyramid shape with dense, heavy foliage and branches. Growing to a mature height of 15 to 50 feet and width of 15 feet, the common holly enjoys moderate temperatures and humidity. The holly tree grows best in USDA hardiness zones 6 through 8, where minimum winter temperatures don't drop below minus 5 degrees Fahrenheit.
Plant your holly tree in rich, well-draining and slightly acidic soil. Select a planting site that receives partial sunlight and provides some shade in the hotter summer months. Plant your holly tree in early spring.
Dig a planting hole that is the same depth as and twice the width of the holly tree's root ball or nursery container. Loosen the soil and mix into the displaced dirt some organic compost, so that you have at least one part compost to two parts native soil.
Set the holly tree's root ball into the planting hole and back fill the hole with the amended soil. Plant the holly tree at the same depth as it was planted in the nursery container.
Water the soil around the holly tree thoroughly to saturate the soil down to and around the root area. Spread a 2- to 4-inch layer of bark mulch over the ground around the root zone to control weeds and retain soil moisture.
Water your holly tree once or twice per week to supplement rainfall during the spring and summer months. Water the tree to keep the soil around the roots moderately moistened at all times, wetting the soil to the depth of the root ball.
Feed your holly tree once each year in early spring with a slow-release fertilizer made for acid-loving broadleaf evergreen trees. Follow the dosage and application instructions on the label.
Prune your holly tree in early spring before any new growth emerges to maintain its shape and remove any dead, diseased or damaged growth. Trim the holly tree back to keep a streamlined, symmetrical form by clipping the branches back to the nearest crotch or healthy set of buds.