Holly is almost always associated with Christmas with its spiky green leaves and red berries, but not all holly trees are alike. There are over 400 varieties of holly, some with yellow, red or even black berries and some with bright green spiky leaves or dense, dark green foliage. Dwarf varieties of holly work well for growing in planters, especially since they are low-maintenance and somewhat slow-growing, meaning that transplanting is rarely needed. A few basic steps will get you off to the best start for planting your dwarf holly tree in a planter.
Choose a 15- to 20-gallon planter that has drainage holes in the bottom to allow good drainage for your tree. Add a 1- to 2-inch layer of crushed rock or pebbles to the bottom of the planter to aid with water drainage and help keep the soil from washing out of the drainage holes.
Use an acidic potting soil with a pH of 4.5 to 7. If the soil is too alkaline the leaves of your holly tree will turn yellow. Fill one-third of the planter with your potting soil.
Set your dwarf holly tree into the planter and, holding up straight, fill in the planter with rest of your soil. Pack it down firmly around the tree. Packing the soil firmly as you fill in with soil is essential for eliminating air pockets around the roots.
Water your tree well after planting by letting water trickle from a garden hose for about 10 to 20 minutes or until the water starts coming out of the bottom of the planter. It's important to keep the soil moist but not let it get soggy, which can cause root rot. Holly trees do not tolerate drought so never let the soil dry out between watering. For most trees, watering every other day is sufficient.
Fertilize your dwarf holly tree one month from the time you planted it to allow the roots to get established. Apply a balanced slow-release fertilizer and water in well after applying. Feeding your tree one time per year is all it needs.
Set your potted dwarf holly tree in a sunny location during the day with some partial shade during the late afternoon. Potted holly trees can be set on a patio, on either side of a front door or anywhere in your garden.