In spaces where you cannot plant trees directly into the ground, like roof gardens, patios or courtyard gardens, you can grow trees in containers. This is the quickest way to create a well-established appearance, by adding height and structure to the design. Growing trees in large containers, like pots or tubs, will greatly extend their design potential.
You can use trees grown in large pots or tubes to frame a doorway that is surrounded by hard paving and nothing else can be planted around, or you can use these trees to flank wide steps. Any of these sittings are particularly appropriate for topiary. Topiary are trees or shrubs trained and pruned to attractive, boldly artificial shapes. Small trees grown in containers are valuable for bringing color, vitality and sculptural interest to a patio, terrace or balcony, places where they cannot be planted directly into the ground. Use specimens with colorful foliage or flowering trees to add more interest.
In colder areas you can grow in containers trees that are too tender to overwinter outside. Display them outdoors in summer and move them back to a frost-free place as cold weather approaches. To take more advantage of space you can plant annuals and tender plants at the base of the trees. These will add seasonal color and interest. Also you can plant ivy for a permanent ground cover.
Trees grown in containers are long-term features so you must consider using containers that are durable and attractive in the same time. You will find on the market a wide range of styles and materials, so is only up to you to choose the right ones that fit your design. Just make sure that the containers are frost-proof if you are going to use the as permanent features in areas subject to frost.
Always remember when planting large plants, like trees or shrubs in containers, that they will need an appropriate large container to hold enough soil for the vigorous roots. Also they will need much more care and attention than ground planted specimens as their growing medium is limited. Water them regularly and feed them as needed.