You will find trees offered in one of three ways;
Bare-rooted trees: Young bare-rooted trees one-to-three years old establish well, but are increasingly difficult to obtain compared with container-grown stock. Pre-ordered bare-rooted stock is usually available from about November and should arrive wrapped in polythene to prevent the fibrous roots drying out. The tree should have a well-developed root system spreading evenly in all directions. Do not buy trees with ‘hockey stick’ roots, where all the growth is on one side. Early planting will allow some root growth before temperatures rise in the spring.
Root-balled trees: Larger semi-mature trees and some evergreens, especially conifers, are available root-balled. This is where the root system has been held in place with fabric and, sometimes, wire mesh. Root-balled trees have usually been ‘undercut’ (root pruned) or transplanted several times to encourage the development of a fibrous root system. They often establish better than container-grown trees as they have been grown in soil in the open ground rather than commercial potting compost. Although these trees are relatively expensive, the fibrous root system remains more intact. Buy and plant root-balled trees when dormant, in autumn or early spring, following the same criteria as for bare-root and container-grown trees.
Containerised trees: With pot-grown trees it is vital to remove any excess compost from above the root collar (the point just below which the roots naturally start to grow). If the tree is planted to the original level of compost in the pot, as usually recommended, it could already be too deep. Secondary adventitious roots are common in pot-grown trees, originating from the buried part of the trunk. These should be pruned off close to their point of origin.
Thoroughly tease out the roots. Do not be afraid to open up a congested root ball using a sharpened piece of cane to disentangle the roots if necessary. If this is not done, the roots will frequently fail to grow out into the soil and the tree will fail to establish. Any damaged roots should also be trimmed back.
How to select and buy specimen trees
Selecting and buying specimen trees is not always straightforward. The following points need to be taken into consideration:
Height and spread: This is probably the most important factor. Make sure you select a tree which has an ultimate height suitable for your garden. Even small ornamental trees may, over 20 years, reach a height of 6-7m (18-21ft) or more.
Season of interest: Consider when you want your tree to look good, thinking about flowering time, foliage, fruit and bark. If you only have room for one tree, look for one with more than one season of interest such as fruit or autumn colour following on from flowers.
Condition: As you will be spending a lot of money on one tree, check that it is in good condition. There should be a well-balanced branch system and no wounds or damage to the bark, or dead or distorted foliage.
Access: Check the practicality of bringing a large tree into the garden; confirm access and proximity to drainage channels and services (e.g. drains and cable lines).
Site preparation: Plants will not grow where soil contains too little air, insufficient nutrients or where it is very dry or wet. Pre-planting soil preparation should aim to improve these conditions.
Plant as soon as possible: Arrange delivery after you have thoroughly prepared the site and are ready to plant.