The secret to finding a tree that will flourish when planted is to look down as well as up! Trees can absorb water from the tips of their youngest, finest roots, so an undisturbed, fibrous, non-spiralling root system will serve you best.
It is very easy for an unscrupulous grower to sell trees at knock-down prices by skimping on root cultivation, so our advice is to ALWAYS check the root specification before buying a tree, see below for an explanation of the main options available:
The choice you make when buying a tree
The AirPot is a proven, revolutionary growing system which overcomes the root-spiralling problem of conventional container grown production. It is truly ingenious design solution, made of a sleeve of recycled and recyclable HDPE (High Density Polyethylene) that is textured like an egg carton, with small holes at the tip of each cone.
As the outward growing root tips reach the boundaries of the Air-Pot, the cones funnel them towards the holes, where they eventually dehydrate upon exposure to the air. The effect is a constant, gentle root pruning, which stimulates the root system to send out lots of lateral roots, similar to pruning the branches of a shrub.
The result is a highly robust, densely fibrous root system composed of thousands of water absorbing white tip roots. Essentially Air-Pot grown trees are bursting with vitality. They can be planted any time of year with a virtual 100% success rate, are the fastest and easiest trees to establish, and will become far superior specimens over time.
Field grown trees are cut out of the ground and soil shaken off to economise on weight. Cheap and cheerful, that's fine for easy-to-root varieties and broad scale planting (woodland planting, young hedging), where a high failure rate is acceptable. Bareroot trees can only be planted in winter. Expect a significant failure rate – up to 50% or even higher at times. Bareroot stock is seldom guaranteed.
Field grown trees are cut out of the ground and wrapped in Hessian sacking with the soil left intact. Quality growers will have regularly transplanted and undercut the stock before the final lifting for sale – but skimping on undercutting is an easy way to cut costs. Rootballed trees have had their roots cut at lifting, so they have lost most of their fine fibrous roots, and can only be planted in winter, take longer to establish, and have a significant failure rate, varying by species. Using rootball stock can be an economic way of planting easy-rooting species, but requires careful aftercare provision to ensure success.
Conventional Container Grown
Field grown trees are lifted and planted into plastic containers to allow roots to regenerate prior to planting. A more expensive but better value method, compared to bareroot and rootballed, with a good success rate that enables year-round planting. The main disadvantage of the container method is that it does not promote production of fibrous root system, but rather the familiar ‘pot-bound’ effect of thick, spiralling roots, which are not very efficient at water absorption.
Similar to the container method, bags are used for ease of handling (and manoeuvrability). Convenient, but as shown in the photograph, roots typically hit the sides of the bag and are deflected downwards. Better than bareroot, rootball or a conventional pot, but greatly inferior in root development to an Air-Pot grown tree.