When selecting trees and shrubs for your site, you have a choice as to how your plants are supplied. Usually, your decision will be between bare-root, root-ball and container grown trees.
This blog aims to help you make that decision, taking your project requirements and constraints into account.
Here you’ll find answers to questions such as: what are bare-root, root-ball and container grown trees? When can bare-root and root-ball trees be planted? What are the pros and cons of container grown trees compared to bare-root or root-ball trees? and, most importantly, how do I decide which type of tree is best for my project?
Bare-root trees and hedging plants are grown in fields, and are lifted as and when they are required – without soil – when they are transplanted. They are only available during the dormant period (generally November to March, although in very cold winters this may extend to April), after the tree has lost its leaves but before they begin regrowth in spring.
Bare-root trees are the cheapest option, and this is for several reasons: low-cost maintenance (they do not need annual repotting or an intensive feeding regimen), more available stock (they take up less space), and more cost-effective despatch (they are lighter and take up less space than either root-ball or container grown trees).
On the other hand, depending on your project schedule, opting for bare-root trees could result in lengthy and costly delays. Even in bare-root planting season, there will always be a failure rate of roughly 10 per cent, so you will need to factor replacement stock into your calculations. (To mitigate failure rates, we recommend incorporating bone meal or a similar root builder into the planting pit.)
It is also worth noting that bare-root trees will need to be planted immediately upon delivery in order to maximise successful transplantation. Logistical issues or errors could cost you dearly if a large consignment of bare-root trees is left unplanted for any significant time.
Bare-root trees that succeed may take longer to become established than container grown trees, because removing the soil from roots inevitably results in some damage. Equally, you can usually only transplant bare-root trees of up to 12-14cm so they will take some time to reach full maturity and impact in your landscape.
Bare-root trees are most suitable for areas which require a significant amount of tree planting, either during the right season or where schedules can be halted or amended to suit the planting requirements.
Root-ball (RB) plants are similar to bare-root in that they have been planted directly into the ground. However, when they are dug out, the soil around the roots remains intact and is wrapped in a biodegradable bag which will allow new root growth and can be put directly into the tree pit during planting.
A root-ball tree being planted. The hessian covering allows roots to grow through it and will biodegrade.
Like bare-root trees, root-ball trees have a limited planting window, from November to March. Planting them outside this time brings a high risk of failure. They are another economic option, though incurring slightly higher costs than bare-root trees because the size of the root ball and weight of the soil adds to the transportation costs.
Where root-ball trees really shine is when it comes to breadth of choice: nearly all species, in any size, are available in RB, so if you require a large tree for instant impact, this may be the way to go.
On the downside, like bare-root plants, root-ball trees have a significant failure rate because their roots have been cut. To boost the chances of success, RB trees are best planted soon after delivery and then watered rigorously during the first year.
As root-ball trees have lost many of their fine, fibrous roots, they can take longer to establish.
Root-ball trees are most suitable for easy-rooting species and are particularly good if you are looking for a very large specimen or particular species.
Container grown trees
Also known as containerised or potted plants, container grown (CG) trees will have been grown in a pot for at least 12 months, giving them time to establish a good fibrous root system – which, crucially, isn’t disturbed when the plant is transplanted. This gives them a very high success rate in comparison to bare-root or root-ball trees.
Growing trees, shrubs and hedging in containers extends the planting season and, theoretically, CG trees are available for planting all year round. In practice, it is best to avoid planting even container grown trees in frozen, sodden or very arid soil.
With potted trees and shrubs you have a far wider selection from which to choose, since evergreen and semi-evergreen trees never fully enter a dormant phase and are thus too sensitive to be lifted directly from the soil at any time of year.
An enormous variety of tree species are available container grown trees, and they can be planted year round.
Container grown trees are usually easy to handle, often quick to establish themselves, and can remain potted on site for longer before planting. This makes them a good choice if there is any risk of logistical issues or delays, because the trees will not be lost if they cannot be planted immediately after delivery.
CG trees also offer girth size of up to 30-35cm – and sometimes beyond – and this means they can be used to create instant impact in a landscape.
For all the flexibility and reliability that container grown plants offer, there is one key downside: cost. They require greater maintenance whilst at the nursery, including repotting and irrigation, and they also cost far more to transport, due to the extra weight. Container grown plants are typically between 30% and 50% more expensive than their bare-root and root-ball counterparts.
However, the higher prices are at least partially offset by the almost 100% transplanting success rate. Using container grown trees and hedge plants gives you a more stable budget, and you save on the substantial costs of replanting the losses you would incur by using root-ball or bare-root alternatives.
Making your decision
Many factors may influence which supply option you opt for, including project scale, specifications, timing and budget. However, there are some easy questions you can ask that may make your decision for you.
Review your site programme and plot completion. Are there plots that will require landscaping during the summer months? If so, these will require containerisation of trees, shrubs or hedge plants.
Can you delay large POS or communal area planting until the bare-root and root-ball planting season? If so, you can use the cheaper options for your tree-dense areas.
Are there any specific high-impact plants required? If so, root-ball or container grown trees would be indicated – if rapid growth and establishment is needed, container grown would have the edge, whereas root-ball trees might be necessary for very large specimens.