Understanding the Form Specification
(the cultivated shape)
Trees can be encouraged to grow in a range of different ‘forms’ by formatively pruning them at key stages of their development. For example, hornbeam can be grown as a hedge, a pleached tree, or an enormous stately lawn specimen. Deciding on which ‘form’ will best suit your space is an important stage in the selection process. It is also important to know which size specifications are most important for trees of different forms (You can read more about size specifications on the Understanding Size Specifications page).
Below is a guide to the conventional cultivated ‘forms’ available, along with their key size specifications:
A ‘standard’ form tree has a single straight trunk clear of lower branches for at least the first 1.8m (6ft). If you desire your tree to be of ‘standard’ form once mature, it is crucial that you verify that the specimen you are purchasing either already has a clear 1.8 meter straight trunk, or, if buying a very young tree, that the specimen has a straight central stem running from root to tip with no bends or forks. In the latter case you will need to carry out formative pruning as the tree grows to ensure the trunk continues to grow in a straight manner and produces a balanced framework of branches as the crown develops (this isn’t as easy as it might sound!).
‘Standard’ form trees should always be specified by girth size, with pot size an important secondary specification.
A ‘half-standard’ tree is a tree a single straight main trunk cleared of lower branches for the first 1.2 - 1.5m, often grown for a small garden bed or container.
Half-standard trees should be specified by both girth and pot size.
A ‘quarter-standard’ tree is a tree with a single trunk cleared of lower branches for the first 1 meter (or less), usually grown for a decorative pot on a patio bed or raised planter.
Quarter-standard trees should be specified by both girth and pot size.
A ‘three-quarter-standard’ tree is a tree with a single trunk cleared of lower branches for the first 1.5-1.7 meter (approx), branching at about shoulder height. It is not a widely used definition, yet trees of this form are commonly seen in gardens and landscaping. We feel it important to distinguish full standards (with head clearance) from slightly shorter single stem trees whose crowns are too low to easily walk under.
Three-quarter-standard trees should be specified by both girth and pot size.
A ‘feathered’ tree has a single dominant, straight trunk running through it, but has lateral branches from the ground up.
‘Feathered’ stem trees should always be specified by height and pot size.
A ‘multi-stemmed’ tree has multiple stems from near the ground. A true multi-stem has one trunk that is cut off near the ground when younger (above a node) and then multiple buds appear and at least 3 are grown on to develop into a lovely tree. However, some so-called multi-stemmed trees are grown as 2 or more trees planted together when young.
Multi-stem trees should be specified by height and pot size.
A densely branching multi-stemmed tree without obvious dominant stems, or a woody plant which is classified as a shrub rather than a tree, having a natural mature height being less than approximately 3 meters. Camellias and Viburnums are classic examples.
Shrub-form specimens should be specified by height and pot size.
As one would expect. Stock which has been subjected to formative pruning to produce specimens of a uniform shape with a thicket-like habit which becomes denser with increasing maturity, usually taller rather than wide, and ideal for planting in multiples. When this term applies to ornamental varieties, varieties cultivated for hedging will have had less detailed formative pruning so the finish will not be as pristine as one cultivated to a more ornamental form (such as a feature tree or topiary shape), and the price will almost always be less (like for like size wise).
Hedging specimens should be specified by height and pot size.
As a form, we define a Climber as a woody stemmed vine that would require training onto a structure. Wisteria and grapevines are classic examples.
Climbers should be specified by height, pot size and what they are trained onto (i.e. fan, cane, etc).
A ‘pleached’ tree has been trained onto a frame (usually a bamboo frame) of varying proportions/sizes to produce a highly structural effect. A typical pleach will have a 2m trunk and a 3m x 2m flat panel on top to be used for aerial screening above a fence/wall or as a feature. However, many other forms are available, including box head, roof and umbrella pleaching, or low fence-panel style pleaching. Pleaching is also often used in various configurations to soften a wall or grow fruit trees along a wall. Pleached fruit trees are often described as ‘espaliers’.
In our stocklist, we find it useful to denote these variations in pleach forms as depicted above.
Pleached trees are usually specified by girth size (if standard form) and pot size, along with dimensions of any less conventional pleached elements.
Topiary forms have been intensively cultivated to produce a wide range of highly ornamental shapes. We have a range of form categories for our topiary stock, as above, but there are new and interesting shapes arriving all the time, such is the nature of topiary! We highly recommend viewing in person to appreciate the options.
Topiary form stock is usually specified by a combination of description, dimensions and pot size.
All technical terms aside, we strongly encourage you to avail of any opportunity to personally view and select your trees in person. There is no better way to appreciate relative size and quality. Trees are one of the few things in life which cannot be mass produced in exact duplication. Each specimen is unique, which is precisely what makes them so wonderful!