Scotland's Native Trees and Shrubs
The downside of buying on the open market
Landscape contractors currently procure the majority of their nursery stock on the open market. The designer and client must rely on their contract requirements, specification and quality management system to control the procurement process. Unless the contract contains a selected list of nurseries from which the stock shall be bought, the contractor can buy the stock of the prescribed quality from wherever it is available at the lowest cost. Assessing the 'prescribed quality' can cause difficulties for there are no simple ways to determine the health and fitness of some plants, especially the deciduous species when not in leaf. A fairly detailed knowledge of their upbringing is required to make this assessment.
Other safeguards are therefore necessary. One method currently favoured by the Scottish Executive is to firstly specify a high quality plant, diligently monitor the contractor's procurement process and subsequent performance and then, in the event of failure, require all defective plants to be replaced with more expensive plants than originally planted.
This method is thought to be preferable to relying on prescribed performance of plant growth at various intervals after planting. For example 'the tree shall be two metres high at the end of the establishment period and three metres high at the end of the maintenance period'. The variable conditions on a road scheme that may be many kilometres in length is such that performance cannot fairly be prescribed accurately and, in the event of non-compliance, improving performance can be unrealistic.
Scotland has a wealth of flowering species. We should use more of these species in our own designs.