The Root System
The root system must be well-developed by good nursery practice influenced by the natural characteristics of the species/cultivar, taking into account its age and growth rates under the cultural and growing medium within which it is growing. The system must not show any coiled main roots close to the collar, nor any physiological damage.
The root system must not be allowed to dry out at any time. Plants are supplied:
These are typically shrubs grown from seedlings, hardwood field grown cuttings and then transplanted are supplied bare root.
All bare root systems must be supplied in bags, containing and enclosing the whole root system. Seedlings, cuttings and transplants (up to 30-40cm overall height) are typically supplied with shoots and roots fully enclosed in the bag, whereas for larger shrubs, if lifted bare root, only the root system is enclosed. Ideally the bags should be manufactured from co-extruded polythene – black on the inside and white on the outside.
Shrubs must be supplied bagged unless any other protection (rootball, container grown) for the root system is specified.
The following types of shrubs are typically supplied with a rootball, if they are not container grown: Evergreen species and cvs.; Field grown deciduous spp. and cvs. usually over 1 metre height.
Rootballs must be firm and solid and the roots must penetrate the whole ball. They must be enclosed in hessian (burlap). The size of the rootball must be appropriate for the species/cultivar and its age and growth rates under the cultural and soil conditions within which it is growing. The rootball must be free of perennial weeds.
For Specimen conifers, the rootball will be additionally protected with ungalvanised wire netting, wire basket, spring ring, root control bag, tree cradle or custom built container.
All materials used to support rootballs must decompose within eighteen months of planting and not constrict the continuing growth of the plant.
Container grown plants should have been grown in the container for sufficient time for the root growth to have substantially penetrated the medium but not be root bound. The rooting must be well balanced in accordance with the container size.
Plants are to be centered in the container, well rooted, firm and moist on delivery, with the growing medium coming within a suitable depth of the pot rim, taking into account the size of the container and the age since potting.
The surface of the growing medium shall be free of all weeds.
Plants shall be supplied in rigid containers or polybags. If polybags are used, then this should be stated. Container grown plants are defined by the letter ‘C’ followed by a number indicating the volume in litres, e.g. C5. Small container sizes (less than 2 litres) are referred to as Pots. Pot grown plants are defined by P followed by a number indicating the upper, outside width in cm, e.g. P9.
Cell grown shrubs, which are usually seedling in form, combine growing the plant in a container (a cell) and then supplying the plant as a complete rootball, bundled together, protected with plastic and supplied in boxes.
Cell shrubs are specified by ROOT VOLUME (Container size), HEIGHT and ROOT COLLAR DIAMETER.
As with all plants, specifications cannot be rigid since growing conditions will vary from year to year but the information in this specification gives the general standards for growing cell plants. Again, as for other stocks, larger plants can be grown on contract.