The ideal plant size is 35-45cm otherwise the shoot may be out of balance with the roots and the plants will be unstable. At this ideal size they do not usually require staking since any rocking motion will serve to strengthen the young trunk. On exposed sites it is nevertheless recommended to use a short sturdy stake, minimum of 5cm (2 inches) in diameter and tied no higher that 30cm (12 inches) to prevent initial socketing which can tear the roots around the root collar and lead to later instability.
Large Eucalyptus plants grown conventionally in round pots are a liability. The roots continue to grow in a spiral direction (see the section on fabric containers). Polybags help to prevent this spiralling by trapping the roots in the folds of the bag. Large plants in small pots are usually pot-bound, take a few years to recover and are often subsequently unstable. In rudimentary experiments plants of the same species that had been grown on for two years in 30cm (12 inch) pots and were about 1.5 metres (5ft) high were planted out and compared with younger plants of 35-45cm high that had experienced no check due to root restriction. The smaller plants overtook the larger pot-bound plants in less than one season and continue to out grow them. The plants that were planted smaller are also more erect and wind-firm.
Also the common problem with Eucalypts planted too big with a small root system is that there is an imbalance of root and shoot and the root fails to catch up with the top growth. They will grow very 'leggy'. This can be compounded if they are planted in shade. The tree begins to lean, rocks around and will eventually blow over. It is certainly not advisable to plant large Eucalypts grown in round containers for these reasons. Also by the end of their first season smaller plants will already have outgrown larger pot-bound trees. Our nursery practice ensures the plants will not be 'leggy' or pot-bound but will have a good strong young trunk and a good root-shoot ratio. |
