Root pruning
When transplanting trees in the nursery, it is important to develop a good, fibrous root system. This is achieved by pruning the roots.
Use a pair of clean, sharp secateurs to make the cut. Dirty or blunt secateurs might cause the roots to rot. Cut the main tap root leaving at least 15cm of root. If you cut too much, most of the plant's strength may be lost and it might die.
Transplant the young tree to the same depth as it was previously growing - there should be a mark on the stem showing this point.