Field performance of outplants is influenced by planting depth; the effects are most evident at the extremes, when planting is either excessively shallow or deep. Planted stock cannot overcome massive exposure of roots, insecure anchorage, or burial that places roots in inhospitable conditions, unless adventitious root development can compensate for these problems. Somewhere between these extremes lie ideal planting depths, which for a given species probably vary with stock type, age class, condition, and site factors. Little data, most of which are not statistically valid, have been published on the subject.
One reason given for unsatisfactory plantation performance has been "planting loo deep". With remarkable unanimity, writers have stressed the "golden rule" that, in transplanting or outplanting, a tree should be set into the ground at precisely the same depth at which it was growing in the nursery. This seeming logic is nevertheless flawed: a nursery-grown root system, whether or not modified during lifting, storage, or transporting, will differ from a root system that has developed in-situ. Major adjustment will be needed before un outplant's root system becomes reconciled with the rooting medium into which it is introduced. In fact, deep planting is not necessarily detrimental and can even be beneficial.