I have many high density plantings, primarily trees spaced around 3'
apart in rows 10' apart. Pruning at least twice per summer plus
thinning pruning in the winter is needed. Without enough pruning you
will get trees that are too dense and that in turn can reduce the
amount of fruit and bring on diseases. It has taken me several years
to learn how to keep the trees properly balanced; I have found the
European plums the hardest to control and the dwarf apples the
easiest. I use a modified vase system on most trees - it is a vase
but with from 1-3 scaffolds only. With only one scaffold the vase
becomes a spindle of sorts.
Scott
Maryland z6/7
[NAFEX] High Density Planting,
Scott Smith, 05/29/2009