Espaliered trees when there is no supporting wall or fence

Meg_ryan100

My husband has asked me to provide a support structure for several trees that he wants to grow as espaliered trees.  However,  there’s no support wall or fence, so I’ve installed wooden fence posts at each corner of the plot and tied wire between them.  

My question is what distance should I leave between each fence posts in order to avoid the wiring sagging when it expands slightly in the heat?  I’ve read that it’s best to put one fence post in every three feet, but that seems pretty excessive.

pansyface

Are they apple trees? Some varieties have stout branches, some have thin, whippy branches. Imagine suspending a bag of apples from a horizontal branch that is not too sturdy. Add on a bit of weight on for rainwater and then add the stress and strain created by a frolicsome summer wind.

I’d say every three feet sounds about right.