Leeson Lavender, from Stoke, was helping Eden Maddocks - trading as Eden Creative Landscapes - to install a large oak post at a property in Keele when the fatal incident occurred on 20 May 2010.
At Stafford Crown Court on 11 January, Maddocks pleaded guilty to breaching Section 2(1) of the Health & Safety at Work etc Act 1974. He was given a suspended prison sentence and 180 hours of unpaid community service.
The court heard that the two men had stood on a trailer that had been used to transport the post and had started to manoeuvre it towards a pre-dug hole. As they lifted it, the trailer shifted, causing Lavender and the post to fall out.
Lavender hit his head on the ground before the post struck him on the head. He later died from his injuries.
The court heard that an investigation by HSE found that Maddocks had successfully used this method of work on other occasions, but this time the oak post was larger and heavier than he was used to dealing with.
HSE inspector Lindsay Hope said: "Mr Maddocks had balanced the trailer with sandbags and provided stone chocks to stabilise it during the lifting process. He had also provided guide nails in the trailer to stop it sliding sideways during transportation, so he had obviously considered the potential stability issues and had taken some precautions in an attempt to reduce the risks of the post overbalancing.
"Sadly, he didn't do enough and Leeson Lavender paid with his life - a tragic and unnecessary death that could have been avoided."