Only six of 42 trees planted in Masterton's town square are expected to survive, the rest dying through lack of proper care and water, landscape designer Lyn Eglinton said this week.
Mrs Eglinton said many of the trees now dead or dying were second-time plantings anyway, replacing the original trees planted when the square was first constructed in 2013.
She said when she had inspected the trees last week she found them to be " in an awful state".
"I've never seen anything so bad, it was appalling."
Adding insult to injury the base of the trees had been surrounded by "horrible matting" and then expensive granular fertiliser had been sprinkled on it. "Not much use fertilising dead trees," she said.