William Jones was worried about the financial implications of the weed spreading onto public land adjacent to his.
At Smethwick Council House yesterday, lead coroner for the Black Country Mr Zafar Siddique concluded that Mr Jones, known as Bill to his friends and family, of Brettell Lane, Amblecote, died by way of suicide.
The inquest heard he was found hanged at home by one of his sons on February 13.
At the hearing, Mr Jones' wife Helen said her husband, a former butcher, owned a piece of land in Brook Street which had recently been surveyed and revealed that Japanese knotweed was growing on the site.
She said: "He was worried about the financial implications of it, it grows so rapidly.
"He was a family man. If he had thought it through I'm sure he would have never gone through with it."
Mr Jones had been expected to pick up his wife after a shopping trip on the day of his death, the inquest heard.
"He sounded quite cheery on the phone," Mrs Jones added.
"But then I made three calls to the house and he didn't pick up. So I called my son who went into the house and found him."
She said her husband had no financial worries when he died. She added he was worried the weed would spread onto public owned land next to his land.
Mr Jones, aged 69, who had a history of depression, was taken to Russell's Hall Hospital in Dudley.
He was suffering from brain damage and died a day later on February 14.
The cause of death was confirmed as hypoxic brain damage due to attempted hanging.
"Bill was the type of person who always liked to find the answer to things," Mrs Jones added. "But this is one thing he couldn't find the answer to."
In March 2014, an inquest heard how a lab technician murdered his wife before killing himself after being driven 'mad' by Japanese knotweed growing over his house.
Kenneth McRae and his wife Jane were found dead at their home on Bryan Budd Close, Rowley Regis, on July 17, 2013, after his colleagues raised concerns that they had not seen him.
Mr McRae was found on the first floor, his wrists and throat having been cut, and Mrs McRae was found in bed on the second floor with head injuries.
A suicide note to West Midlands Police revealed Mr McRae had a 'growing madness' over some Japanese knotweed that he claimed was creeping onto their property from a neighbouring golf course.