Police said the growing operation was sophisticated and based on estimated yield and price per ounce, Price could have made between $86,000 and $260,000 a year if sold.
Price said he had suffered a raft of serious health issues over the years, including prostate cancer for which he had surgery about 12 years ago.
"I'm still under the care of a urologist,'' he said.
Price presented a letter from a doctor which listed several medical issues.
The letter confirmed Price had been treated for prostate cancer in 2007 and continued to be under the care of a urologist.
It also listed other medical issues, including that he had a heart disease after suffering two heart attacks and previously had surgery and treatments for chronic back pain.
Price said he also had a back operation about 20 to 30 years ago, but said he needed more surgery.
"My legs are stuffed and because of my chronic back pain as well, I can only walk about 100m before I get dizzy and my legs start to collapse under me."
Price said he wanted to buy a $3500 German-made electric wheelchair so he could be more mobile and wanted to travel to Russia to have a top surgeon perform back surgery.
He said he never intended carrying on the cannabis growing operation long-term.
"I just wanted to make enough money to buy the wheelchair and have another back operation, and then I would have shut up shop," he said.
"I'm old and frail and I just wanted to have a bit of better quality of life in my old age."
Price said he initially started growing plants in the ceiling of the home but then moved to the shed on the property because his wife went berserk about the smell.
He said he had learned his growing skills when he used to grow orchids in large ponds on the property, and also had previously bred tropical fish which he sold to pet shops.
The Tauranga-born retiree said the involvement in cannabis cultivation started with a few failed experiments and had wasted a lot of money at first doing so.
Price said he had not sold any of his cannabis product but was stockpiling it until the sale price got better.
He said he would never sell any of the cannabis to people with serious health issues but he was prepared to give it away.
Price claimed he had previously given some to a person who passed it on to a cancer patient, and only planned to sell the drug in pound lots to people who could afford to buy it.
In court, Judge Christopher Harding told Price he needed to get his affairs in order.
Price told the Bay of Plenty Times he was not worried about going to prison, it would not be the first time he had been there.
He said in the 90s he was involved in a bird smuggling ring, where they hired a plane and flew native parrots over to New Zealand from Queensland.
Price said he was sentenced to 16 months' prison, but ended up serving six months.
The ring involved 20 people, he said.
Price said his fate would now be up to the judge.
"I believe we come on to this earth to learn lessons, and while some things are pre-ordained, this is clearly one of life's lessons."
Price is due to be sentenced on September 14.
