Further inquiries by police raised the amount of unexplained income to $730,000; a figure the couple explained as having come from selling firewood, farm machinery and livestock.
In the High Court hearing, the farmer said he had sold 300 tonnes of scrap metal at $200 a tonne.
Asked where the $60,000 had come from, Ronnie de Wys replied: "From the scrap man."
He said it was a sale which had taken place in December 2007. Asked who ''the scrap man'' was, Ronnie de Wys said: "I don't know his name. All I know, all I thought, [I] just know him as Santa Claus."
The Court of Appeal judgment said the couple's explanations, if accepted, reduced the amount of money which could not be explained to $313,000.
The High Court ruling had found the evidence was not enough to "draw the inference that they had been involved in a significant criminal activity" although the amount of cash gave rise to "some suspicions about the source of funds available".
But the appeal court ruled the High Court judge "may have underestimated the combined force of all of the circumstantial evidence".
It meant the judge had already decided the police case had failed when it came to considering the money the couple had. "The financial evidence was therefore seen as having little or no probative value in relation to that issue."
The appeal court ruling placed weight on the totality of evidence, including testimony by contractors harvesting maize on the property that they had seen cannabis growing there.
One said that when he came to harvest the maize, the middle three rows were found to be missing.
In the area where the maize was missing, he saw a 40-metre wide strip of marijuana growing and claimed to see de Wys in the distance carrying a load of mature cannabis plants.
While the High Court judge had ruled the eyewitness evidence as ''unreliable'', the appeal court found that it was only the identification of de Wys that was unsure.
Instead, the judgment stated there was evidence of marijuana growing and someone carrying the plants away could be relied on.
Taken with the other evidence, it found: "The logical inference is that Mr de Wys was the cultivator of the cannabis and also the unidentified man who removed the cannabis plants and walked away with them towards a stand of trees."
The appeal court also found that remnants of cannabis plants found in the roof cavity of a house where the couple had previously lived more likely belonged to the de Wys rather than the current tenants. It also showed large-scale drying of cannabis.
The appeal court judges said the ''Santa Claus'' claim showed ''the inherent implausibility'' of the scale of the businesses which would be needed to produce the unexplained cash.
''It is simply not credible that, over the space of a few weeks (at most), an individual who was completely unknown to the respondents and who did not even give them his name or that of his business paid them $60,000 in cash for scrap metal.''
Police only found a small amount of cannabis at the farm when carrying out a search, leading to de Wys' conviction on a possession charge.
