Detective Sergeant Jackie Adams said Jones' body language suggested there was more to be found.
"He wouldn't stop talking, wouldn't stop moving and he kept looking up at the ceiling, so we climbed up and found the three boxes in a space above the cylinder."
The boxes, in a gap above the hot water cylinder, contained 500g of drying cannabis head.
Brett Geer, the detective sergeant in charge of the Tasman police organised crime unit, said the cannabis found at Jones house was worth $5820 if it was sold by the ounce.
Mr Geer yesterday gave the jurors a quick lesson in "drug speak" to help them understand texts to and from Jones' phone. The texts included "O's", "s" and "hundies". Geer said that was drug-speak for ounces, half-ounces or hundreds of dollars.
In evidence, Jones contended that the "Os" referred to rings of firewood and the "hundies" were bags of whitebait he had for sale.