The farmer-owned company, which is New Zealand's largest supplier of fertiliser, has bought six houses in Ravensbourne Rd and recently demolished three of them.
"We purchased the properties to future-proof the fertiliser manufacturing business and to improve vehicle access to the site," Mr Gray said.
"For example, most recently, we have widened the road alongside the entrance to the fertiliser works. This has improved visibility and safety for vehicles turning into the works and also for the state highway traffic."
Mr Gray said the fertiliser plant faced space constraints on its harbourside site.
Owning property on the hill side of State Highway 88 gave Ravensdown more options as it looked to the future, he said.
"The business is changing. We are now exporting to Australia and need to ensure we can meet future demand."
Ravensdown had rented out the houses it owned, but the cost of maintenance had increased and a couple of untenanted houses had "come to the attention of squatters and vandals".
In the past two weeks, three houses were demolished. The vacant sites will be landscaped.
"A comprehensive landscaping design plan has been established with a local landscape architect, Don Barham, in consultation with the Ravensbourne Works Community Liaison Group," Mr Gray said.
The company wanted to minimise its impact on neighbours. Fewer houses close to the plant would help that, he said.
At this stage, Ravensdown intended to continue owning and renting the other three houses it owned in Ravensbourne Rd, Mr Gray said.
The company would look to buy more properties "if and when they come on to the market", but did not have "endless capital".
The Ravensbourne plant is one of three Ravensdown owns nationwide. The other two are in Christchurch and Napier.
