Signs advertising Crimestoppers New Zealand's tip-off line will go up in Feilding on Friday.
Farmer Scott Guy, 31, was shot dead in the driveway of his Aorangi road home on the morning of 8 July.
The organisation hopes the signs will prompt someone to call with information that could help find Mr Guy's killer.
Chief executive Lou Gardiner says people may be afraid to come forward, but Crimestoppers always protects callers' identities.
The signs will be put up on roads used by large numbers of motorists.