''We've been thinking about it for a while and there's no right or wrong timing for this, so we thought it might help with things ... help with the grieving process,'' husband Steve said yesterday.
Mrs Potter (53) went missing about noon on Monday, March 30, from the garden of her elder daughter Koren's Dunedin home.
Searches within the first 10 days involving police and hundreds of volunteers failed to find any trace of her, she has not used her cellphone or bank cards and there have been no leads since on her whereabouts.
''It's sad there's no finality and it's a bizarre situation but I guess we know in our heart of hearts something's happened to her and she's not coming back. There are two ways of coping - you could become a basket case or just remain strong and deal with it and that's what we're doing,'' her husband of 34 years said.
Southern police communications manager Nic Barkley said Mrs Potter's case remained open.
''It remains a missing person case and if any new information is received, we'll act on it, '' he said.
When all possible lines of inquiry had been exhausted, the case would be handed on to the coroner.
Mr Potter said the service of remembrance, on June 6, starting at 2pm, was open to the public and would take place at St John the Baptist Catholic Church in Alexandra.
The Potters are parishioners of the church.
''The family talked about it and we needed to do something, to have a service, for us, for the whole community really and for Denise, of course. It might help everyone move on a bit,'' Mr Potter said.
''The past couple of weeks have been the hardest ... It's starting to hit home all of a sudden that this is our life now, without her.''
The continuing support for him and the couple's two daughters was amazing, he said.
''We know we're lucky to live in such a wonderful community. When things go wrong and people support us like they have, it gives you a bit of faith in mankind and it does help you get through. Whatever happened to Denise happened for a reason, and even if we don't understand why, we have to deal with it.''
