What type of visa do I need?
Although hosts consider WWOOFers to be volunteering, the Immigration Dept says that if “gain or reward” (ie food, accommodation) is received while volunteering then they consider volunteering to be work. This means, if you say that you are coming to “volunteer or work on a farm” the immigration department in New Zealand require people to hold an open work visa such as a Working Holiday Visa (WHV) if they will receive food, accommodation while volunteering.
For more information please go to https://www.immigration.govt.nz/new-zealand-visas/apply-for-a-visa and select the country you are from.
WWOOFers from Australia do not require a WHV . If you are from USA, Canada, England and Ireland you may be able to apply for a special visa valid for people aged 18-35 year from BUNAC.org.
Unfortunately WWOOF can not help you gain the appropriate visa.