The landlord is required to provide the property (including facilities) in a reasonable state of cleanliness. In doing this, they should take into account all building, health and safety requirements that apply to the property. Where this is not done, the tenant should notify the landlord and may issue a notice for the landlord to remedy the breach.
Tenants should keep the property reasonably clean and tidy. This includes weeding and mowing lawns where the landlord has not accepted responsibility for this under the tenancy agreement. Tenants should also leave the property reasonably clean and tidy at the end of the tenancy.
Where a tenant fails to keep the property reasonably clean and tidy during the tenancy, the landlord should notify the tenant and may issue a notice to remedy the breach. When the tenant fails to leave the property reasonably clean and tidy at the end of the tenancy the landlord may seek to recover reasonable costs incurred to return the property to a reasonable standard.
It is an unlawful act if a landlord does not comply with their obligations regarding cleanliness, maintenance, and relevant building, health and safety legislation.
Source: http://www.dbh.govt.nz/tenancy-az-c