Hi Jacqui, I realise I am in Wellington so probably not much help anyway, but I have not ever seen any of the Urtica species in cultivation down here. The main reason would be they are stinging nettles and very hard to handle, so no wonder really. It may be a chance for your organisation to begin the growing of these species to use for your cause. You may be able to get them contractually grown if you ask the right sort of nursery, the plants would be a couple of years away from a decent size and usefulness, mind.