Kuranui College principal Geoff Shepherd was appalled students could visit dairies and "buy lollies, a can of coke and some cannabis".
"We've got a huge problem- [when caught using it] they say 'But it's legal sir'."
Mr Shepherd said it was an issue for the whole community.
"We're seeing the residual effects of their influence during school time, which clearly impacts on these students' learning and development. We need a community strategy to combat this problem."
Care NZ addictions counsellor Teresa Ahipene, who works in Wairarapa schools, spoke about the dangers of the products.
She saw about 30 young people each week with addictions issues, and worryingly many of them were 13 and 14, she said.
"The primary drug of choice is usually cannabis but the synthetic cannabis is making a big name for itself."
Mrs Ahipene said ingredients of synthetic cannabis were not made for human consumption.
"What is quite disturbing is the person who invented synthetic cannabis ... has publicly declared his concern over its use saying it can lead to psychological problems that may be irreversible."
Common side effects include a loss of reality, paranoia and anxiety and long-term effects are not known.
"It's quite scary because when they're asking about it [side effects] you can't give an answer about whether it's permanent. It's a bit of a Russian roulette."
Mrs Ahipene asks children if she had a bucket of chemicals on her desk would they pick it up and drink them?
"They look at me like I'm mad and that's what they're taking."
She had heard a lot of negative feedback from young users who say it is a lot stronger than cannabis with intense and ongoing side effects.
The Psychoactive Substances Bill, which will come into force in August, will require manufacturers to prove legal-high products are safe and will reinforce the restriction of the products to those over 18.
"Good luck with that I say because they're not safe," Mrs Ahipene said.
Senior Sergeant Carolyn Watson, of Masterton police, said kids were choosing to use the products because of easy accessibility and legality.
"The main reason they said for smoking it was that they could buy it from a dairy," Ms Watson said.
Constable Dean Fawcett said the sale of cannabinoids was purely financially motivated.
"If you can hit them in the pocket by choosing not to go to the store ... it's about getting the community behind it. There's a good groundswell, a lot know that it's not good and there seems to be a lot of people who are voting with their feet," he said.
