hi, i have just brought some canna terra flores and have noticed that the NPK level is 2-2-4, does this seems a little low??

would it be any better if i feed my plants (which are about 6 weeks in to flower) some NPK 7-6-6 aswell or would mixing the two fuck things right up?

or is the terra flores good on its own? has anybody any past experiance using this?