How many meters does the Triangle Palm grow in a year in Victoria i.e. how tall would this palm be from seedling stage to a year gone by?

Hi there,
I would expect to see around 1/2m -1m of growth, depending on care. You will see faster growth from when the palm is young, than when it starts developing a trunk. Once the palm gets older it will gain heigth slower as it will be developing overall, rather than just focussing on height.
With regular use of slow release fertiliser, watering, mulching and even regular applications of foliar feed you can get quite good growth rates.
Kind regards, EL