Perenialising (sic)

I have a screen saver, offered by a bulb company, which wafts a tasteful series of delicious plant portraits across the screen. This morning, I actually read some of the text and noticed that one plant is 'also good for perenialising'. Apart from the fact that if such a verb exists, it should surely be 'perennialising', what on earth does this mean? To perenialise: to stick a plant in garden soil and leave it there to come up every year. Why wouldn't you do this? Because you are so used to 'containerising' your plants, is why.