Phormium plants

Probably not, but only time will tell. You've done the best thing by planting it out - if the plant is virused or has a disease of some kind, it may not do well anyway, but if its a result of being trapped in a pot, it'll do fine. Only thing I'd suggest is to check for Phormium mealybug - you need to inspect the base of the plant, particularly inside the sheaths (this may mean pulling one out slightly) for white, fluffy deposits. Most Phormiums get it now in this country, but the health of the plant seems unaffected if grown in the border, whereas in a pot, they seem to suffer badly if they've got it and don't grow so well. Treatment is spraying with Malathion, though I'm not sure its still available.

Many phormiums in pots struggled or died last winter. The fact that it has survived is encouraging

I have several, love them - and agree that now it's 'free' it'll probably establish well.
Give it some tender loving care and it'll come right in no time.

You've changed the pic, Mattyscott! That one's doing well, for sure. I've got 3 phormiums in pots, had 'em for a long time, they came through last winter, snow and ice not withstanding, very well - but they do suffer with the dratted mealybug.

There was only 1 type of Phormium that i had problems with and they weren't 'this' type of problem at all but i'll tell anyway !

I had 2 P. 'Platts Black'.
Gorgeous liquorice-black, strappy leaves - but ..... they weren't stiff upright leaves at all.
These leaves were soft and floppy and the plant was a constant source of disappointment because of it and in the end i dug them up and gave them away !

I've got a yellow and green variegated one (forgotten the varietal name) and that's floppy too, but I don't mind that, I quite like it - the other two I have are relatively floppy as well, specially compared to Cordylines. It may be that P. tenax varieties are stiffer leaved than "cookanium" cultivars, what do think?

Hmmm, didn't even consider that, i'll read-up on it !

I have several Phormiums (10) & they are tough plants. Just take it out of the pot, five it lots of TLC when planting & U will be surprized how it thanks U. Good Luck. They will survive better in the ground than pots.