I have some Lilli Pilli in pots - Acmeni smithii - that were sited to provide a screen. I have now moved and could plant them in the ground but I wonder if that will be successful or if there roots will not develop. They are in pots around 500mm deep and are approx 1 metre high.
Hey Kathy, Acmena smithii are quite hardy and vigorous but you'll need to tease the roots out when you de-pot them, this will help them get going quicker. The danger of pots for larger plants is that the roots tend to grow vigorously (expecting to have plenty of soil to reach out into).
The result is often spiraling roots that circle around the pot, growing into a dense mass. This becomes a habit so that when you plant it out those roots can just keep doing the same old thing, unless of course you intervene.
Don't fret about disturbing the roots, its better to trim some off and open up the root structure as you plant them out.
Also remember that they will grow fairly tall if left to themselves, (up to 15m or more) so if you want a medium or low hedge then you'll need to keep them pruned or topped.