I love the idea of using baskets in soft-grey rattan for planting. These have been simply lined with plastic bin bags, with their bottoms pierced for drainage. -- Modern Country Style: Leopoldina Haynes' Small Garden Click through for details.
Magnolia 'Little Gem'-easily controlled to te height range that suits your requirements ben. Will generally form a clipped block of foliage over time though not as dense as the lilly pilly we chatted about. *Could be used as a "pleached" hedge(st