I'm still pondering what it is about garbage cans that make them such effective containers, besides the fact there's no less expensive big pots....is it the contrast between shiny, hard, man-made metal and soft, organic plants? There's great visual satisfaction in the high-low mix of sumptuous plantings played off galvanized garbage cans. And it doesn't hurt that plants thrive in the deep root run and reflected heat. Whatever it is, garbage cans make great containers for trees, sophisticated mixes of foliage plants, vegetables, or big bouquet-like compositions.
Garbage cans read neutral, yet they're also visually strong enough to work with hugely contrasting bunches of plants like these two cottage-gardens-in-a-can at Bayview Farm and Garden on Whidbey Island: