Wouldn't these 8 planters and small trees look beautiful lining the aisle at your wedding...
Any plant, small tree or planter would work really! So that opens the door to lots of options depending on your style and/or theme - metal, tin, wood, ceramic, or even plastic. Think urns overflowing with flowers for a garden theme, wooden barrels or apple crates filled with small apple trees for a natural/rustic theme, terra cotta pots filled with olive trees for a wine country theme, ceramic pots filled with elephant ears for a tropical theme...I could go all day, but won't subject you to all my ramblings...but all would look stunning!
They would also look great lining the walk up to a tent, inside the tent as decor...possibly to define you dance floor. Four of them would work as a place to say your vows...if you use plants, you could add poles and material to make your own tent area - or to shade a seating area.
Or you could go another route entirely - fill them with ice and add bottled water, soda, beer or wine. It might be a small investment depending upon the type of planters and plants you buy, but you can always use them after the wedding - on your front porch, in the backyard or even inside!
...photography douglas friedman