Just about any item can be a vessel for plants, from wash tubs to whiskey barrels to cast aside footware. All that is required is a side wall and a drain hole, which can be fabricated if need be. Once the imagination has run wild about what could be, it’s important to focus on fine tuning in order to have success with veggies and flowers in a container garden.
First, think about what will hold the soil in place. If you’ve chosen a flower pot, sure, that’s a no brainer. They have side walls and a pre-drilled hole to allow water to drain out. However, if you’ve chosen a wooden window box, make sure that it will hold enough soil for the eventual root system and that it “leaks” a bit – it doesn’t have to be a real hole, just an opening for water to escape.
Next, the soil. It’s important to have 2 types of components; one to hold water and one to let go of excess water. Compost and Canadian peat moss are examples of water holders, while bark chunks, perlite, vermiculite and sand are good water drainers. A healthy 50/50 mix of these works well. Many brands of pre-mixed products are available as well.
Finally, consider placement. Most outdoor container gardens are adapted for sunny sites, but if ferns and coleus are primary plants, semi-shade is more appropriate.