You can make a garden planter out of an old wine barrel, but purchasing them from a store can be expensive. If you want to convert an old barrel, then the best thing to do is to find an unwanted wine cask, and cut it down to size. You may find that the barrel contains some of the old product at the bottom, and wish to clean this out. It is not necessary, but if you want to, there are a few old ways to do it.
Soak It Up
If there is a lot of residue in the bottom, place some wood chips inside the cask. These will soak up any remaining liquid. Leave the chips for a few hours in order to make sure that all the wine has been absorbed, and then pour them into the compost or recycling bin.
Brush It Out
You can also get rid of the residue by brushing it out with an old dog hair brush. This will stick to most of the residue and allow you to take it out of the barrel.
Do not add any chemicals to the barrel, as this can soak into the wood of the cask and then later affect the soil and plants.