Do you need new soil every year in wine barrel containers , or can you enrich the dirt from the year before? I always plant tomatoes in them along with a few flowers and herbs.
Container. Gardening Dirt
Certified GKH Gardening Expert
There are a few ways to go about this.
I recommend changing the soil out every year, or at least amending the soil with compost, dolomitic lime, and iron sulfate before putting it back in.
You can also plant beans and peas in the off seasons to help replenish some nutrients such as nitrogen.
But the best thing would be to use an all new potting mis amending with organic material.