Q&As/Vegetable Gardening or Soil Rejuvenation/Fresh Soil for Containers
While it is possible to ‘pep up’ your existing soil in the various containers you mention, we would strongly advise starting the new season of vegetable growing with new potting or container mix. The reason for this is because after two seasons of successful cropping, the soil in your containers will not only be depleted of essential nutrients, but will have lost some important structure that could lead to drainage or water retention issues.
Emptying your containers provides an opportunity to clean them to reduce possible fungal infections, and you can also check that the existing drainage holes are sufficient.
Remember, even when using new potting or container mix, it is important to apply slow release fertiliser during the growing season to ensure your veggies grow strong and healthly throughout the season.