Yates Veg & herb 2lt fish blood and & bone hose on: approx what area would it cover please. Thanks, Clive.

Currently use a watering can, but it's killing my back. Use approx 100 - 42 litre containers to grow veggies and have never been sure how much to use. Containers are packed together so coverage is pretty much the same as ground area would be. Greatly appreciate your help.