New gardener from the UK here. I am growing kale (Nero di Toscana) in garden containers, and so far this year, so good! Unfortunately when I tried this last year, they were completely demolished by cabbage white caterpillars. I have purchased some netting to try and protect them, but can't figure out the best way to actually cover the containers; all the online advice I have come across seems to refer to plants in beds, which can have some sort of row covering. I don't have space for planting outside of containers. Is there a commonly used method for constructing netting to protect containers from pests?
For cabbage moth/loopers netting should be quite fine, of the order of 5-7mm. square rather than 15mm. If the 15 is all you have available might want to double up the layers if you have enough. Row covers (very fine netting) are often supported by wire hoops, but plain netting can be supported by sticks and branches stuck in the soil in various strategic locations - the thick ends are good for shoving in the ground, and the small twiggy ends are good for gentle contact with the netting. Make sure the nets are tied down well at the edges since wind can have a devastating effect on netting that is loose.
If you are growing in large pots you could consider using tomato cages to hold the netting off of the plants.