Nettles are absolutely essential for the butterflies of our 5 most popular species to raise their caterpillars. These butterflies require stinging nettles because they keep the caterpillars safe from grazing animals.
Not all butterflies require nettles. The ones that do are - Peacock, Red Admiral, Painted Lady, Small Tortoiseshell and Comma. Others, such as cabbage white, will use other plants. If you're happy with cabbage whites, then planting a few cabbages or nasturtiums is an alternative. Personally I prefer Peacocks and Red Admirals
As far as the gardener is concerned there are two drawbacks to nettles. If touched, even accidentally, they can sting. And they spread easily by means of their invasive shallow roots.
The solution demonstrated at Hampton Court solved both of these problems. A pot, placed in the centre of the flower bed, removes then from acidental contact, caused by brushing against nettles while walking past the flower bed. And putting them in a pot restricts the root spread.
Here are two pots I planted up yesterday morning...
I thought that holding them up while tying them to the canes might be tricky, as you can't tie string wearing gardening gloves. So I did it with bare hands, carefully, and was not stung.