Magpies eating hostas - help!

We have an issue with magpies in our garden. They’ve been around for a long time, however this year they have become a particular nuisance. I have had several pots with hostas in for some years, but moved the pots into my lawn for a few days, and the magpies completely ate two of them right down to the roots! I have now had to hide the rest of the pots and I don’t know how to stop them from eating the rest - can anyone help with ideas? Any idea why they’ve found the hostas so attractive?