What happens next?

How to stop cats from digging in flower beds
Squirt lemon juice or scent on your flower bed.
Lemon is a citrus fruit, and many cats hate the scent of citrus, and will be instantly repelled by the scent. Lemon zest is better if the flower plants are growing, but lemon juice is perfect if you have fully grown flower plants to dodge.
Drizzle orange oil on your flower garden. Again, many cats absolutely hate the scent (and taste! ) of citrus fruits.