We have an established hosta. About midsummer it starts to look pretty sunburned. At what point should I cut it? It is on the south side of our house and gets full sun after mid morning.
You may want to consider moving your plant to a shadier location so that looks better in the garden.
You can clean up the plant but really should not trim it back totally until early fall so that the plant stores some energy for the winter.
Here is some links for you.