I had what they called "dirty dishwater blonde" hair while growing up.
My favorite part of summer was getting those natural highlights in my hair, I so looked forward to hot summer days at the beach, lake, or swimming or even with the hose. I used to use lemon to speed up the process, but I dont really recommend it now because it does dry your hair out. But in summer lots of girls like to have that crazy, dry, blonde streaked hair.
My suggestion is not to use fake products and to just be patient and get excited about summer. Her friends will be envious, no one envies something you can buy in a box. Not that I'm promoting envy, but I know how teenagers are and your daughter wants to jump the gun. Let it happen natural!