plant safety, roofing material too

Looks like I am going to have to strip old Thompson's clear water seal off of a redwood balcony that is above a landscaped garden. Tarping will be difficult due to the nature of the plants. Can I safely use a stripper (probably Restore-A-Deck) and brightener if I really wet down the plants before and after the treatment? If not, should I just sand? (That would be a ton of work). There is a second new redwood deck on the new roof. The roofing material is modified bitumen. Can I safely use a deck cleaner and brightener on that if I wet it down before and after? REALLY don't want to compromise a brand new roof! Many thanks.