The deck in my back yard needs power washing, but it is surrounded by plants, mostly perennials and clematis. Can you suggest some cleaning solutions and/or methods to clean the treated lumber without harming the plants?

This is a difficult question to answer since new cleaning materials and methods come about every year. A good place to seek advice on which solutions are safe to use would be your County MSU Extension Agent (the phone number can be found in the phone book under the government section, county name, MSU Extension). Keep in mind that power washers can be damaging to plants just by the force of impact against the foliage so provide protection with canvas tarps or cardboard. If cleaning solutions are used, be sure to wash off foliage with your garden hose as early as possible and soak the surrounding soil as well to dilute any solutions that may enter the soil.