Q: We have a cement patio at the rear of our townhouse. After a damp summer and fall here in the Northeast, it has gradually turned greenish-black. How do I clean off the mold to get the patio back to its regular color? I thought a bleach and water mixture would work, but I don't know the environmental ramifications (if any), and don't want to kill the grass which abuts the patio. —Katie, Chester Heights, Pennsylvania

A: Steve says : I had the same problem with my brick patio at my house here in the Boston area. I pressure washed the patio with plain water with a wide, low-pressure tip in the nozzle. It worked great and presented no challenge to the vegetation. An alternative would be to use one of the environmentally friendly, biodegradable patio washing products available at your local home center. But, if you're a tool junkie like me, this will give you an excuse to buy that pressure washer you've been looking for.
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