Question
Moss growth on my brick patio (on concrete slab on grade) keeps me power washing it off and it only makes the hand made brick more porous. How can I kill the moss for extended periods of time?

Answer
David, chemicals are your only option given the fact the moss is on your patio. In the garden, I usually recommend an organic method such as solarization. This would not be practical on a patio.

Roundup is a general herbicide that will kill any vegetation to which it is applied. Roundup should not be used near the vegetable garden or flower beds. However, like all chemicals, it slowly dissipates and eventually breaks down to a point where it is no longer dangerous. Most experts argue that the period between application and safe planting is anywhere from one to three months. As long as you're careful when you spray, you should have no problems.

Good luck, and please write again if I can ever be of assistance.

Regards,

Mike