I don't know what your climate is, but in my climate this doesn't seem to be a problem. Our siding is 100 years old and has probably had plant contact for a good portion of that time. But trimming it away certainly wouldn't hurt the plant or the siding.

Managing the pachysandra in the long term may require you to thin it periodically by taking out chunks of its root mass to give it new room to grow. I don't know pachysandra that well, but based on other ground covers... If it is doing really well, and it sounds like it is, and is in a confined area, it may eventually choke on itself, some will die off, and it will rejuvenate itself over time, thus going through cycles. You could just watch how dense it is and be a bit proactive if it gets really thick.

KarinL

Thanks, yes the plants are doing very well, and crowded. I have to keep mowing close to the intended edge to keep if from taking over the lawn.

I have pulled some plants to spread to other areas. That seems to be growing well in its new location. I didn't take much care either, just pulled up some chunks and scratched the surface where I transplanted to.

This plant is a colonizer, so it isn't suitable everywhere - it's no sin to discard excess of it instead of transplanting it. I personally don't put plants like this where there isn't a physical barrier keeping them corralled, but if you can maintain the edge with mowing, that's good.

KarinL