by clicking through to the higher res views you might note that there are some structural issues there: the posts at the bottom and the stair treads are rotting, there's a general slope downwards to the right, and some other issues going on in the upper woodwork. 

the property owner has scheduled that porch for a rebuild; the work should get underway within the next few days if it hasn't started already.  it will be interesting to see how it comes out.  as a practicing architect and chairman of the Grove's Historic Preservation Commission he certainly knows this stuff. 

so the row of yellow lilies?  I would imagine they are intended to discourage anyone from going up or down those stairs until the work is done.