Any well stocked, upscale garden center or agricultural supply house will have it. It will be in powdered form and comes in a small bag (like a 5# bag of sugar). Directions are on the bag; but again, always use the 'less is better than more approach'. The keywords with lowering pH are: Go Slow'. You don't have to do as I do, but just as an example only, on a new garden I use only one third to one half the recommended amount and add a little more each spring until I get the pH down where I want it. Keep in mind the pH change is not an instant reaction--it occurs slowly over a period of several days or even weeks. A good target pH for Asiatics and Orientals would about 6.5.
As a point of general interest to all readers is that NW15 resides in an area known as the old Knott's Berry Farm location, a name I sure most all of us have heard of at one time or another.
