pH of worm castings?

Do worm castings have the same pH range regardless of the type of soil they live in, or does it vary? My soil is heavy clay which must be acidic because moss grows on it willingly.

My understanding is that Worm castings are PH neutral and will bring the soil it is added to neutral as well. Merry Christmas!

In Charlotte, the clay is typically slightly acidic, but this is not the main reason that moss will grow.
Moss will grow on constantly moist surfaces where other plants have difficulty growing. If the soil is sufficiently loose to support other plant forms, they will almost always compete well against moss which is very primitive and have difficulty competing. Only on surfaces where other plants have difficulty growing, can moss take hold. The hard, compact nature of clay is one such surface. Secondly, since clay holds moisture well, it is a good foundation for moss, especially if the sun does not reach the area directly and dries out the surface.

If you want to improve soil conditions to grow other plants, or grass, instead of moss I recommend following:
1) loosen the clay and mix in organic matter, such as compost (you can use the worm castings, but other forms include shredded leaves, composted bark, or home made compost from a compost pile). Mixing in organic matter liberally (20-30% by volume) will help break up the structure of the clay and allow deeper rooted plants to compete with the moss.

2) try to allow sufficient sunlight into the area. If shaded by structures or low hanging limbs, try to move structures or prune branches. The best defense against moss is to allow direct sunlight.

I.e. you do not have to focus so closely on the pH value as it is really not critical in this connection. Moss can be found on alkaline hard clay soil in the shade, and other plants, such as grass, will grow well in slightly acidic soils. Just amending the soil for pH value will not be enough.

Your best bet is to amend the soil to loosen the structures by incorporating (tilling) in organic matter 20-30% by volume. Also try to allow more direct sunlight, if possible.

I hope the above was helpful to you.
-- Kenneth

Thanks for your answer, Kenneth. I didn't realize moss would grow in all types of soils. Actually, I kinda like seeing moss growing between the flagstones and in other areas where I have nothing growing (too shady). Sometimes I move moss from areas where I don't want it, to areas where it's more welcome.