Here's the PFAF page on Rubus occidentalis. Has leaf uses listed.

FataMorgana

Here is a link that might be useful: Pfaf.org - Rubus occidentalis

they both exhibit astringent properties, raspberry has other wonderful properties as well (is nutritive for example) but blackberry could be used in a pinch for the astringency if needed...say for bleeding or upset tummy.

So I just pick the young leaves & dry them?
Or are any age leaf good?
Do I add them to other teas or add other leaves to the dried raspberry leaves?
I have hundred of the red raspberry plants.

I pick as the need and leaf are there. I'm sure there are others who will say specific times are required.

You'll want good quality, healthy leaves. Skip the old, "tired" looking leaves. Dry them. Use for tea by themselves or in combination with other herbs, as needed.

FataMorgana

I have more then I can use,so I can use & dry the young tender leaves.
If any of you are in S.C. & would like some plants, email me.