Downward-Draining Herbs

What special cooking instruction should be following when using Huo Ma Ren (cannabis semen) in decoction?

Huo Ma Ren is a seed with a strong outer shell. It must be crushed first in order to access its oils.

Source: Bensky, D. (2004). Chinese Herbal Medicine: Materia Medica. Seattle, WA: Eastland Press. p. 245 [Q812]