How can you Test Cannabis THC strength?

There are test to determine the THC content in weed. THC is the main ingredient in weed that creats the high. However, test are complicated and require use of a lab. A general way to tell potency of weed is by looking at it. Higher consentration of THC will result in darker weed, 'crystals' on the weed itself, and increased odor and 'stickyness' to the weed, etc. while if looking for low THC amounts, look for many stems in the weed, etc.