Until recently, most herbal cannabis in the UK was
imported from Africa, the Far East and Caribbean,
however home-produced cannabis may now represent the
Imported cannabis appears in compressed blocks normally
bearing seeds, and would typically have a THC content
of 3-8%. Such material frequently appears in poor
condition with mould and decomposition present (accelerated
if damp - a potential risk for immuno-compromised
Home grown herbal cannabis falls into three basic
categories. "Hemp" is the fibre-producing
variety which can be cultivated under licence for
industrial uses, and would normally produce a THC
content of under 0.5% (although some long-established
cultivars, and individual plants, may produce higher
or lower THC contents), and a relatively high CBD:THC
Until recent years, most domestically produced cannabis
for drug content was derived from seeds in imported
"deals". THC content would be from 1% to
8%, similar to imported cannabis.
In the past decade, commercial seed developers based
in the Netherlands have developed a number of cultivars
(e.g. "Skunk", "Northern Lights"
and many others) suited for indoor growth by virtue
of short stature (internodal lengths), and early flowering.
THC contents are increased by preventing pollination
of female plants by males, leading to "sinsemilla"
- development of extensive flowering tops. The THC
contents of these varieties in ideal conditions vary
considerably, from around 5% to 15%, with exceptional
cases producing 20% THC. The cannabinoid spectrum
of these plants also varies. I am not aware of any
data available on the actual cannabinoid composition
of different varieties, although CBD levels tend to
be low or absent.
The THC contents associated with "Skunk"
cannabis should not be considered unusual, as similar
potencies were reported from some imported material
seized in the 1970s and 1980s. Furthermore, THC losses
in storage and transportation can render imported
cannabis significantly inferior to domestically-produced