Amber trics in greenhouse.

Some strains never get amber trichomes and others can have 70%+ amber after only a few weeks of flowering and end up with 100% amber come harvest time - and this is why I believe basing harvest timing solely based on trichome colour can be misleading. Once your plant has 95-99% brown pistils, she is in the harvest window, with peak THC levels and moderate CBD levels. This also (generally) co-incides with the oft quoted "10-30% amber trichomes" zone, without having to look too closely and is far easier for newbies to understand. Once a plant has 100% brown pistils, death is approaching, with a corresponding drop in cannabinoid (THC) quality. If you prefer a THC influenced, clearer brain type of high, harvest when there are about 95-97% brown pistils. If you prefer a CBD influenced, heavier body type stone, harvest when there are about 97-99% brown pistils. Cold nights generally slow cannabinoid production and maturation and it is a fine line between leaving plants too long and harvesting good quality while you can. These are my opinions based on close to 40 years of outdoor cultivation experience and not ideas based on internet bro science. Hope this helps, Organoman.