The intensity of the blue hues varies considerably between different blue strains and the growing conditions are also an important factor in the level of colour. Plants that are exposed to slightly colder air in the later stages of their growth cycle tend to produce the most vivid blues.
The first blue strain that achieved wide commercial success was Blueberry, developed in the Netherlands in the late 1970s. Its reputation as a premiere weed was sealed in 2000, when it won first place in the High Times Cannabis Cup. Blueberry is an Indica dominant hybrid of plants from Thailand and Oaxaca in southern Mexico, and gives an intense, euphoric hit.
It's widely prescribed by medical cannabis dispensaries in the USA for muscular pain relief, stress and nausea. Blueberry Widow is another popular blue type and it's a crossbreeding of Blueberry and White Widow, both of which have been previous winners of the High Times Cannabis Cup. It gives a clear-headed stone with visual effects and, as the plant matures, the leaves and buds take on deepening shades of both blue and sometimes purple.
Blue Mystic is a highly respected strain from California and it's the product of crossing Blueberry with another venerable stalwart of the weed world, Northern Lights. It's a potent weed that gives a strong body stone combined with a powerfully narcotic high. The plants take on a noticeably blue colour as they start to flower, and the large buds have a velvety look.