Black JackStrain, Effects, Genetics, Grow Guide & Where to Buy
Black Jack is one of the most-searched cannabis strains in the United States, but the data behind the hype is what holds growers' attention. It is a sativa-dominant (20% indica / 80% sativa) testing at roughly 23% THC, with a flowering window of 9 weeks from germination as an autoflower. This guide pulls together the lineage, the effects, the grow data, and the practical answer to "where can I buy Black Jack seeds in the USA" in one place.
Black Jack Quick Stats
THC
23%
Indica
20%
Sativa
80%
Autoflower
Yes
Flowering
9 weeks from germination
Difficulty
intermediate
Indoor Yield
400-550 g/m2
Outdoor Yield
40-250 g/plant
Plant Height
40-110 cm
Black JackEffects & Experience
Reported effects center on euphoric, focused, energetic. Black Jack pulls toward mental clarity, conversation, and a light, mobile body feel, a profile that holds up across phenotypes when the seeds are grown to their potential.
Growing Black Jack
Growing Black Jack fits short outdoor seasons in the upper Midwest, Pacific Northwest, and Northeast, autoflower genetics finish in 70-90 days from seed regardless of latitude. Black Jack runs on an 18/6 light schedule from seed to harvest, autoflower genetics ignore photoperiod, so there is no flip and no light-cycle change. Indoor yields land around 400-550 g/m2 under quality LED, and outdoor plants given full sun and 5-7 gallon containers reliably produce 40-250 g/plant. Expected plant height is 40-110 cm, with intermediate cultivation difficulty. Practical tips that move the needle: apply low-stress training in week 2 of veg, bend the main stem horizontally and tie down to expose lower nodes; and top once at the 4th node to encourage 4-6 even main colas instead of one dominant cola. The most common challenge growers report is calcium and magnesium supplementation under bright LED lighting; cal-mag at 2-3 mL/gal from week 2 prevents the most common deficiency.
Black JackLineage & Genetics
Black Jack is offered in the Royal King Seeds catalog. Read the description on this page as a general profile rather than a guarantee of your specific pack; expect some phenotype variation between packs.
Where to Buy Black Jack Seeds in the USA
Black Jack seeds ship from Royal King Seeds from within the United States. Estimated delivery is approximately 5-7 business days; actual timing varies by destination and carrier.
Black Jack FAQ
Is Black Jack indica or sativa?+
Black Jack is a sativa-dominant with a 20% indica / 80% sativa split. The effects lean toward mental clarity, mood lift, and conversation.
How long does Black Jack take to flower?+
Black Jack flowers in 9 weeks from germination from seed, since autoflower genetics ignore light cycle. Outdoor harvest typically lands 70-90 days after planting.
What is the THC content of Black Jack?+
Black Jack tests at approximately 23% THC when grown to its potential. Real-world numbers depend on grow conditions, harvest timing, and curing, well-grown phenotypes can land at the high end of that range, while poorly cured flower tests lower.
Is Black Jack good for beginner growers?+
Black Jack is rated intermediate difficulty. The autoflower genetics simplify the process, no light schedule changes and a fast seed-to-harvest timeline make it forgiving for first-time growers. Most growers with one harvest behind them handle this strain without difficulty.
Where can I buy Black Jack seeds in the USA?+
Royal King Seeds ships Black Jack seeds from within the United States, with estimated delivery in approximately 5-7 business days. The product page is at https://royalkingseeds.us/black-jack-auto.