Black JackStrain, Effects, Genetics, Grow Guide & Where to Buy
Black Jack is one of the most-searched cannabis strains in the United States, with a profile that holds up under scrutiny. It is a sativa-dominant (20% indica / 80% sativa) testing at roughly 23% THC, with a flowering window of 8-10 weeks under a 12/12 photoperiod. 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
No
Flowering
8-10 weeks
Difficulty
intermediate
Indoor Yield
450-550 g/m²
Outdoor Yield
500-700 g/plant
Plant Height
120-180 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 long-season outdoor zones, Southern California, Arizona, Texas, and Florida, where the extra 2-3 weeks of finishing time is available. Black Jack is photoperiod, which means you control when it flowers by switching from 18/6 (vegetative) to 12/12 (flowering). Most indoor growers veg for 4-6 weeks before the flip. Indoor yields land around 450-550 g/m² under quality LED, and outdoor plants given full sun and 5-7 gallon containers reliably produce 500-700 g/plant. Expected plant height is 120-180 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 defoliate strategically on day 21 of flower; remove fan leaves blocking interior bud sites without stripping the plant. The most common challenge growers report is over-feeding nitrogen past week 1 of flower, switch to bloom nutrients within 7 days of seeing pistils.
Black JackLineage & Genetics
Black Jack is a Royal King Genetics in-house cross. The parental selection was chosen for cerebral effects and aromatic complexity, then stabilized over multiple generations to lock in phenotype expression. Seeds run true to the description on this page rather than spreading across a wide range of expressions.
Where to Buy Black Jack Seeds in the USA
Black Jack seeds ship from Royal King Seeds to all 50 US states with discreet packaging and a 95% germination guarantee. Average delivery is 3-5 business days, with the fastest routes typically reaching Alaska, Arizona, Arkansas, California, Colorado.
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 8-10 weeks once you flip to 12/12 light cycle. Outdoor harvest typically lands in late September to mid-October across most US zones.
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. Photoperiod genetics give you control over plant size and harvest timing, which means a bit more responsibility for getting the schedule right. 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 to all 50 US states with discreet packaging, 3-5 day delivery, and a 95% germination guarantee. The product page is at https://royalkingseeds.us/black-jack-feminized, checkout accepts standard cards, Apple Pay, and crypto.