Spec sheet first — strain: hybrid, seed type: feminized, THC: 16-20%, yield band: medium, environment: indoor or outdoor.

Lineage: Black Domina × Jack Herer, two strains that pull in opposite directions — one heavy and resinous, one bright and cerebral — and Blackjack lands somewhere useful in the middle. THC sits in the 16–20% range, which is enough to notice without making a trim day feel like a bad idea. Flowering wraps in 8–9 weeks, and growers running this indoors or out have recorded 400–500 g/m² when they keep feeding consistent through the stretch. The terpene profile skews citrus with an earthy backbone and a faint floral lift on the exhale — not a loud nose, but clean and pleasant in a cured jar.

Difficulty is rated moderate, so expect some attention to training; it responds well to LST if you want an even canopy. A good pick for anyone stepping past beginner strains who wants reliable yields without chasing a complicated phenotype.

Genetics & Lineage

Blackjack traces its genetics to Blackjack Feminized (Nirvana Seeds). This hybrid-dominant feminized seed produces plants that express the best traits of its parent lineage, delivering consistent results for growers of all experience levels. Bred by Nirvana Seeds, each seed is selected for genetic stability, terpene expression, and vigor.

Effects & Experience

Users report primarily relaxed and euphoric effects, making this strain ideal for evening use and unwinding after a long day. The body-centered stone builds gradually, easing tension and promoting deep physical relaxation. With THC levels reaching 20%, this offers a well-balanced experience suitable for most users with some cannabis familiarity.

THC Level & Potency

Blackjack delivers THC levels of 16-20%, placing it in the moderate-to-strong range that most regular consumers find comfortable. CBD content is minimal, so the psychoactive effects are front and center. The onset typically arrives within minutes with a balanced head-and-body experience that evolves over time.

Growing Blackjack

Blackjack is rated as moderate difficulty, making it suitable for growers with some experience. Basic knowledge of nutrient schedules, pH management, and environmental controls will help maximize results.

Indoor Growing: Expect a flowering time of 8-9 weeks with yields of 400-500g/m2. Plants typically reach 100-180cm indoors. Standard training techniques like topping and LST will help manage height and improve light penetration. Maintain temperatures between 68-80°F with relative humidity around 45-55% during flowering.

Outdoor Growing: This versatile strain performs well in both indoor and outdoor environments. Outdoor growers in warm climates can expect harvest from late September through October. Watch for humidity during late flowering to prevent bud rot, especially with dense flower formations.

Flavor, Aroma & Terpene Profile

Blackjack features a citrus, earthy, floral terpene profile that develops complexity throughout the flowering cycle. Bright lemon and orange zest punch through on the inhale, with a tangy, refreshing finish. The aroma intensifies significantly during the final 2-3 weeks of flowering — carbon filtration is recommended for indoor grows requiring discretion.

Medical Benefits

While individual experiences vary, Blackjack is commonly reported to help with stress relief, chronic pain, insomnia, and muscle tension. The deeply relaxing effects make it a popular choice among medical users seeking nighttime relief. As with any cannabis strain, start with a low dose and increase gradually. Consult a healthcare professional before using cannabis for medical purposes.

Who Should Grow Blackjack?

This strain is ideal for intermediate growers ready to push their skills and be rewarded with superior results. If you're looking for evening relaxation and deep stress relief, this is your strain.

Why Buy Blackjack from Seennabis?

When you purchase Blackjack through Seennabis, you are buying directly from Nirvana Seeds — One of Amsterdam's longest-running seed banks (since 1995). Every order includes verified genetics, discreet shipping, and responsive seller support.