Jack Flash

Sensi Seeds combined three lines in Jack Flash: its in-house Jack Herer, Super Skunk and a Haze. The sources do not agree on how the parents were joined. One strain description gives the formula Jack Herer × (Super Skunk × Haze), another names Jack Herer as the mother plant, while the pedigree of the feminized Jack Flash #5 lists only Jack Herer and Super Skunk. On classification, Sensi Seeds puts the regular Jack Flash at 55 % indica and 45 % sativa and Jack Flash #5 at 65 % indica and 35 % sativa; other descriptions list the strain as sativa-dominant.

Genetics and Origin:

According to strain descriptions, the breeder wanted to preserve the effect of Jack Herer while increasing yield and vigor. At the High Times Cannabis Cup 2004 in Amsterdam, Jack Flash took 3rd place in the overall ranking behind Amnesia Haze and Killer Green, and at the Highlife Cup 2007 it placed 3rd in the Hydro category according to Sensi Seeds.

The strain is documented as a parent in several crosses. The Bank Genetics crossed a Jack Flash mother with Afghan Ghost OG for Ghost Jack, Django traces back to Blueberry and Jack Flash, and Big Nose Genetics used Jack Flash #5 together with Limon Picon for Jack and Limon.

Aroma and Flavor:

Sensi Seeds describes the scent of the regular version as skunky and pungent; toward the end of flowering it becomes more intense and mustier. For flavor, the breeder lists citrus and exotic wood, and for Jack Flash #5 pine with citrus and earthy undertones. Earthy citrus notes over a skunk undertone also appear in another strain description. One reviewer picked up lemon and skunk in the aroma and tasted a slightly nutty pine note. In the breeder's grow report, the plant smelled sweet, of berries and floral during flowering, with a note of Sour Diesel underneath.

Effects:

User reports center on a fast-onset effect in the head. Consumers describe themselves as energetic and euphoric, some also as sociable and silly, others as creative or focused. A few mention a light bodily relaxation that cushions the head effect. Not all reports fit this picture: occasionally the strain was sedating to sleepy, in one case the initial stimulation was followed by fatigue and dizziness, and one consumer complained that the effect faded quickly. Sensi Seeds describes the effect as euphoric and stimulating, combined with talkativeness, and for Jack Flash #5 mentions a mild psychedelic component.

Strain descriptions list dry mouth, dry eyes and headaches as side effects, one of them also anxiety, paranoia and a racing heart at high doses. One reviewer found the smoke harsh and had to cough.

Lab Results:

One lab value exists as a single measurement. Digipath Labs determined 20.1 % THC (THC and THCA combined) and 0.032 % CBD in a sample in 2017, a clearly THC-dominant ratio, plus 0.837 % CBG and 0.127 % CBN. In the terpene profile of the same sample, γ-terpinene at 0.438 % ranked ahead of terpinolene at 0.314 % and myrcene at 0.145 %. One strain description lists terpinolene as the dominant terpene, followed by myrcene and caryophyllene.

Further THC figures come from grow and user reports: 17.8 % is given for the plant in Sensi Seeds' grow report, 20.25 % for a sample reviewed in 2016. One strain description puts it at 17 %.

Cultivation:

For the regular Jack Flash, Sensi Seeds gives a flowering time of about 70 days, for Jack Flash #5 55 to 75 days. The breeder puts yields of the regular version at around 500 g/m² indoors and around 600 g per plant outdoors, and for Jack Flash #5 likewise at around 600 g per plant outdoors. As climate, Sensi Seeds names warm, sunny regions with a long summer; one strain profile, by contrast, envisions Jack Flash for indoor cultivation only. On difficulty the sources disagree: the breeder's current description calls the strain easy to grow, though pruning requires know-how, while a text published in 2011 still advised beginners against it. As training methods the breeder lists supercropping and lollipopping.

According to Sensi Seeds, 2 phenotypes arise from seed. The stocky type forms large flowers and stays at about 100 cm, while the slender one with thin side shoots reaches up to 180 cm indoors. Outdoors the breeder gives 180 to 250 cm.

Documented grows show how much the plants can grow during flowering. One Jack Flash #5 grew indoors from about 35 to 125 cm and was ripe after 70 days of flowering; the grower describes hard, compact flowers, a high fertilizer demand and a good response to SCROG, with the shoots needing supports. In another report a regular plant went from 50 to 80 cm after 73 days of flowering, grew in a fir-tree shape, formed somewhat loose flowers and got by with little fertilizer. It was not prone to mold but reacted sensitively to low temperatures. A buyer, by contrast, warned of mold in the dense flowers toward the end of flowering.

In Sensi Seeds' grow report from 2026, a regular plant stood under a 1000-watt sodium vapor lamp. After 34 days of growth and 64 days of flowering it measured 147 cm; long internodes stood out, and the flowers became so dense and heavy that the branches had to be supported. The harvest was 132 g of dried flowers. Outdoors, a grower in Northern California harvested in the first week of October.