Sativa Dominant · Sensi Seeds
Jack Herer
Jack Herer is the Sensi Seeds release named after the American cannabis activist and author of The Emperor Wears No Clothes. The cross combines a Haze parent with Northern Lights #5 and Shiva Skunk to balance the long Haze flowering window against indica vigor. The strain has won more than a dozen Cannabis Cups in its various sub-phenotypes and has been a Dutch coffeeshop reference standard since the early 1990s. Plants finish in ten to eleven weeks indoors with pine-forward terpenes and an energetic, focused high that became the template for the modern uplifting-sativa category.
Reviewed 2026-05-23· Sources: seedfinder.eu, Sensi Seeds catalogue, Cannabis Cup archive
Potency
- THC range
- 18–24%
- Typical THC
- 21%
- CBD
- up to 0.2%
Flowering
- Indoor weeks
- 10–11 wk
- Difficulty
- Moderate
- Climate
- Mediterranean, warm temperate
Yield & size
- Indoor
- 450-550 g/m²
- Outdoor
- 500-700 g/plant
- Height
- 140-180 cm
Indica / sativa ratio
Terpene profile
The aromatic compounds below shape how Jack Herer smells, tastes, and ultimately feels in the body.
- dominant
Terpinolene
Piney and fruity — fresh, slightly floral, common in sativa-leaning cultivars.
- secondary
Pinene
Alert and pine-forward — associated with mental clarity and bronchodilation.
- secondary
Caryophyllene
Peppery and spicy — the only terpene that binds CB2 receptors, studied for anti-inflammatory action.
- minor
Ocimene
Sweet and herbal — light, tropical, with a decongestant character.
Reported side effects
Lineage
Jack Herer traces to Haze × Northern Lights #5 × Shiva Skunk. The cross sits in the Haze family, which influences both the terpene profile and the flowering structure described above.
Genetic family tree
Documented parents for Jack Herer based on breeder catalogues. Library entries are clickable; ancestors not yet documented on this site appear in a lighter, non-linked box.
Strains crossed with Jack Herer
Jack Herer is a parent of 4 strains in the broader catalogue. These are crosses that carry Jack Herer genetics on at least one side of the cross.
Grow profile
Grow profile
- Indica / sativa
- 45% / 55%
- Flowering days
- 70–77 days
- Stretch
- High
- Pest resistance
- High
- Mold resistance
- Moderate
- Training methods
- topping, scrog, supercropping
Feed schedule for Jack Herer
These EC and NPK targets are starting points calibrated for the strain's Sativa lean and moderate difficulty rating — not gospel. Drop 15-20% off any EC ceiling on your first run and let the plant tell you where it actually wants to feed.
Suggested feed schedule
- Late veg
- 1.2-1.4 EC
- Early flower
- 1.3-1.5 EC, NPK 2-2-3
- Mid flower
- 1.6-1.8 EC, NPK 1-3-4
- Late flower
- 1.4-1.6 EC
- Final week
- Plain pH-balanced water for the last 7-10 days; light flush if you ran nutrients on the higher end.
Full breakdown of feed math, runoff testing, and salt buildup in our nutrient guide.
What to expect through the grow cycle
Jack Herer is documented with a 11-week flower and a longer stretch phase typical of sativa-leaning hybrids. The visual below maps a documented 15-week cycle built from 4weeks of vegetative growth and the strain's published flowering window.
Published grow reports for Jack Herer concentrate the most observational notes on the stretch window. This timeline is descriptive — it reflects what reports document, not a how-to. Actual week-to-week behaviour varies with phenotype, light intensity, pot size, and environment.
Phase details
- Veg (weeks 1-4)
- The documented vegetative period for Jack Herer. Plants establish root structure, leaf canopy, and node count before flower triggering, with a moderate difficulty rating shaping how forgiving the early canopy work tends to be.
- Stretch (weeks 5-8)
- Jack Herer is documented as having high stretch. Reports describe the plant roughly doubling in height during this phase as the sativa-leaning structure establishes its final flowering frame.
- Bud sites (weeks 9-10)
- Pre-flowers form at the nodes and calyxes begin to develop. Grow reports for Jack Herernote this as the window where the canopy's eventual bud distribution becomes visible.
- Bud development (weeks 11-13)
- Flowers thicken and calyxes fatten through this phase. Documented Jack Herer runs show the bulk of visible flower mass accumulating here, with resin production accelerating toward the end.
- Ripening (week 14)
- Trichomes transition from clear toward cloudy and amber. Reports for Jack Herer describe the Terpinolene-led terpene profile maturing through this window, with aroma sharpening week over week.
- Final (week 15)
- Calyx swelling is documented as complete and the harvest window opens. Published Jack Herer runs end here, within the 10-11 week flowering range reported by the breeder.
Flavor & aroma
Reported effects
Awards
- 1994 · High Times Cannabis Cup — 1st (Coffeeshop)
- 1999 · High Times Cannabis Cup — 1st (Hydro)
Common questions about Jack Herer
Is Jack Herer a true sativa?
It is sativa-dominant rather than pure sativa. The Northern Lights side cuts the flowering window down from the 14+ weeks a pure Haze would need to about ten.
Why are there so many Jack Herer phenotypes?
Sensi released regular (non-feminized) seed for years, and the three-parent cross produced wide phenotype variation. Breeders selected favorites and stabilized them as separate strains like Jack Flash and J1.
Breeder of record
Sensi Seeds
View breeder profile and other strains →
More from Sensi Seeds
Strains similar to Jack Herer
These picks lean on the same terpene profile and parent genetics as Jack Herer — shared dominant terps, overlapping lineage, and matching indica/sativa lean. No star ratings or popularity contests, just overlap on the traits that actually drive a similar grow and smoke.
