The Official Cannabis Independent strain guides
Critical Jack No 10 Shop
The Strain Deck · Three of ClubsNo 10 · Critical Jackcriticaljack.com
Critical Jack stamp, No. 10 in the Official Cannabis collection: an exclamation mark on a yellow burst, on rust red

Catalogue entry · lab-tested · every claim cited

Critical Jack strain

Critical Jack is a sativa-leaning hybrid of Critical+ and Jack Herer bred by Dinafem Seeds of San Sebastián, in Spain’s Basque Country.1,2,3,4,5 It tests at a median total THC of 15.01% across 8 state lab tests of Critical Jack flower, with the middle half of results between 13.41% and 20.68%: only eight tests, far too few to show a typical range.6 Leafly lists focused, energetic and uplifted as its top effects, from user reports.7

Updated 8 lab tests 23 sources

Design
An exclamation mark on a yellow burst, on rust red · No 10 in the collection
In the Strain Deck
Three of Clubs · Classics suit
Type
Sativa-leaning hybrid; Dinafem lists 60% sativa / 40% indica, Leafly and Weedmaps say hybrid1,3,7
Parents
Critical+ × Jack Herer (AllBud alone says Critical Mass)1,2,8
Origin
Dinafem Seeds, San Sebastián, Spain; on sale by 2015 (no release year published)1,3,4
THC (lab tests)
15.01% median; 13.41%–20.68% middle half; only eight tests, a small sample, from 2 states6
CBD (lab tests)
Low: 2 of the 4 tests that reported CBD found none, none reached 1%, and the highest was 0.20%6
Terpenes (lab tests)
Too few tests for a profile: only one of the eight tests reported individual terpene values6
Flavor (most reported)
Pine, citrus, lemon; Dinafem adds wood, incense and spices1,7
Effects (Leafly’s top three)
Focused, energetic, uplifted7
Flowering time
60 days indoors in Dinafem’s spec; Leafly says around day 601,7

The guide one plate per section

Plate I

Genetics

Critical Jack is Dinafem’s Critical+ (Big Bud × Skunk) × Sensi Seeds’ Jack Herer. Where Critical+ comes from, how sativa it is, and the other Critical Jacks.

Plate II

THC & terpenes

Critical Jack tested at 15.01% median THC in only eight US lab tests from Massachusetts and Michigan: a very small sample. Breeder figures, CBD and caveats.

Plate III

Effects

Leafly’s top effects for Critical Jack are focused, energetic and uplifted; breeders call it cerebral and long-lasting. Downsides: anxious, dry mouth, dry eyes.

Plate IV

Grow

Critical Jack flowers in about 60 days indoors and finishes outdoors from late September; Dinafem claims 625 g/m² and 3 m plants. Breeder specs side by side.

Plate V

Where to find it

Critical Jack flower is scarce in US stores: 2 Weedmaps listings in 1 of 27 markets on Oct 3, 2026. Store counts by market and the European seed trade.

Plate VI

History

How a Basque seed bank crossed Critical+ with Jack Herer, won cups, was shut down by a 2020 police operation and saw its genetics move to Rotterdam.

Quick answers

Is Critical Jack indica or sativa?

A sativa-leaning hybrid. Dinafem’s genotype field reads 40% indica / 60% sativa, Silent Seeds and AllBud repeat 60% sativa, Wikileaf says 55%, and Leafly and Weedmaps simply file it as a hybrid. SeedFinder’s grow reports describe two phenotypes, one long and sativa-like, one short and compact.1,3,7,8,9,10,11

How strong is Critical Jack?

Our only measurements come from a very small sample: only eight tests, with a median total THC of 15.01% and none reaching 25%.6 Dinafem lists 15–20% THC for its seeds and Leafly and AllBud publish 20%.1,7,8

Is Critical Jack the same as Jack Herer or Critical Jack Herer?

No. Jack Herer is one of its two parents. Leafly lists "Critical Jack Herer" as another name for Critical Jack, but Delicious Seeds of Valencia sells a different cross under that name, Critical Mass × Jack Herer.2,7,12

What does Critical Jack taste like?

Lemon and pine. Leafly users list pine, citrus and lemon; Dinafem describes "a sweet and intense taste that mixes hints of wood, incense, pine, spices and lemon"; AllBud adds a spicy pepper aroma.1,7,8

Who bred Critical Jack, and do they still sell it?

Dinafem Seeds, founded in 2005 in San Sebastián. Its catalogue is still online but every page says it does not currently sell seeds, after Spanish authorities intervened in the company in September 2020. Silent Seeds, which calls itself Dinafem’s sole heir, sells a Critical Jack it says comes from the same clones.1,13,14,15,16

Where is Critical Jack sold?

Rarely in US stores. On Oct 3, 2026, Weedmaps showed Critical Jack flower at 2 store listings in 1 of 27 US markets, all within 50 miles of Detroit; the other 26 markets, including Los Angeles, Denver and New York, had none.17 In Europe it circulates as seeds: Silent Seeds (Rotterdam) and, as Critical Jack Herer, Delicious Seeds (Valencia) list it.15,18

How strong Critical Jack tests

15.01%median total THC (small sample)
13.41%–20.68%middle half of tests
8lab tests, 2 states
2testing labs

THC in 8 lab tests of Critical Jack flower

0 10 6–7% THC: 0 tests 7–8% THC: 1 tests 8–9% THC: 0 tests 9–10% THC: 0 tests 10–11% THC: 0 tests 11–12% THC: 1 tests 12–13% THC: 0 tests 13–14% THC: 0 tests 14–15% THC: 2 tests 15–16% THC: 1 tests 16–17% THC: 0 tests 17–18% THC: 0 tests 18–19% THC: 0 tests 19–20% THC: 0 tests 20–21% THC: 1 tests 21–22% THC: 2 tests 22–23% THC: 0 tests 23–24% THC: 0 tests 24–25% THC: 0 tests 25–26% THC: 0 tests 26–27% THC: 0 tests 27–28% THC: 0 tests 28–29% THC: 0 tests 29–30% THC: 0 tests 30–31% THC: 0 tests 31–32% THC: 0 tests 32–33% THC: 0 tests 33–34% THC: 0 tests 8%12%16%20%24%28%32% median 15.01% Total THC, % by weight
Each bar counts tests in a one-point THC band; the shaded band is the middle half of results. 8 tests of Critical Jack flower from 2 states, 2016–2022. Small sample: treat as indicative.6

Full lab data: by year, by state, terpenes and the downloadable dataset →

From the lab report

  • This small sample of 8 tests leaves Critical Jack unranked; median total THC was 15.01% and the share at 25% was 0%.6
  • Critical Jack reached 20% total THC or higher in 38% of flower tests; the shares at 25% and 30% were 0% and 0%.6
  • The 20% published single figure from Leafly was reached by 38% of Critical Jack tests, about 4 in 10.6,7

Read the full Critical Jack lab report →

Cup wins in Spain’s orbit, a thin footprint in US stores

Critical Jack’s record is a breeder’s record. Dinafem reports first prizes for Best Shatter at the 2015 San Bernardino Hempcon Cup, for Outdoor Sativa at the 2016 UCLA cup (Unión Cannábica Latinoamericana) and for Outdoor at the V Copa Cata Zona Norte in Buenos Aires in September 2019; Weedmaps and Wikileaf repeat the first two.1,2,3,10 Its Leafly page has 181 ratings, AllBud’s 11 votes, and Dinafem’s own page 120 customer reviews; GrowDiaries holds 25 grow diaries of the Dinafem line.1,7,8,19

It does not appear in the US sales rankings we checked, Leafly’s best-selling strains of 2025 and The Marijuana Herald’s September 2026 list of top sellers by state.20,21 On Oct 3, 2026, Weedmaps showed Critical Jack flower at 2 store listings in 1 of 27 US markets, all within 50 miles of Detroit; the other 26 markets, including Los Angeles, Denver and New York, had none.17 Wikileaf calls it "widely popular throughout California and much of the West Coast"; our lab dataset holds only eight tests under the exact name, none from California.6,10

Critical Jack next to similar strains

Lab-tested THC: Critical Jack and the 6 strains on our comparison pages

12% 16% 20% 24% Sour Diesel Sour Diesel: median 21.68%, middle half 19.00%–25.30%, 1,071 tests 21.7% n=1,071 Super Lemon Haze Super Lemon Haze: median 20.84%, middle half 18.41%–23.48%, 1,543 tests 20.8% n=1,543 G13 Haze G13 Haze: median 20.30%, middle half 19.98%–21.86%, 14 tests 20.3% n=14 Blue Dream Blue Dream: median 19.96%, middle half 17.62%–22.37%, 2,118 tests 20.0% n=2,118 Jack Herer Jack Herer: median 19.59%, middle half 17.13%–22.00%, 910 tests 19.6% n=910 Durban Poison Durban Poison: median 19.45%, middle half 17.33%–21.99%, 528 tests 19.4% n=528 Critical Jack Critical Jack: median 15.01%, middle half 13.41%–20.68%, 8 tests 15.0% n=8 Median total THC (dot) and middle half of tests (bar)
Same state lab dataset and matching rules for every strain.6 See the comparisons.

Where it is sold

MarketStoresMenu itemsMedian eighth
Detroit, MI 2 2 —
Anchorage, AK 0 0 —
Phoenix, AZ 0 0 —
Los Angeles, CA 0 0 —
Denver, CO 0 0 —
Hartford, CT 0 0 —

Stores within 50 miles listing Critical Jack flower on Weedmaps, Oct 3, 2026.17

All 27 markets, Germany and how we counted →

Genetics at a glance

Family tree

  • Critical+ (Dinafem)Big Bud × Skunk per Dinafem; released 2005; a Critical Mass selection per SeedFinder
  • Jack Herer (Sensi Seeds)Haze hybrid × Northern Lights #5 × Shiva Skunk; Netherlands, mid-1990s

Critical Jack

  • Pai GowSuper Silver Haze × Critical Jack
  • Baccarat (Symbiotic Genetics)Bred from Critical Jack (SeedFinder)
  • Birrie Jack (Amaranta Seeds)Bred from Critical Jack (SeedFinder)
  • Killer Critical Jack (MadCat’s Backyard Stash)Bred from Critical Jack (SeedFinder)
  • Critical Jack (Fatbush Seeds)Bred from Critical Jack (SeedFinder)
  • Critical Jack Autoflowering (Growers Choice)Bred from Critical Jack (SeedFinder)
Parents as stated by Dinafem; offspring as listed by Leafly and SeedFinder.1,22,23

Where Critical+ comes from, how many Critical Jacks there are: the full genetics page →

The issue printed on demand, nothing on sale yet

The whole issue →

Sources

  1. Dinafem Seeds, Critical Jack: feminized seeds, specifications, lab analysis and awards. Accessed Oct 3, 2026.
  2. Dinafem Seeds, Critical Jack feminised marijuana strain (Dinafem TV). Accessed Oct 3, 2026.
  3. Weedmaps, Critical Jack strain page. Accessed Oct 3, 2026.
  4. Dinafem Seeds, Dinafem Seeds (home page: company address and seed-sales notice). Accessed Oct 3, 2026.
  5. Cáñamo, La policía interviene el banco de semillas Dinafem (2020-11-01). Accessed Oct 3, 2026.
  6. Cannlytics (CC BY 4.0), cannabis_results: public state lab results (filtered and aggregated by Official Cannabis). Accessed Oct 3, 2026.
  7. Leafly, Critical Jack aka Critical Jack Herer strain information. Accessed Oct 3, 2026.
  8. AllBud, Critical Jack marijuana strain information and reviews. Accessed Oct 3, 2026.
  9. Silent Seeds, Critical Jack feminized seeds. Accessed Oct 3, 2026.
  10. Wikileaf, Critical Jack strain. Accessed Oct 3, 2026.
  11. SeedFinder, Critical Jack (Dinafem): strain info, breeder description and grow reports. Accessed Oct 3, 2026.
  12. Delicious Seeds, Critical Jack Herer feminized seeds. Accessed Oct 3, 2026.
  13. High Times, An interview with Dinafem Seeds: Europe’s king of feminized seeds (Stoney Tark) (2019-03-14). Accessed Oct 3, 2026.
  14. Público, La intervención judicial de uno de los mayores bancos de semillas de cannabis causa perplejidad en el sector (Santiago F. Reviejo) (2020-10-12). Accessed Oct 3, 2026.
  15. Silent Seeds, Silent Seeds, the sole heir to Dinafem Seeds (home page). Accessed Oct 3, 2026.
  16. SeedFinder, Critical Jack (Silent Seeds): strain info. Accessed Oct 3, 2026.
  17. Weedmaps listings, compiled by Official Cannabis, Weedmaps flower menu snapshot, 27 US markets, Oct 3, 2026. Accessed Oct 3, 2026. Latest capture Oct 3, 2026.
  18. Delicious Seeds, Delicious Seeds (home page: company address). Accessed Oct 3, 2026.
  19. GrowDiaries, Critical Jack (Dinafem): grow diaries and harvest reviews. Accessed Oct 3, 2026.
  20. Leafly, The best-selling weed strains of 2025 (2026-02-02). Accessed Oct 3, 2026.
  21. The Marijuana Herald, The top-selling marijuana strain in all 23 states with legal recreational sales (2026-09-18). Accessed Oct 3, 2026.
  22. Leafly, Pai Gow strain information. Accessed Oct 3, 2026.
  23. SeedFinder, Critical Jack (Dinafem): genealogy and hybrids. Accessed Oct 3, 2026.