The Official Cannabis Independent strain guides
Critical Jack No 10 Shop
The Official Cannabis collection · sheet 10No 10 · Critical JackGrow

Growing

Growing Critical Jack: flowering time, yield and breeder specs

Dinafem’s feminized Critical Jack flowers in 60 days indoors, finishes outdoors from late September to mid-October and, the breeder says, yields 625 g/m² indoors and up to 1200 g from a 3 m plant outside; Leafly and Wikileaf give about 60 days too.1,2,3 The autoflowering lines sold under the name are different crosses with their own figures.4,5

Breeder specs side by side

Source and versionFloweringIndoor yieldOutdoorDifficulty
Dinafem, feminized (Critical+ × Jack Herer)60 days625 g/m²Late September to mid-October; 1200 g/plant; 3 m1—
Silent Seeds, feminized (same cross; "same clones" per SeedFinder)60 days625 g/m²Late September to early October; 1,200 g/plant; 3 m6,7—
Dinafem, Critical Jack Autoflowering (Critical+ 2.0 × Haze 2.0 Auto)70–80 days whole cycle25–100 g/plant100–230 g/plant; 0.5–1 m4—
Delicious Seeds, Critical Jack Herer (Critical Mass × Jack Herer)60 to 70 days500 g/m²Mid-October; 900 g/plant; XL height8—
Delicious Seeds, Critical Jack Herer Auto (Critical Mass Auto × Jack Herer Auto)60–70 days whole cycle500 g/m²More than 80 g/plant5High mold and pest resistance claimed5
Leafly (strain page)Around day 60—Late September to early October2Mildew resistant; top early, lollipop2
Wikileaf57–67 days"Well above average"Late September to early October3—

Seed-company figures are the sellers’ own claims.

What the plant is like

Expect an open, branchy plant that can reach 3 m outdoors, with "large, thick, rock-hard buds covered in a dense layer of trichomes", in Dinafem’s words; Weedmaps gives a 63-day flowering period and the same open structure, and SeedFinder 55–65 days with two phenotypes, one stretched and one compact.1,9,10 Leafly suggests topping early for a bushier plant and lollipopping for dense, stacked buds.2

On GrowDiaries, 13 harvests of the Dinafem line average 66 g per plant, a grower-reported figure that is not comparable with the breeder’s per-square-metre or outdoor claims.11 Dinafem recommends dry, sunny, temperate Mediterranean climates and says the plant does best outdoors or in a greenhouse.1

What to watch for

Damp. Dinafem says Critical Jack "copes well with insect and moisture attacks, even when there is constant rain", and Leafly calls it mildew resistant, but the Critical side of the family has a reputation to manage: Leafly describes Critical Mass, which SeedFinder places in Critical Jack’s ancestry, as "particularly susceptible to mold", with branches that snap under the weight of its buds, and Dinafem itself reworked Critical+ into Critical+ 2.0 by crossing in "a moisture-resistant phenotype".1,2,12,13,14

Seeds and the law in the US

Under the amended federal definition of hemp, viable seeds from cannabis plants above 0.3% total THC, including THCA, are not hemp.15 Congress delayed that exclusion, with most of the new definition, from Nov 12 to Dec 11, 2026; only the exclusion of products with cannabinoids the plant cannot produce naturally starts on Nov 12.16 Home cultivation rules are set by each state. This site does not sell seeds.

Seeds and the law in Spain

Critical Jack comes from a country where seed banks traded openly. Público reports that Spanish seed companies relied on the UN’s 1961 Single Convention, which leaves cannabis seeds outside drug control, and on a 2003 report by the Supreme Court prosecutor’s office that confirmed that reading in the absence of specific Spanish law.17 That position was tested in September 2020, when the Guardia Civil intervened in Dinafem’s parent company on allegations the company denied (see history).17,18 This site does not sell seeds.

Sources

  1. Dinafem Seeds, Critical Jack: feminized seeds, specifications, lab analysis and awards. Accessed Oct 3, 2026.
  2. Leafly, Critical Jack aka Critical Jack Herer strain information. Accessed Oct 3, 2026.
  3. Wikileaf, Critical Jack strain. Accessed Oct 3, 2026.
  4. Dinafem Seeds, Critical Jack Autoflowering. Accessed Oct 3, 2026.
  5. Delicious Seeds, Critical Jack Herer Auto. Accessed Oct 3, 2026.
  6. Silent Seeds, Critical Jack feminized seeds. Accessed Oct 3, 2026.
  7. SeedFinder, Critical Jack (Silent Seeds): strain info. Accessed Oct 3, 2026.
  8. Delicious Seeds, Critical Jack Herer feminized seeds. Accessed Oct 3, 2026.
  9. Weedmaps, Critical Jack strain page. Accessed Oct 3, 2026.
  10. SeedFinder, Critical Jack (Dinafem): strain info, breeder description and grow reports. Accessed Oct 3, 2026.
  11. GrowDiaries, Critical Jack (Dinafem): grow diaries and harvest reviews. Accessed Oct 3, 2026.
  12. Leafly, Critical Mass strain information. Accessed Oct 3, 2026.
  13. SeedFinder, Critical Jack (Dinafem): genealogy and hybrids. Accessed Oct 3, 2026.
  14. Dinafem Seeds, Critical+ 2.0 feminized seeds. Accessed Oct 3, 2026.
  15. Congressional Research Service, Changes to the statutory definition of hemp and implications for agricultural policy (IF13136) (2026-09-28). Accessed Oct 3, 2026.
  16. U.S. Government Publishing Office, Continuing Appropriations and Extensions Act, 2027 (P.L. 119-103), sec. 2019. Accessed Oct 3, 2026.
  17. 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.
  18. Cáñamo, La policía interviene el banco de semillas Dinafem (2020-11-01). Accessed Oct 3, 2026.