Critical Jack by Dr. Blaze
2 other breeders' versions of Critical Jack — compare flowering times side by side →
Growers reach for Critical Jack as an indica-leaning option, a cross of Jack Herer × Critical Plus Automatic out of Dr. Blaze. Indoors it typically finishes flowering in around 70 days after the flip to 12/12. The environment targets below are the same stage-by-stage bands the Cultivar journal grades real Critical Jack grows against.
🌿 Start a Critical Jack journal — free →
Similar strains
| Breeder | Dr. Blaze |
|---|---|
| Type | ruderalis/indica/sativa |
| Flowering time | ±70 days |
| Environment | Outdoors |
| Lineage | Jack Herer × Critical Plus Automatic |
| Descendants | Birrie Jack, MadCat's Backyard Stash - Killer Critical Jack, Critical Jack Autoflowering, Critical Jack Automatic |
🌱 Get Critical Jack seeds →
Affiliate link — supports Cultivar at no cost to you.
🧬 Explore the family: Jack Herer · Birrie Jack · MadCat's Backyard Stash - Killer Critical Jack · Critical Jack Autoflowering · Critical Jack Automatic
Ancestry Pedigree
Sensi Seeds
The Seed Bank
Original Strains
Cultivators Choice
Unknown or Legendary
Original Strains
Original Strains
Original Strains
Original Strains
Dinafem
Dinafem
Clone Only Strains
Mr Nice Seedbank
Original Strains
The Seed Bank
Dinafem
Joint Doctor
Super Sativa Seed Club
Original Strains
The Seed Bank
Unknown or Legendary
Original Strains
Original Strains
Unknown or Legendary
Original Strains
Growing Critical Jack: what to expect
As an indica-leaning plant, expect a modest stretch after the flip (roughly 50–100%) and dense bud structure — which makes late-flower humidity discipline the main risk: keep RH in the 40s once buds fatten to stay ahead of mold. Growers familiar with Jack Herer or Critical Plus Automatic will recognize much of its behavior. Whatever the listing says, the cut in YOUR tent is the ground truth: log feedings, readings, and photos, and let the trends — not the label — drive decisions.
Critical Jack FAQ
How long does Critical Jack take to flower?
Critical Jack typically flowers in around 70 days after switching to a 12/12 light schedule. Individual phenotypes vary, so judge harvest readiness by trichome color, not the calendar.
Is Critical Jack an indica or a sativa?
Critical Jack is listed as ruderalis/indica/sativa.
What are the parents of Critical Jack?
Critical Jack was bred from Jack Herer × Critical Plus Automatic by Dr. Blaze.
What environment does Critical Jack like?
Standard cannabis bands work well: VPD 0.8–1.1 kPa in veg and 1.0–1.4 kPa in flower, with humidity stepping down from 65–75% as a seedling to 40–50% in late flower. See the stage-by-stage table on this page.
📷 Growing Critical Jack and something looks off? Free AI photo diagnosis →
Facts compiled from public breeder listings. Growing Critical Jack? A structured journal — with your feedings, readings, and photos — is how you find what THIS cut actually wants.
Track your own grow free — the journal grades your environment against these bands →
Get the one-page grow reference card
VPD, pH by medium, deficiency symptoms and dry/cure targets on a single printable page. Free — plus the occasional grow-data breakdown. No spam, unsubscribe in one click.