Jack Herer Auto
Cannabis seeds
by Greenhouse Seeds
Jack Herer Auto Cannabis Seeds by Greenhouse Seeds
Jack Herer Auto is an autoflowering feminised cannabis seed that delivers the iconic sativa-dominant genetics of the original Jack Herer in a fast, compact, and beginner-friendly format. Bred by Greenhouse Seeds — the outfit that took the original JH to victory at the 1994 High Times Cannabis Cup — this autoflower version preserves the balanced mind-body effect while cutting the total grow cycle down to just 9 weeks. Available in packs of 3, 5, or 10 seeds.
Which Pack Size of Jack Herer Auto Seeds?
Jack Herer Auto comes in three pack sizes: 3, 5, or 10 seeds. All seeds are feminised and autoflowering — every seed produces a flowering female without the need to change your light schedule.
| Pack | Seeds | Best For |
|---|---|---|
| 3 seeds | 3 | First-time growers testing the strain, or a single outdoor run |
| 5 seeds | 5 | A full indoor tent cycle with a spare seed or two |
| 10 seeds | 10 | Multiple harvests, sea-of-green setups, or stocking up for the season |
If you're running a 60x60cm or 80x80cm tent, 3–4 plants of this size (80–100cm) fill the canopy nicely. The 5-pack gives you room for one dud or one pheno you want to keep separate. The 10-pack is the move if you're planning successive harvests — stagger your planting by two weeks and you'll have a near-continuous supply.
Why Jack Herer Auto Deserves a Spot in Your Grow
The original Jack Herer has been a coffeeshop staple in Amsterdam for decades. Named after the American cannabis activist who wrote The Emperor Wears No Clothes, the strain won the 1994 High Times Cannabis Cup and never really left the conversation. Greenhouse Seeds took those genetics — a sativa-dominant hybrid — and crossed them with ruderalis to create an autoflowering version that doesn't ask you to fiddle with light cycles or wait four months for harvest.
Here's what makes this one stand out from the pile of autoflowers we carry: the yield. For a long time, autos had a reputation for producing wispy, underwhelming buds. Jack Herer Auto pushes back hard against that — we're talking up to 700g/m² indoors and 80–100g per plant outdoors. That's serious weight for a plant that tops out at 80–100cm and finishes in 9 weeks from seed. The flowering period itself is about 7 weeks, with 2 weeks of vegetative growth before the plant flips itself. No timer changes, no light deprivation setups. It just goes.
The honest limitation? Autoflowers give you less control over plant size. You can't extend the veg phase to fill a bigger canopy because the plant decides when to flower, not you. If you want a monster tree for your garden, a photoperiod Jack Herer will serve you better. But if you want speed, stealth, and a genuinely impressive harvest from a compact plant, this auto version is the smarter pick for most home growers.
Jack Herer Auto Specifications
| Specification | Detail |
|---|---|
| Seed Bank | Greenhouse Seeds |
| Seed Type | Autoflowering, Feminised |
| Genetic Dominance | Sativa-dominant (with ruderalis) |
| Parent Genetics | Jack Herer x Ruderalis |
| Total Grow Cycle | Approximately 9 weeks (seed to harvest) |
| Flowering Time | 7 weeks |
| Height | 80–100cm |
| Indoor Yield | Up to 700g/m² |
| Outdoor Yield | 80–100g per plant |
| Minimum Temperature | 10°C (do not grow below this) |
| Light Cycle Dependence | None — flowers automatically regardless of light schedule |
| Available Pack Sizes | 3, 5, or 10 seeds |
Running Jack Herer Auto indoors? Pair these seeds with a complete grow tent kit — tent, light, ventilation, and carbon filter in one box. For outdoor growers, a bag of quality soil mix and some root stimulator will give these autos the head start they need during their short vegetative window.
Growing Jack Herer Auto Seeds — What to Expect
We've seen a lot of growers overthink autoflowers. The whole point of Jack Herer Auto is simplicity: plant the seed, keep conditions stable, and let the genetics do the work. That said, there are a few things worth knowing before you pop your first seed.
Because the vegetative phase is only about 2 weeks, you don't get a second chance at early training. If you want to top or LST (low-stress training) this plant, do it early — around day 10–14 — and be gentle. Heavy defoliation or late topping on an auto can stunt growth, and with a fixed timeline, the plant can't recover the way a photoperiod strain would. Light stress training (bending and tying) works well with this cultivar and helps expose lower bud sites to light without shocking the plant.
Temperature matters more than you'd think. Jack Herer Auto can handle a range of climates, but Greenhouse Seeds specifies a minimum of 10°C. Below that, growth slows dramatically and you risk root issues. Indoors, keep your tent between 20–26°C during lights-on and don't let it dip below 16°C during lights-off. Outdoors in northern Europe, that means planting between May and August for the best results — though the autoflowering trait technically lets you plant any time of year as long as temperatures cooperate.
One thing we'd flag: don't transplant autoflowers if you can avoid it. Start them in their final pot — 7–11 litres is the sweet spot for this strain. Transplant shock eats into that short veg phase and costs you yield. Fabric pots work brilliantly here because they air-prune roots and prevent circling.
How to Grow Jack Herer Auto Seeds
- Germinate your Jack Herer Auto seeds using the paper towel method or by placing them directly into moist soil at a depth of about 1cm. Keep the temperature around 22–25°C until the taproot emerges (usually 24–72 hours).
- Plant the germinated seed directly into its final container — a 7–11 litre pot filled with light, airy soil. Autoflowers don't like heavy, waterlogged substrates. Avoid transplanting.
- Provide 18–20 hours of light per day from seed to harvest. Autoflowers don't need a 12/12 flip, and more light hours means more energy for bud production. LED or HPS both work; aim for at least 300W equivalent for a 1m² canopy.
- During the first 2 weeks (vegetative phase), keep feeding light — quarter-strength nutrients at most. Autoflowers are sensitive to overfeeding, especially in the early stages.
- If you plan to train the plant, begin low-stress training around day 10–14 by gently bending the main stem and tying it down. This opens the canopy and encourages multiple bud sites.
- Around week 3, the plant will begin to show pre-flowers and transition into bloom automatically. Switch to bloom nutrients gradually. No light cycle change is needed.
- Through weeks 3–9, maintain stable conditions: 20–26°C, 40–50% relative humidity during flowering, and consistent watering. Watch for signs of nutrient burn (brown leaf tips) and back off feeding if needed.
- In the final 7–10 days before harvest, flush with plain water to clear residual nutrients from the soil. Trichomes should appear milky-white with some turning amber — that's your harvest window.
- Cut, trim, and hang branches to dry in a dark room at 18–20°C and 55–60% humidity for 7–10 days. Cure in airtight jars for at least 2 weeks, burping daily for the first week.
Sensory Profile and What Sets Jack Herer Auto Apart
The original Jack Herer is famous for a reason — it has a terpene profile that hits you before you even open the jar. Expect a sharp, spicy pine on the nose with a peppery undertone and a faint sweetness that rounds it out. The buds themselves are dense for a sativa-dominant plant, coated in a visible layer of trichomes that makes them sticky to the touch. Compared to something like Amnesia Haze Auto, Jack Herer Auto leans more towards that classic spicy-herbal character rather than a citrus-forward profile.
The effect from the original JH is a balanced sativa-dominant experience — cerebral and uplifting with enough body relaxation to keep things grounded. The auto version preserves this character. It's the kind of strain that works during the day without leaving you glued to the sofa, which is exactly why the original became a coffeeshop legend in the first place.
Frequently Asked Questions
How long does Jack Herer Auto take from seed to harvest?
About 9 weeks total. That breaks down to roughly 2 weeks of vegetative growth followed by 7 weeks of flowering. The plant transitions to bloom automatically — no light cycle change required.
Do I need to change the light schedule for Jack Herer Auto?
No. Autoflowering seeds flower based on age, not light exposure. Most growers run 18–20 hours of light per day from seed to harvest for maximum yield. A 12/12 schedule works but reduces output.
Can I grow Jack Herer Auto outdoors in the UK or northern Europe?
Yes, as long as temperatures stay above 10°C. The best window is May through August. The 9-week cycle means you can fit a full harvest into a single summer, and some growers manage two successive runs.
What yield can I expect from Jack Herer Auto?
Indoors under good conditions, up to 700g/m². Outdoors, expect 80–100g per plant. Actual yield depends on light intensity, pot size, nutrients, and whether you train the plant during early veg.
Should I top or train Jack Herer Auto?
Low-stress training (LST) works well — bend and tie the main stem around day 10–14 to open the canopy. We'd avoid topping autos unless you're experienced, as the short veg phase leaves little recovery time if the plant gets stressed.
How tall does Jack Herer Auto grow?
Between 80 and 100cm. That's compact enough for a small tent or a balcony grow, but tall enough to produce a solid canopy of bud sites — especially if you train early.
Is Jack Herer Auto suitable for first-time growers?
Very much so. The autoflowering trait removes the need to manage light cycles, and the natural resilience of the ruderalis genetics makes it forgiving of minor mistakes. Start in the final pot, don't overfeed, and you'll be fine.
Last updated: April 2026
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Medical disclaimer. This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before use of any substance.