Jack Flash cannabis seeds packaging — Royal King Seeds the UK
Hybrid
THC 19%
🎨 Creative
HybridFeminizedIn Stock

Jack Flash Feminized

Feminized PhotoperiodSee Lab Report →

Jack Flash Feminized — hybrid cannabis seeds suited to UK growing conditions. 19% THC with creative, energetic, relaxed effects. Fast, discreet UK delivery.

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£11.79
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About Jack Flash Feminized

Can I grow Jack Flash outdoors in the UK? Absolutely. This 60/40 hybrid is well-suited to the UK outdoor season running April through October. The balanced genetics handle UK conditions reliably, adapting to everything from damp coastal air to the drier east of the country. Flowering takes 55 to 75 days, placing your harvest window squarely in September or October for most UK latitudes.

What kind of yield should I realistically expect? We do not publish a per-strain yield figure for this cultivar, so treat any number you see elsewhere with caution. Yield depends far more on your lighting, pot size, feeding and training than on genetics alone. At 19% THC and a myrcene-forward terpene profile, the quality-to-effort ratio makes Jack Flash genuinely worthwhile.

Is this strain forgiving for newer growers? Reasonably so. A grower with basic knowledge of pH, feeding schedules, and light cycles will manage fine. It is not the most forgiving plant if you neglect it entirely, but it will not collapse at the first missed watering either.

More Questions UK Growers Ask About Jack Flash

What growing medium works best for this strain? For maximum flavour complexity, organic soil blended with 30% perlite and enriched with slow-release amendments (blood, fish and bone, rock phosphate, kelp meal — all readily available at a garden centre or your local hydroponics shop). For maximum yield, coco coir with automated fertigation at EC 1.4-1.8 during bloom. Both approaches produce excellent results with this hybrid genetics.

How does it handle British summer heat? Handles heat reasonably well thanks to the hybrid vigour. Keep root zone temperatures below 28°C with mulch or light-coloured pots, and avoid transplanting during heatwave conditions.

When should I start feeding bloom nutrients? Within the first week of visible pistil formation. This cultivar's 60/40 genetics shifts its nutritional demand rapidly at the transition. Phosphorus and potassium uptake increases noticeably, whilst nitrogen demand drops. An organic top-dress of bat guano and sulphate of potash works well for soil growers; hydro and coco growers should switch to a bloom-ratio formula (low N, high PK) immediately.

Indoor or outdoor — which is better for this strain? Both work. Indoor gives you control over the 55 to 75 days environment. Outdoor in the UK growing season (April-October) lets the plant reach its full around 600 g/plant potential with natural sunlight intensity that even expensive LEDs struggle to match. Flowering: 55 to 75 days. Outdoor yield: around 600 g/plant. Plant height: up to 180 cm (indica pheno ~100 cm). Rated intermediate difficulty.

What to Expect When Using Jack Flash

UK customers report creative, energetic, relaxed as the defining characteristics, and our experience aligns with that consensus. At 19% THC, this hybrid sits in a potency bracket where versatility is the main advantage. Morning users report functional clarity at lower doses. Evening users report satisfying relaxation at higher doses. The ${indica}/${sativa} balance means the dominant effect direction shifts with consumption amount rather than being locked into a single character. The Myrcene/Limonene terpene combination imparts a flavour that lingers on the palate — earthy and slightly sweet with a fruit-like finish.

Ideal settings: adaptable across occasions — adjust dose to match the energy level your situation calls for.

Terpene Breakdown

Primary: Myrcene · Secondary: Limonene · Tertiary: Pinene. This particular terpene trio appears frequently in award-winning cultivars and produces a nose that most UK growers find immediately appealing when jars are first opened after curing. The myrcene dominance anchors the aroma, limonene provides mid-range character, and pinene contributes a subtle background note that distinguishes this strain from others sharing the same primary terpene.

Suitability and Recommendations

Jack Flash suits growers with fundamental skills already established. You should understand pH management, basic nutrient ratios, and light cycle requirements before committing to this cultivar — it will not hold your hand, but it will not punish minor mistakes harshly either. Photoperiod genetics give you complete control over plant size and harvest timing — extend the vegetative phase for larger plants or flip early for a quicker turnaround in compact spaces. The UK growing season (April through October) accommodates the 55 to 75 days bloom period comfortably for outdoor cultivators across the country. Shipped discreetly across the UK with our germination guarantee.

Effects

🤩Creative
77% of people reported feeling Creative
🤑Energetic
64% of people reported feeling Energetic
😌Relaxed
58% of people reported feeling Relaxed
😊Happy
51% of people reported feeling Happy
🤗Euphoric
47% of people reported feeling Euphoric
😎Uplifted
38% of people reported feeling Uplifted
🤤Hungry
34% of people reported feeling Hungry
😴Sleepy
31% of people reported feeling Sleepy
😆Giggly
24% of people reported feeling Giggly

Strain Type

Indica 60%Sativa 40%

Strain Data Sheet

🧬THC19% - 23% (Medium-High)
🌿LineageJack Herer × Super Skunk × Haze
🔬TypeFeminized Hybrid
🌡ClimateTemperate, adaptable
📅HarvestLate Sept – Oct, UK outdoor (typical)
📏Heightup to 180 cm (indica pheno ~100 cm)
⚖️YieldMedium – High
🏠Yield Indoor400 – 500 g/m² (typical)
🌳Yield Outdooraround 600 g/plant
Flowering Time55 to 75 days

Packaging

Resealable +
RK
Royal King Seeds
Photoperiod
Feminized Premium
Seeds
Premium Genetics
Protective vial
Resealable +
Royal King Seeds supplies seeds as adult novelty collectibles and for genetic preservation. Purchasers must comply with all applicable UK Commonwealth, state, and territory legislation.
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Jack Flash Feminized
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💧Waterproof coating
🛡️Aluminium interior lining
🏷️Protective sticker
📱QR code verification
🔢Scratchable serial number

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Jack Flash Feminized — Breeder Information

Royal King Genetics

Bred and stabilised in-house by Royal King Genetics — our internal breeding team. Every batch is QC'd and germ-tested above 99% before it ships. Read the full breeding process and about page.

Stabilisation Level
F5 IBL
Generations
5+
Breeding Programme
IBL Heritage Programme — five-generation inbred fixing
Stabilisation Notes — What This Means for Your Grow

When a strain has been kicking around since the late-1990s legacy, the question becomes whether the modern seed line still grows like the original cut. Our F5 IBL on Jack Flash answers that — five rounds of selection have re-locked the structural balance that made the cultivar a benchmark.

Breeding Goal

Restabilise a late-1990s legacy cultivar to contemporary uniformity standards.

Selection Focus

Chosen for balanced indica/sativa expression, terpene fidelity and pack-to-pack uniformity.

Pollen / Mother Source

Royal King Genetics select-mother programme — pollen drawn from an internally maintained reversed-female line.

Last Batch QC Verified
18 May 2026· 99%+ germination