Critical Jack Feminized Seeds by Silent Seeds – High-Yielding Sativa-Dominant Hybrid for Indoor & Outdoor Growing

Critical Jack feminized seeds by Silent Seeds deliver top-tier yields and premium-quality buds with a vibrant sativa-driven experience — all in a stable, easy-to-grow package that excels both indoors and outdoors.

Overwhelmed by complicated grow plans and underwhelming harvests? You’ve done your research, but still feel stuck on where to start — especially when your seeds promise big results but give zero guidance. You follow generic advice, only to end up with stretched plants, weak flavor, or worse: bud rot sneaking in because you didn’t know when to adjust humidity.

That uncertainty kills confidence. You start questioning the seed, the nutrients, even your own skills. But the truth? It’s not you — it’s the lack of a clear, step-by-step process tailored to your strain’s unique needs. Without it, even the best genetics can fall flat.

With Critical Jack, you get more than just seeds — you get a proven roadmap to success. This strain thrives when grown with intention, and our phase-based guide ensures you hit every milestone: from germination to harvest, you’ll know exactly what to do, when to do it, and why it matters. No guesswork. No wasted cycles. Just consistent, resin-dripping results.

Preparation: Set Up for Success

Before germination, ensure your environment is stable and ready. This strain rewards preparation with explosive growth and resilience.

• Check pH of water and soil: aim for 6.0–6.5 in soil or 5.8–6.2 in coco
• Prepare pots: 11–18 L final size for indoor; up to 25 L outdoors
• Set lighting: 18/6 photoperiod for veg, 12/12 to trigger flowering
• Confirm temperature: 22–26 °C during veg, 20–25 °C in flowering
• Use a well-aerated soil mix like All Mix Peat Free 50 lt. Bio Bizz for strong root development

Germination and Early Growth

Start strong with gentle handling and optimal conditions to ensure vigorous, healthy seedlings.

1. Germinate seeds in a moist paper towel or starter cube at 22–25 °C
2. Transplant once the taproot reaches 1–2 cm (0.4–0.8 in)
3. Place in small pots (0.5–1 L) under low-intensity light
4. Water lightly — avoid saturation to prevent damping off
5. Apply a root stimulant like Naturbac Trabe to boost early root mass

Vegetative Growth: Build a Strong Foundation

This is where Critical Jack shows its power — fast, tall, and resilient. Manage its stretch and structure early.

1. Switch to 18/6 light cycle and increase intensity gradually
2. Repot to final container early — this strain hates being rootbound
3. Use low-stress training (LST) to control height and improve light penetration
4. Avoid topping or FIM — this sativa-dominant hybrid recovers slowly
5. Feed with balanced nutrients; avoid excess nitrogen to prevent weak stems

Flowering: Maximize Yield and Resin

From week one, this strain begins its transformation into a trichome-covered powerhouse.

1. Switch to 12/12 light cycle to initiate flowering
2. Expect a pronounced stretch — up to 2–3 m (6.56–9.84 ft) outdoors
3. Reduce humidity to 40–50% to prevent mold in dense buds
4. Boost flowering with TopBooster Aptus for heavier colas and terpene production
5. Monitor trichomes: harvest when mostly milky for a cerebral high

Harvest, Drying & Curing

End strong — proper post-harvest handling locks in flavor, potency, and smoothness.

Flush plants 7–10 days before harvest to remove nutrient buildup. Trim carefully, preserving trichomes. Dry slowly at 18–22 °C and 50–60% RH for 10–14 days. Cure in glass jars, burping daily for 2–4 weeks to enhance aroma and smoothness.

Why This Flow Beats Guesswork

• Consistent, high yields up to 625 g/m² (1.46 oz/ft²)
• Fewer mistakes from overwatering or poor training
• Better control over plant structure and light exposure
• Reduced risk of mold and pests through proactive climate control
• Enhanced flavor and resin production with targeted feeding
• Confidence in every step — no more second-guessing

Technical specifications

• Breeder / Brand: Silent Seeds
• Type: Feminized
• Dominance: 60% Sativa / 40% Indica
• Genetics / Cross: Critical+ × Jack Herer
• Flowering time: 60 days (indoor), harvest outdoors late September to early October
• Indoor yield: 625 g/m² (1.46 oz/ft²)
• Outdoor yield: 1200 g/plant (2.65 lb/plant)
• Indoor height: 80–120 cm (2.62–3.94 ft)
• Outdoor height: up to 3 m (9.84 ft)
• Difficulty: Medium
• Structure: Open, vigorous, long internodes
• Climate: Temperate, Mediterranean, continental
• Resistance: High resistance to mold, pests, and stress
• Training: Suitable for LST and SCROG; avoid aggressive pruning
• Recommended pot: 11–25 L depending on space
• Light: 18/6 veg, 12/12 flowering
• Temperature: 22–26 °C veg, 20–25 °C flowering
• Humidity: 60–70% seedling, 50–60% veg, 40–50% flowering
• pH: 6.0–6.5 (soil), 5.8–6.2 (coco/hydro)
• THC: 15–20%
• CBD: 0.01–0.2%
• Aromatic profile: Haze, cedar, pine, incense, citrus
• Flavour: Woody, spicy, sweet, lemony
• Effect: Cerebral, energizing, creative, uplifting

Frequently Asked Questions

How long does Critical Jack take to flower?

Indoors, flowering lasts about 60 days. Outdoors, harvest is ready from late September to early October, depending on climate.

Is Critical Jack mold resistant?

Yes, it shows strong resistance to mold and powdery mildew, especially when humidity is kept below 50% in flowering.

Can I grow Critical Jack outdoors in a colder climate?

Absolutely — its robust genetics handle cooler temperatures well, as long as it gets enough sunlight and protection from heavy rain.

What’s the best way to increase yield?

Use SCROG or LST during veg, ensure proper pot size, and feed with bloom boosters like K-Boost Aptus during peak flowering.

Personal Experience of Pevgrow’s CEO (Alan)

I’ve grown Critical Jack for years, and it’s one of those rare strains that delivers every time — whether you're a novice or a pro. I started with a 15 L pot indoors under LED, using LST to keep it manageable. It stretched hard in pre-flower, so I tied down the main colas early. I fed it lightly at first, then ramped up with TopBooster Aptus in mid-flower. The trichome coverage was insane — sticky as hell. I harvested at 70% milky trichomes for a clear, energetic high. Outdoors, I’ve seen it hit over 1.2 kg (2.65 lb) per plant in Spain. My only tip? Don’t over-prune. Let it shine.