How To Grow The Ultimate Sour Diesel Autoflowers

We’re cultivating Sour Diesel autoflowering cannabis in coco coir using an IWS Trident flood & drain system at one of our fully legal grow sites in Spain. This combination of automated hydroponics, precision nutrient delivery, and carefully structured lighting forms the backbone of a setup that’s efficient, reliable, and capable of producing seriously heavy yields when dialled in properly.

This is not your average setup and can be a very expensive way to grow a small number of plants. However, it’s a method that works perfectly for our cannabis research projects. If you’re after something sturdy, automated, and consistent, this approach is a huge step forward – plus, with a little automation, you’ll rarely need to visit your grow space.

This guide outlines a detailed, week-by-week schedule using premium nutrients, smart environmental tuning, and a hands-off flood system that allows remote management with minimal physical interaction. It’s ideal for growers running 12 to 24 plants in 16L cloth pots, fed by a 750L IWS reservoir and lit by Phlizon FD8000 LED grow lights. Sour Diesel thrives in this system, showcasing vigorous growth, powerful stretching, and heavy resin production.

Note on Tank Size:
We use a 750L tank because it’s ideal for automated and remote-managed grows. If you’re hands-on or working smaller, a 400L tank is fine – just scale the ml/L feeding ratios accordingly.

Assuming you already have your propagator, lights (Phlizon FD8000), tent, fans, pest control, meters, humidifiers, dehumidifiers, and extraction system, you’ll also need:

• IWS Flood and Drain System
• Dutch Pro A+B Grow
•  Sho Gun Calimag or VitaLink CalMag
• High Nitrogen NPK 20-0-10
• Green Planet Massive Bloom or Dutch Pro Explode
• Advanced Nutrients Big Bud
• Mycorrhizal Fungi Powder
• Sour Diesel Autoflowering Cannabis Seeds
• Canna Coco Professional Pro

Why This Schedule Works

This method uses mycorrhizal fungi for early root development, balanced feeding per growth phase, and flood timings synced to plant and media response. EC, pH, and lighting are precisely tuned for coco, maximising nutrient uptake and growth.

Feeding, Lighting & Environmental Logic

• Nutrients: Sho Gun Calimag, Big Bud, High Nitrogen 20-0-10, Dutch Pro A+B, and Massive Bloom.
• Lighting: The Phlizon FD8000’s adjustable spectrum scales perfectly from seedling to flower.
• Flooding: 2–3 times daily depending on growth stage and moisture level.
• Root Support: Mycorrhizal fungi promote root mass – slow top growth early on is normal.

Important: If your plant’s visual progress doesn’t match the calendar (e.g. Week 2 looks like Week 3), stick to the same routine until it catches up. Mycorrhizal delays top growth while strengthening roots.

Weekly Breakdown

Week 1 – Transplant & Root Establishment

• Visual: Small seedlings, upright stems, bright green leaves.
• Stage: Germinated seedlings in 16L pots with coco and mycorrhizal inoculant.
• Lighting: 22 hours under LED propagator bars.
• Feed: Calimag 0.2ml/L, pH 5.8, EC 0.4–0.6.
• Watering: Misting every 30 minutes for 10 minutes.
• Milestone: Root development begins.

Week 2 – Root Expansion (Pre-Activation)

• Visual: Short, compact plants, deep green leaves, little height change.
• Light: 40% intensity, 80cm above canopy, 18–20 hours.
• Feed: Calimag 0.5–1ml/L, NPK 0.5ml/L, A+B 1ml/L, pH 5.8, EC 0.6–0.8.
• Milestone: Stronger root zone. Prepare flood system.

Week 3 – Vegetative Growth (Activate Flood)

• Visual: Fast new leaves and side branches, 20–30cm height.
• Light: 50% intensity, 60cm from canopy.
• Feed: Calimag 1ml/L, NPK 1ml/L, A+B 2ml/L, pH 5.8, EC 1.0.
• Flood: 3x per lights on, 5–8 minutes.
• Note: This stage may repeat until plants visually progress.

Week 4 – Stretch Phase

• Visual: Rapid height increase, internodes lengthen.
• Light: 60%, 50cm distance.
• Feed: Calimag 1ml/L, NPK 1.5ml/L, A+B 2ml/L, pH 5.8–5.9, EC 1.2–1.3.
• Flood: 2–3x daily.
• Milestone: Pre-flowers appear.

Week 5 – Flower Initiation

• Visual: White pistils forming, slight trichome sheen.
• Light: 70%, 45cm above canopy.
• Feed: Calimag 0.5ml/L, NPK 1ml/L, A+B 2ml/L, Big Bud 1ml/L, pH 5.8–6.0, EC 1.2–1.3.
• Flood: 3x per day.
• Milestone: Flowering onset, stretch slows.

Week 6 – Early Flowering

• Visual: Buds developing, diesel aroma emerging.
• Light: 80%, 45cm above canopy.
• Feed: Big Bud 2ml/L, Massive Bloom 5ml/L, A+B 2ml/L, Calimag 0.5ml/L, pH 5.9–6.0, EC 1.4–1.5.
• Flood: 3x per day.

Week 7 – Mid Flowering

• Visual: Buds swelling, pistils turning orange, trichome build-up.
• Light: 100%, 45cm from canopy.
• Feed: Massive Bloom 5ml/L, A+B 2ml/L, optional Calimag 0.5ml/L, pH 6.0, EC 1.3–1.4.
• Flood: 3x daily.
• Milestone: Peak flower development.

Week 8 – Late Flowering

• Visual: Dense buds, resin-coated, trichomes mostly cloudy.
• Feed: Massive Bloom 5ml/L, A+B 1ml/L, pH 6.0, EC 1.0–1.2.
• Flood: 3x daily.
• Milestone: Bud ripening. Prepare for flush.

Week 9 – Flush

• Visual: Fan leaves yellowing, buds mature, 10–20% amber trichomes.
• Feed: Plain pH’d water, EC 0.
• Flood: 2–3x daily.
• Milestone: Final resin push before harvest.

Week 10 – Final Flush & Harvest

• Visual: Fully faded leaves, sticky, ripe buds.
• Light: Optional 48h darkness before chop.
• Feed: None.
• Milestone: Trichomes 80–90% cloudy, 10–20% amber.

What to Watch For

• Stretch Management: Sour Diesel can stretch heavily – use LST rather than topping.
• EC Drift: Adjust feeding if runoff EC rises or drops unexpectedly.
• Trichome Reading: Use a loupe for ripeness – cloudy to amber transition is your harvest cue.
• Aroma Surge: Expect intense diesel terpenes during Weeks 6–8 – carbon filters recommended.

Final Word

This grow plan is built for serious growers chasing performance and consistency. Whether you’re learning IWS flood & drain or optimising an existing setup, this guide helps maximise every week – less guesswork, more yield, and total control over your Sour Diesel autoflower crop.