C4 Auto
Cannabis seeds
by Fast Buds
C4 Auto Cannabis Seeds by FastBuds
C4 Auto is an autoflowering feminised cannabis seed from FastBuds that packs the genetics of three legendary strains — White Widow, Skunk, and Big Bud — into a compact, fast-finishing plant. With indoor yields reaching 450–600g/m² and a seed-to-harvest cycle of just 8 weeks, this is one of the most productive autos we've come across for its size. The 3-seed pack gives you enough to fill a small tent without committing to a full breeding project.
Why C4 Auto Seeds Deserve Your Tent Space
Three parent strains, zero filler genetics. FastBuds crossed White Widow (the resin factory), Skunk (the backbone of modern cannabis breeding), and Big Bud (the yield monster) with a ruderalis line to create C4 Auto. The result is a strain that doesn't ask you to choose between potency and productivity — you get both.
We'd pick C4 Auto over most budget autos in the FastBuds lineup for one reason: the yield-to-time ratio is hard to beat. At 450–600g/m² indoors in just 8 weeks from germination, you're looking at commercial-level output from a plant that tops out at 90–120cm. That height makes her manageable in a standard 80x80 or 100x100 tent without the vertical stretch that sends some sativas crashing into your light fixture. Outdoors, expect 50–350g per plant depending on your climate and how much sun she gets — the short lifecycle makes C4 Auto viable even in northern European summers where the window between last frost and first rain feels absurdly short.
The honest limitation? At 16% THC, C4 Auto isn't going to compete with the 25%+ photoperiod monsters. If you're chasing the absolute highest potency, something like FastBuds' Gorilla Cookies Auto will hit harder. But 16% THC paired with 1.1% CBD creates a more balanced cannabinoid profile — the kind that delivers a clear cerebral effect with noticeable physical relaxation without nailing you to the sofa for four hours. Traditionally, strains with this THC-to-CBD ratio have been favoured for evening use when you want to unwind without completely switching off.
C4 Auto Seed Specifications
| Specification | Detail |
|---|---|
| Seed Bank | FastBuds |
| Seed Type | Autoflowering, Feminised |
| Genetics | White Widow x Skunk x Big Bud x Ruderalis |
| THC Content | 16% |
| CBD Content | 1.1% |
| Lifecycle | 8 weeks from germination to harvest |
| Indoor Yield | 450–600g/m² |
| Outdoor Yield | 50–350g per plant |
| Height | 90–120cm |
| Seeds per Pack | 3 |
| SKU | CSFB0003 |
C4 Auto Genetics — What the Parents Bring to the Table
Understanding the lineage tells you exactly what to expect in the grow room. White Widow contributes the resin production — those crystal-crusted buds C4 Auto is known for come directly from this Dutch coffeeshop classic. The trichome coverage is dense enough that you can feel the stickiness through nitrile gloves when handling mature colas.
Skunk brings structural stability and that unmistakable pungent aroma. If you've ever walked past a Skunk plant in flower, you know the smell — sharp, skunky, fills a room in seconds. C4 Auto inherits this, so a carbon filter isn't optional unless you want your neighbours asking questions. Big Bud is where the yield numbers come from. The calyx-to-leaf ratio leans heavily toward bud production, which means less trimming time per gram harvested. For anyone who's spent an evening hand-trimming a leafy plant, that alone is worth the price of admission.
The ruderalis genetics handle the autoflowering trait. No light schedule changes needed — C4 Auto will transition from vegetative growth to flowering on her own internal clock regardless of your photoperiod. Run her under 18/6 or 20/4 from start to finish and she'll do the rest.
How to Grow C4 Auto Seeds
- Germinate your C4 Auto seeds using the paper towel method or directly in a small pot of moist, lightly fertilised soil. Taproots typically emerge within 24–72 hours.
- Transplant seedlings (if started in paper towel) into their final container as soon as the taproot is 1–2cm long. Autos don't love being repotted — going straight into the final pot avoids transplant shock that can stunt growth during the short vegetative window.
- Use 11–15 litre pots for the best balance between root space and manageable watering. Larger pots can boost yield but increase the risk of overwatering for less experienced growers.
- Set your light schedule to 18 hours on, 6 hours off from day one. Some growers push to 20/4 for extra photosynthesis — C4 Auto handles both well.
- Keep feeding moderate during the first 2–3 weeks. Autoflowers have a shorter veg phase, so heavy nitrogen early on can cause nutrient burn before the plant has the root mass to handle it.
- Expect the transition to flower around week 3–4. You'll see white pistils forming at the nodes — this is your cue to shift toward bloom nutrients with higher phosphorus and potassium.
- Maintain relative humidity around 40–50% during flowering to prevent mould in those dense, Big Bud-inherited colas.
- Harvest at week 8 from germination. Check trichomes with a jeweller's loupe — mostly milky with a few amber heads gives you the balanced effect C4 Auto is bred for.
Complete your setup with a grow tent and carbon filter — C4 Auto's Skunk heritage means she'll announce herself to the entire building without proper ventilation. Pair with an 80x80 or 100x100 grow tent for the right fit, and grab some bloom nutrients to maximise those Big Bud yields during the flowering phase.
C4 Auto Yield and Potency Compared
| Trait | C4 Auto (FastBuds) | Typical Budget Auto |
|---|---|---|
| Indoor Yield | 450–600g/m² | 300–400g/m² |
| Outdoor Yield | 50–350g/plant | 30–150g/plant |
| THC | 16% | 12–15% |
| CBD | 1.1% | Trace–0.5% |
| Seed to Harvest | 8 weeks | 9–11 weeks |
| Max Height | 90–120cm | 80–130cm |
Frequently Asked Questions
How long does C4 Auto take from seed to harvest?
Eight weeks from germination. That's one of the shortest lifecycles in the FastBuds catalogue, making C4 Auto a solid choice for growers in regions with short summers or anyone who wants fast turnaround indoors.
What yield can I realistically expect from C4 Auto indoors?
FastBuds lists 450–600g/m² under optimised conditions. Most home growers report 400–500g/m² with decent lighting and nutrients. The Big Bud genetics in the lineage are what push the yield numbers above average for an autoflower.
Is C4 Auto suitable for beginner growers?
Yes. The autoflowering trait means no light schedule changes, and the 8-week lifecycle limits the damage if you make a mistake. Start with moderate feeding and don't overwater — she's forgiving but not indestructible.
Does C4 Auto smell strongly during flowering?
Very much so. The Skunk parentage gives C4 Auto a sharp, pungent aroma that intensifies during weeks 5–8. A carbon filter and proper extraction are not optional for indoor grows unless you want the whole building to know.
What's the difference between C4 Auto and other FastBuds autoflowers?
C4 Auto prioritises yield and speed over extreme potency. At 16% THC with 1.1% CBD, she's more balanced than strains like Gorilla Cookies Auto (which pushes past 25% THC). The trade-off is a more approachable effect and significantly faster harvest.
Can I grow C4 Auto outdoors in northern Europe?
The 8-week lifecycle makes C4 Auto one of the better options for short northern summers. Expect 50–350g per plant outdoors depending on sunlight and conditions. She'll finish before autumn rains become a mould risk.
How tall does C4 Auto get?
Between 90 and 120cm at full maturity. That's manageable in most grow tents without needing to train or top aggressively — though some LST (low stress training) can help expose lower bud sites to more light.
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.