How to Grow Forbidden Runtz Auto
Forbidden Runtz Auto is a fast, potent, indica-dominant autoflower that crosses Forbidden Candy with Runtz Auto. It is a 70/30 indica with a high 26-28% THC, a fruity, citrus and sweet flavor over an earthy base, and a euphoric, relaxed effect. Quick to finish and easy to grow, it packs real Runtz flavor into a compact, beginner-friendly autoflower.
As an autoflower, Forbidden Runtz Auto flowers automatically with age rather than waiting on a change in the light cycle, so you do not need to switch your lights to start it blooming. It races from seed to harvest in about 9 weeks, one of the fastest ways to a potent, flavorful crop and a great fit for growers who want speed and simplicity.
Recommended Strains
Forbidden Runtz Auto
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THC | 26% - 28% (High) |
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Type | Autoflowering |
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Yield | High |
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Phenotype | 70% Indica / 30% Sativa |
Forbidden Runtz Auto HMC Edition
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THC | 26% - 28% (High) |
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Type | Autoflowering |
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Yield | High |
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Phenotype | 70% Indica / 30% Sativa |
Fast, potent and beginner-friendly, Forbidden Runtz Auto is a rewarding strain to grow. You can see the full genetics and buy Forbidden Runtz Auto seeds on the strain page, and browse the rest of our autoflowering seeds alongside it.
Strain Profile at a Glance
| THC | High (26-28%) |
|---|---|
| Lineage | Forbidden Candy x Runtz Auto |
| Type | Autoflowering |
| Genetics | 70% Indica / 30% Sativa |
| Climate | Temperate |
| Life cycle | 9 weeks (seed to harvest) |
| Harvest | All season |
| Height | 4.27 ft / 1.3 m |
| Yield indoor | 1.31-1.8 oz/ft² (400-550 g/m²) |
| Yield outdoor | 2.82-5.29 oz/plant (80-150 g/plant) |
| Grow difficulty | Easy, beginner-friendly |
| Flavors | Citrus, Earthy, Fruity, Sweet |
| Effects | Euphoric, Relaxed |
Promos & Deals
Growing an Autoflower Strain
Forbidden Runtz Auto is an autoflower, which means it starts to flower on its own schedule after a few weeks of growth, no matter what the light cycle is doing. You do not switch it to 12 hours of darkness to start flowering the way you would with a photoperiod plant. Instead, most growers keep it under long days, often 18 to 20 hours of light, for its whole life, which gives it maximum energy to build buds quickly.
Because it sets its own timetable, there is no long vegetative stage to manage, and the plant runs from seed to harvest in about 9 weeks, which is fast even for an autoflower. It stays compact at around 1.3 m, so it fits easily into a tent, on a balcony or in a small outdoor spot. That speed and small size are the real appeal here, letting you turn crops around quickly and even run several cycles in a season.
Climate and Where to Grow It
Forbidden Runtz Auto suits a temperate climate and grows well both indoors and outdoors where it gets strong light. Because it is an autoflower, it is not tied to the seasons the way a photoperiod plant is, so you can plant it almost all season and start a run whenever the weather is warm enough. Its compact 1.3 m frame makes it easy to tuck into a small space or to grow several plants at once.
Its high 26-28% THC places it firmly among our high-THC seeds, and its compact, indica-dominant structure sits naturally in our indica seeds. Its flavor and frost come straight from the Runtz side of its family, which you can explore through its parent, the Runtz Auto. For another take on those sweet Runtz genetics, Black Runtz is a close relative worth a look.
On yield it is productive for an autoflower, giving a strong 400-550 g/m² indoors in a filled canopy, while a single outdoor plant stays modest at around 80-150 g, which is normal for a compact auto. The practical takeaway is to grow a few plants together for a good haul. Keep temperatures around 68-80°F (20-27°C) and humidity sensible through flowering so the dense, frosty buds ripen clean.
Feeding Schedule (EC Guide)
Forbidden Runtz Auto is a fast, light-feeding autoflower, so go easy on nutrients rather than pushing it hard. Autos have a short life and can be sensitive to over-feeding, so start light, build gently, ease toward bloom nutrients as it starts flowering, then flush at the end so the fruity, citrus and sweet notes come through clean. The ranges below are a starting guide; adjust to your water and medium.
| Stage | EC (mS/cm) | Notes |
|---|---|---|
| Seedling | 0.4-0.6 | Very light feed while roots establish |
| Early growth | 0.8-1.2 | Build nitrogen gently as the plant grows |
| Early flower | 1.2-1.5 | Shift toward bloom nutrients (P and K) |
| Full flower | 1.4-1.7 | Peak bloom feed, kept moderate for an auto |
| Flush | 0.0-0.4 | Plain water for the final 1-2 weeks |
Flowering and Harvest
Forbidden Runtz Auto moves into flower on its own a few weeks from sprouting and runs to harvest in about 9 weeks from seed. It builds dense, chunky, frost-coated buds, developing a sweet, fruity aroma with a bright citrus lift over an earthy base as it ripens. That sweet, fruity-citrus scent and heavy frost are the signature of its Forbidden Candy and Runtz Auto parents.
Yields are strong for an auto, around 400-550 g/m² indoors in a full canopy, with a single outdoor plant closer to 80-150 g. Keep the colas supported and the canopy open so light reaches the lower buds, feed it gently through flower, and harvest when most of the trichomes have turned cloudy with a few amber for the fullest fruity-citrus flavor and the most rounded effect.
Drying and Curing
Dry whole plants or branches in a dark room at around 60°F (15-18°C) and 55-60% humidity for 7-14 days, until the thin stems snap rather than bend. A slow, even dry matters with such dense, frosty buds, because they can stay damp in the middle while the outside dries, and a gentle dry protects the sweet, fruity-citrus aroma that defines the strain.
Then cure the trimmed buds in sealed jars, burping them daily for the first week and letting them settle for three to four weeks. A proper cure is what brings out the full citrus, earthy, fruity and sweet character and smooths the smoke, turning a freshly dried harvest into the rich, sweet Runtz flavor Forbidden Runtz Auto is known for.
What to Do With Your Trim
Don’t bin the sugar leaves you remove while manicuring. Forbidden Runtz Auto is a frosty, resinous plant, so its trim is useful for dry sift, bubble hash or rosin. That resin and its sweet, fruity-citrus aroma make the trim worth keeping, turning offcuts into a flavorful concentrate run rather than waste, a nice bonus from a fast, high-THC autoflower.
Flavor and Terpenes
Forbidden Runtz Auto leads with a sweet, fruity flavor and a bright citrus lift over an earthy base, the rich Runtz-style profile it inherits from its parents. It is a smooth, full-bodied smoke, and a good cure brings that sweet, fruity-citrus character forward in the jar and on the inhale, with the earthy base giving it depth.
Its terpene profile frames that flavor. Caryophyllene adds a peppery, spicy edge, while humulene brings an earthy, hoppy note underneath. Beta-pinene lends a fresh, piney lift, and terpinolene a complex, herbal brightness. The sweet, fruity-citrus notes themselves come through from its Forbidden Candy and Runtz Auto genetics, with these terpenes giving the earthy, spicy, piney frame around them.
Effects and Best Use
With its high 26-28% THC and indica-dominant 70/30 make-up, Forbidden Runtz Auto delivers a potent, well-rounded experience. It is reported as euphoric and relaxed, pairing a bright, upbeat head with a comfortable, settled body. The potency is genuinely high for an autoflower, so a measured dose goes a long way, especially for newer smokers who may prefer to start slow.
That euphoric, relaxed profile makes it a natural choice for winding down in the afternoon or evening, well matched to its sweet, fruity-citrus flavor. The combination of real potency, a rich, sweet Runtz taste and a balanced, easy-going body is exactly why Forbidden Runtz Auto stands out among fast, flavorful autoflowers.
Common Problems and Pro Tips
Forbidden Runtz Auto is forgiving and beginner-friendly, but autoflowers have their own rules. Because the clock is always running, there is no way to extend the vegetative stage to fix a slow start, so get the seedling off to a healthy, unhurried beginning in its final pot and avoid transplant shock. Any check early on costs you final size, so steady, gentle care in the first weeks pays off most, especially on a quick 9-week plant.
Keep training gentle: light, low-stress training to open the canopy works well, but avoid heavy topping or anything that stresses an auto hard, since it has no time to recover. Its dense, frosty buds can also trap moisture, so keep the air moving and ease the humidity down as the flowers fill out to avoid trouble in the heart of the bud.
As a pro tip, feed it lightly rather than heavily, since autos are easy to over-feed and that can mute the sweet, fruity-citrus Runtz notes. Protect those terpenes with a proper plain-water flush and a full three to four week cure, save the frosty trim for concentrates, and harvest when most trichomes are cloudy with a few amber for a rich, flavorful result.
FAQ
Is Forbidden Runtz Auto an autoflower?
Yes. Forbidden Runtz Auto is an autoflowering strain, so it starts to flower automatically with age rather than waiting on a change in the light cycle. You do not switch it to a 12-hour dark period to bloom. Most growers simply keep it under long days for its whole life, which keeps the grow fast and very simple.
How much THC does Forbidden Runtz Auto have?
Forbidden Runtz Auto is a potent, high-THC strain, testing from about 26% up to 28% depending on the phenotype and how it is grown. Combined with its indica-dominant 70/30 genetics, the result is a euphoric, relaxed effect. It is strong for an autoflower, so it is well worth dosing carefully if you are newer to high-potency strains.
How long does Forbidden Runtz Auto take to grow?
Forbidden Runtz Auto runs from seed to harvest in about 9 weeks, which is fast even for an autoflower, since it flowers automatically without any change to the light cycle. Because it is an auto, it is not tied to the seasons, so you can start a run almost all season and even fit several quick cycles into a warm year.
What does Forbidden Runtz Auto taste like?
It has a sweet, fruity flavor with a bright citrus lift over an earthy base, the sweet, fruity Runtz profile it gets from its parents. Caryophyllene adds a peppery edge, humulene an earthy note, beta-pinene a fresh piney lift and terpinolene a herbal brightness. A proper three to four week cure brings that sweet, fruity-citrus character forward on the inhale.
How much does Forbidden Runtz Auto yield?
Forbidden Runtz Auto is productive for an autoflower, giving around 400-550 g/m² indoors in a full canopy, while a single outdoor plant stays modest at about 80-150 g. The practical move is to grow a few plants together. Give them good light, gentle feeding and support for the frosty colas to get the most from the crop.
Is Forbidden Runtz Auto indica or sativa?
Forbidden Runtz Auto is indica-dominant, at a 70/30 split, so it grows as a compact, sturdy plant with dense, frosty buds, staying short at around 1.3 m. That balance shows in its euphoric, relaxed effect, which pairs an upbeat head with a comfortable, easy-going body and suits afternoon or evening use.
