Runtz XL Auto® by Sweet Seeds – 8-Week Autoflowering Powerhouse with Sweet Fruity Aroma

Runtz XL Auto® by Sweet Seeds is a high-performance, 8-week autoflowering strain delivering massive yields, intense flavor, and a balanced high—no timing the lights or stress over schedules.

Still stuck with slow, low-yielding autos?

Let’s be real: most autoflowers promise big but deliver small nugs, weak flavor, or inconsistent results. You end up waiting weeks for a harvest that barely fills a jar, with smoke that lacks punch or personality.

Wasting time on underperforming genetics?

Weak plants stretch too much, crash in humidity, or fold under heat. You nurse them through every phase, only to find airy buds and bland taste after all that effort. And if you're growing for flavor or effect, settling for mediocrity just kills the vibe.

Meet Runtz XL Auto® – the 8-week wonder that grows like a beast

Bred from elite Runtz and Sweet Gelato Auto®, this 6th generation autoflower packs serious terpenes, serious size, and serious yield. With up to 550 g/m² indoors and a rich, sweet-fruity bouquet, it finishes in exactly 8 weeks—no guesswork, no stress. It’s resilient, easy to grow, and delivers dense, sticky buds that smell like a candy store and hit with creativity and calm.

Technical specifications

• Breeder / Brand: Sweet Seeds
• Type: Autoflowering
• Genetics: Runtz × Sweet Gelato Auto® (SWS88)
• Indica / Sativa / Ruderalis: 47.1% / 52.5% / 0.4%
• THC: 17–25%
• CBD: 0.5%
• Indoor yield: 400–550 g/m² (12–16 oz/ft²)
• Outdoor yield: 50–175 g/plant (1.76–6.17 oz/plant)
• Harvest time: 8 weeks from germination
• Indoor height: 0.60–1.20 m (1.97–3.94 ft)
• Outdoor height: 0.60–1.20 m (1.97–3.94 ft)
• Difficulty: Low
• Structure: Strong branching, vigorous stretch
• Resistance: High resistance to heat, stress, and mold
• Training: Suitable for LST; avoid topping or FIM
• Recommended pot: 18–27 L final pot
• Light cycle: 18–20 hours daily
• Flavor: Sweet, fruity, candy-like
• Aromatic profile: Limonene, myrcene, caryophyllene
• Effect: Balanced – relaxing, stimulating, creativity-boosting

Why Runtz XL Auto® outperforms basic autoflowers

This isn’t your average auto. Sweet Seeds spent six generations refining this line to reduce ruderalis traits and maximize potency, flavor, and yield. The result? A plant that grows fast, finishes fast, and smokes like a premium photoperiod.

• Finishes in just 8 weeks – perfect for quick turnover or multiple harvests
• Massive yields even in organic soil – no need for complex feeding
• Explosive growth and dense bud structure – fills space fast
• High terpene content – delivers a room-filling, sweet-fruity aroma
• Resilient to stress and temperature swings – great for beginners and outdoor grows
• Sticky, compact buds – minimal trimming, maximum impact

Real benefits you’ll experience

You’re not just growing a plant—you’re unlocking a next-level experience. With Runtz XL Auto®, you get:

• A harvest every two months – ideal for consistent supply
• Buds that smell like dessert and taste even better – no harshness, just smooth, hazy sweetness
• A balanced high that calms the body and sparks the mind – perfect for daytime or evening
• Minimal maintenance – it grows strong even with minor mistakes
• Discreet growing potential – small footprint, big returns
• Confidence in every seed – high germination and uniformity

Step-by-step growing guide

1. Germinate seeds in a moist paper towel or starter cube at 22–25 °C and high humidity.
2. Transplant once the taproot is 1–2 cm long into a final pot of 18–27 L with well-aerated soil.
3. Provide 18–20 hours of light daily – no need to change the photoperiod.
4. Water lightly at first, increasing as the plant grows; maintain pH 6.0–6.5 (soil) or 5.8–6.2 (coco).
5. Use low-stress training (LST) early to control height and boost light exposure.
6. Monitor trichomes from week 6; harvest when mostly milky with some amber for a balanced effect.
7. Dry buds slowly at 18–20 °C and 50–60% RH, then cure in jars for 2–4 weeks for maximum flavor.

Frequently Asked Questions

How long does Runtz XL Auto® take to harvest?

From germination to harvest, it takes exactly 8 weeks. No need to monitor flowering phases—just plant and wait.

Is this strain good for beginners?

Absolutely. It’s resilient, forgiving, and grows fast with minimal input. Just keep the basics right and you’ll be rewarded.

Can I grow Runtz XL Auto® outdoors?

Yes! It thrives outdoors in warm, sunny climates. Just protect it from heavy rain and extreme cold.

Does it need special nutrients?

No. It performs great with standard cannabis nutrients. For better results, use a balanced flowering booster like Bloom Booster.

What does it smell like during grow?

Strong and sweet—especially in flowering. Use a carbon filter if discretion is needed.

Personal Experience of Pevgrow’s CEO (Alan)

I’ve tested dozens of autos, but Runtz XL Auto® stood out from day one. I grew three plants in 20L pots under a 450W LED, 18/6, in my grow tent. They exploded in veg—doubled in size in just 10 days. I did light LST to spread the canopy, and by week 4, they were already showing heavy bud sites. No stretch drama, no nutrient burn, no pests. At week 8, I harvested 510 g/m². The smell during drying was unreal—like fruit punch and cookies. After a 3-week cure, the smoke was smooth, flavorful, and perfectly balanced: relaxed but alert, creative but grounded. I’ve since recommended it to five friends—all got similar results. If you want a no-stress, high-reward auto, this is it. Pair it with Alga Grow Plagron for even greener growth, and finish with HESI Power Zyme for cleaner roots and better resin. This strain is a game-changer.