Fastest Growing Cannabis Strains (Seed to Harvest in 8 Weeks)

Time is the most valuable resource for any cannabis grower. Whether you are working with a short outdoor season, trying to squeeze in multiple indoor harvests per year, or simply impatient to enjoy the fruits of your labor, growing speed matters. The good news is that modern cannabis breeding has produced strains that can go from seed to dried, cured bud in as little as 8 to 10 weeks total. In this guide, we cover the fastest-growing cannabis strains available in 2025, explain the science behind quick-finishing genetics, and share tips for shaving days off your harvest timeline. If you are looking for autoflower seeds or fast-version feminized strains, Royal King Seeds USA has one of the largest selections available with fast domestic shipping.

Understanding Fast-Growing Cannabis Genetics

There are two primary categories of fast-growing cannabis: autoflowers and fast-version photoperiods. Autoflowering strains contain Cannabis ruderalis genetics, which cause the plant to begin flowering automatically after about 3–4 weeks of vegetative growth, regardless of the light schedule. This means the entire lifecycle from seed to harvest takes just 8–10 weeks for most autos. Fast-version photoperiod strains, on the other hand, are feminized seeds that have been crossed with autoflower genetics to reduce flowering time by 1–2 weeks compared to the standard version, while still requiring a 12/12 light change to initiate flowering.

Both types offer distinct advantages. Autoflowers are the absolute fastest option and are perfect for beginners (see our beginner strains guide). Fast-version photoperiods offer the yield and potency of traditional feminized strains with a shortened flowering window. You can explore both types in the autoflower category and the feminized category at our USA store.

The 10 Fastest Cannabis Strains in 2025

1. Zkittlez Auto (8–9 Weeks Total)

Zkittlez Auto is one of our fastest-finishing strains, completing its entire lifecycle in just 8–9 weeks from germination. Despite the speed, it delivers impressive 23% THC potency with a candy-sweet flavor profile that has made Zkittlez one of the most popular strain families in cannabis. It stays compact at 60–80cm, making it ideal for small indoor spaces and stealthy outdoor grows. Yields are solid for an auto at 350–450g/m². Available at Royal King Seeds Canada as well.

2. Purple Punch Auto (8–9 Weeks Total)

Purple Punch Autodelivers stunning purple buds in record time. This indica-dominant auto goes from seed to harvest in 8–9 weeks and produces 22% THC with a grape-and-blueberry flavor that tastes as good as it looks. Purple Punch Auto is very forgiving of growing errors, which combined with its speed makes it one of the best choices for impatient beginners. Yields reach 350–400g/m² indoors.

3. Northern Lights Feminized (7–8 Weeks Flowering)

Northern Lights is one of the fastest-flowering photoperiod strains available. With a flowering time of just 7–8 weeks after the light flip, you can go from clone or short veg to finished buds in about 10–11 weeks total. Northern Lights produces 22% THC, is extremely mold-resistant, and yields 400–500g/m² indoors. It is also one of the most beginner-friendly strains ever created. Find it at our Canada store or the Germany store.

4. Critical Mass Feminized (7–8 Weeks Flowering)

Critical Mass combines extreme speed with extreme yield. It flowers in just 7–8 weeks and produces some of the heaviest harvests of any strain, with indoor yields exceeding 500g/m². The buds are so dense and heavy that branches may need support. With 22% THC and a sweet, earthy flavor, Critical Mass is the perfect strain when you need a fast, heavy harvest. For more high-yielding options, check our high-yield seeds guide.

5. Wedding Cake Feminized (8–9 Weeks Flowering)

Wedding Cake finishes flowering in 8–9 weeks, which is fast for a strain that delivers 27% THC. The rich, vanilla-frosting flavor and dense, frosty buds make it a dispensary-grade strain that you can grow at home on a relatively quick turnaround. It is also pest-resistant and beginner-friendly, earning it a spot on our best beginner strains list.

6. White Widow Feminized (8–9 Weeks Flowering)

White Widow finishes flowering in about 8–9 weeks, making the total lifecycle roughly 11–13 weeks from seed when you include vegetative growth. At 25% THC with legendary trichome production, White Widow offers a great balance of speed, potency, and yield. It is one of the most reliable and predictable strains you can grow, which is why it has remained a top seller for over three decades. American growers should check out our USA growing guide for more strain recommendations.

7. OG Kush Feminized (8 Weeks Flowering)

OG Kush is a West Coast icon that finishes flowering in approximately 8 weeks. It delivers 26% THC with that unmistakable earthy, pine, and lemon terpene profile. OG Kush is a moderate-difficulty strain that rewards growers who can maintain consistent conditions, but its fast flowering time makes it a worthwhile pick for intermediate growers looking to speed up their cycle.

8. Gorilla Glue #4 Feminized (8–9 Weeks Flowering)

At 30% THC, Gorilla Glue #4 is one of the most potent strains you can grow, and it finishes in just 8–9 weeks of flowering. The resin production is extraordinary, making it a top choice for extract makers who want fast turnarounds. GG4 produces 450–550g/m² indoors and adapts well to various training methods. Find it in the Canada store too.

9. Runtz Feminized (8–9 Weeks Flowering)

Runtzhas taken the cannabis world by storm with its candy-like flavor and 29% THC potency. It flowers in 8–9 weeks and produces colorful, trichome-coated buds that are as photogenic as they are potent. Runtz is a moderate-difficulty strain that does best in controlled indoor environments but rewards growers with exceptional quality in a reasonable timeframe.

10. Do-Si-Dos Feminized (8–9 Weeks Flowering)

Do-Si-Dosrounds out our fastest strains list with 28% THC and an 8–9 week flowering time. This indica-dominant hybrid produces dense, lime-green buds with lavender accents and a sweet, earthy aroma. It is a solid producer at 400–500g/m² indoors and finishes reliably within its stated timeframe.

Speed Growing Tips: How to Shave Days Off Your Harvest

Choose autoflower genetics. The fastest way to harvest is to grow autoflower seeds. With no need to change the light cycle and a total lifecycle of 8–10 weeks, autos are unbeatable for speed. The Canadian autoflower selection and German store carry the same fast genetics.

Run 20/4 lighting for autos. Autoflowers do not need a dark period to flower, so running 20 hours of light and 4 hours of dark maximizes photosynthesis and growth speed. Some growers run 24/0, but the marginal gains diminish and plants benefit from a short rest period.

Maintain optimal temperatures.Cannabis metabolism slows in cold conditions. Keep your grow room at 75–82°F (24–28°C) during lights-on and no lower than 65°F (18°C) during lights-off. Warmer temps (within reason) accelerate cell division and growth.

Use high-quality LED lighting.Modern full-spectrum LEDs provide the intensity and spectrum that cannabis needs to grow fast. Aim for 400–600 PPFD during vegetative growth and 600–900 PPFD during flowering. More light equals faster growth, up to the point of light stress.

Feed correctly from the start.Under-feeding slows growth. Use a complete cannabis nutrient line at the manufacturer’s recommended doses (start at 50% for seedlings) and ensure your pH is dialed in at 6.0–6.5 for soil or 5.5–6.0 for coco/hydro. Consistent feeding keeps the plant growing at maximum speed.

Consider shorter veg for photoperiods. If you are growing feminized photoperiod seeds, you can flip to 12/12 after just 3–4 weeks of veg to speed up the total timeline. You will sacrifice some yield per plant, but you can compensate by growing more plants in a SOG (sea of green) setup.

Multiple Harvests Per Year with Fast Strains

One of the biggest advantages of growing fast cannabis strains is the ability to run multiple cycles per year. With autoflowers that finish in 8–10 weeks, indoor growers can realistically pull off 4–5 harvests per year from the same grow space. Even outdoor growers in warmer climates can get 2–3 autoflower harvests per season by staggering planting dates. This dramatically increases your annual yield compared to a single photoperiod grow. If maximizing your total harvest weight is the goal, combine fast genetics with high-yielding strains from our high-yield cannabis seeds guide.

For example, running Zkittlez Autoback-to-back could give you five harvests of 350–450g/m² per year, totaling 1,750–2,250g/m² annually. Compare that to a single run of a photoperiod strain yielding 500–600g/m² once, and the math clearly favors fast autoflowers for total annual production.