Knockout by Happy Valley Genetics is a high-powered, balanced hybrid that lives up to its name on potency. From XXX x End Game #3, it carries a very high 23-27% THC and a sweet, citrusy, piney, candy flavor, with an uplifting, energetic, talkative effect that works both day and night. It yields heavily, thrives in warm climates, and rewards growers who want a dynamic, flavorful plant with real punch.
This is a feminized photoperiod strain, not an autoflower, so it flowers when you shorten the light cycle and gives you full control over veg length, training, and cloning. The figures below are Happy Valley Genetics breeder values; check your own pack for the exact numbers.
Recommended Strains
Knockout
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THC | 23% - 27% (High) |
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Lineage | XXX x End Game #3 |
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Type | Feminized |
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Height | 5.58 ft | 1.7 m |
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Yield | High |
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Yield Indoor | 1.97 - 2.29 oz/ft² | 600 - 700 g/m² |
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Flowering Time | 9 - 10 weeks |
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Phenotype | 45% Indica / 55% Sativa |
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Effects | Uplifted, Energetic, Talkative |
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Flavors | Sweet, Citrus, Pine, Candy |
Amg
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THC | 22% - 23% (Medium) |
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Lineage | Amnesia x Mexican Haze |
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Type | Feminized |
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Height | 5.58 ft | 1.7 m |
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Yield | High |
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Yield Indoor | 1.47 - 1.64 oz/ft² | 450 - 500 g/m² |
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Yield Outdoor | 19.4 - 21.16 oz/plant | 550 - 600 g/plant |
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Flowering Time | 10 - 11 weeks |
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Phenotype | 20% Indica / 80% Sativa |
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Effects | Balanced, Focused, Relaxed |
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Flavors | Citrus, Earthy |
Knockout Grow Info
| Trait | Knockout (Happy Valley Genetics) |
| Genetics | XXX x End Game #3 |
| Seed type | Feminized photoperiod |
| Genetic profile | 45% indica / 55% sativa |
| THC | 23-27% (very high) |
| Flowering time | 9-10 weeks |
| Height | Around 1.7 m |
| Indoor yield | High, around 600-700 g/m² |
| Outdoor yield | Not published; high (see note) |
| Effects | Uplifted, energetic, talkative |
| Flavor | Sweet, citrus, pine, candy |
These are Happy Valley Genetics’ published figures for the Knockout line at Growlantis. The profile does not list an outdoor yield; it is described as high-yielding. Check the specification on your own Knockout seed pack.
What Makes Knockout Worth Growing
Knockout combines strength, flavor, and versatility. The very high 23-27% THC delivers a potent, knockout-level punch, but the effect is uplifting, energetic, and talkative rather than purely sedative, making it genuinely versatile for day or night use. The sweet, citrus, pine, and candy flavor is a crowd-pleaser, lively and moreish.
For the grower, it is productive and rewarding. It yields a high 600-700 g/m² indoors, finishes in a reasonable 9-10 weeks, and thrives in warm climates. Its balanced structure and strong performance make it a dynamic, satisfying grow for anyone wanting a flavorful hybrid that hits hard.
Is Knockout Indica or Sativa?
Knockout is a balanced hybrid leaning slightly sativa, listed at 55% sativa and 45% indica, from XXX crossed with End Game #3.
That near-even split gives it broad appeal. The effect leans to the uplifting, energetic, talkative side, suiting daytime and social use, but with enough balance to enjoy in the evening too. The plant has a medium, semi-stretchy hybrid structure that stays manageable with light training.
Flowering Time vs Full Grow Time
Because Knockout is a photoperiod strain, these two numbers are separate, and mixing them up is the most common planning mistake.
- Flowering time: 9-10 weeks. This is the bloom stage, which starts only when you switch the lights to 12/12 indoors (or when days shorten outdoors).
- Full grow time (seed to harvest): flowering plus however long you veg. Indoors, a typical grow runs around 4.5 to 5 months from seed, depending on veg length.
The practical point: you control the total time by choosing your veg length. A longer veg means a bigger plant and harvest; a shorter veg gets you there faster. Outdoors, expect to finish around early to mid October.
Does Knockout Need a 12/12 Light Cycle?
Yes. Knockout is a photoperiod strain, so indoors it needs a 12/12 light cycle (12 hours on, 12 hours off) to start and maintain flowering.
Keep it on a long veg schedule, usually 18/6, for as long as you want it to grow, then flip to 12/12 when it has the size and shape you want. Account for the hybrid stretch and flip while the plant is under your height limit. Outdoors, shortening late-summer days trigger flowering naturally.
Knockout Grow Timeline, Week by Week
Treat this as a development pattern, not a fixed schedule, since veg length is up to you.
- Weeks 1-2: germination and seedling. The taproot and first true leaves establish. Keep humidity up and feeding minimal.
- Weeks 3-6: vegetative growth (your choice). The plant builds its frame under 18/6. This is when you top and train.
- Week 0 of flower: the flip. Switch to 12/12. Expect a moderate stretch.
- Weeks 1-3 of flower: stretch and bud set. Vertical growth finishes and flower sites form.
- Weeks 4-8 of flower: bud development. Resinous buds fill out and the sweet, citrusy aroma builds.
- Weeks 9-10 of flower: ripening and harvest. Judge by trichomes, not the calendar.
Choosing Your Setup: Space, Light and Pots
Knockout reaches around 1.7 m with a moderate stretch, so flip to 12/12 while it is comfortably under your height limit. Low stress training or a SCROG net keeps the canopy even and lifts the high yield.
Give it strong light to back the very high THC and dense buds. A full-spectrum LED at 30-40 watts per square foot over the flowering canopy keeps the colas tight. Add a good inline exhaust fan and a carbon filter, since the sweet, citrusy aroma is noticeable in flower.
For pots, 3-5 gallon containers suit most indoor grows, scaled to veg time and plant size. Fabric pots improve root airflow and help prevent overwatering.
Germinating and Raising Seedlings
The paper towel method is the simple, reliable start. Soak the seeds for 12-24 hours, then place them between damp paper towels on a covered plate, kept dark and warm at 70-85°F (21-29°C). A taproot usually appears within two to three days.
When the taproot reaches about 1-2 cm, plant it root-down a knuckle deep in a light mix and keep the surface moist until the seedling emerges. Hold off on nutrients at this stage. New to growing? Our beginner growing guides cover germination step by step.
The Vegetative Stage, Topping and Training
Veg is where you shape a photoperiod plant, and Knockout responds well to training. Keep it under 18/6 with a nitrogen-rich feed and build a strong, even frame before you flower.
Topping the main stem early encourages multiple colas and a wider, flatter canopy, which helps manage the stretch and spread the high yield. Combine it with low stress training or a SCROG net to expose more bud sites to light. Finish training before the flip. You can also clone a plant you like before flowering to preserve its genetics.
Feeding and Watering Knockout
Feed to the stage. Use a nitrogen-forward base through veg, then move to a bloom formula higher in phosphorus and potassium once you flip to 12/12 and buds form. A potent, high-yielding hybrid handles a solid feed, but start moderate and increase based on how the plant responds rather than overfeeding early.
Water by root-zone moisture, not a timetable. Let the top inch or two of medium dry between waterings, then water thoroughly until a little drains. Fabric pots and this water-to-weight habit keep the roots healthy and prevent overwatering.
Flowering and Knowing When to Harvest
Once you flip to 12/12, expect a moderate stretch, then resinous buds fill out over the 9-10 week bloom. The sweet, citrus, pine, and candy aroma develops, so keep air moving and run a carbon filter indoors.
Let ripeness, not the calendar, decide the harvest. Check the trichomes under a loupe and cut when most are cloudy, keeping it earlier for the clearer, more energetic effect or later with some amber for a heavier one. After harvest, hang the branches in the dark at about 60°F (15-16°C) and 55-60% humidity for 7-14 days, then cure in sealed jars, burping daily for the first couple of weeks to protect the candy-citrus flavor.
Growing Indoors vs Outdoors
Indoors, Knockout rewards control. Hold 18/6 for veg, flip to 12/12, train the canopy even, and the high 600-700 g/m² yield is very reachable under strong light.
Outdoors, it thrives in warm climates and is a strong producer, usually finishing around early to mid October. The profile does not publish an exact outdoor figure, but it is described as high-yielding, so expect a generous harvest in good sun. Give it full sun, rich well-draining soil, and airflow around the dense buds.
How Tall and How Much? Height and Yield
Height is easy to plan for. Knockout reaches around 1.7 m with a moderate stretch, so flip early enough and train to keep the final canopy within your space.
On yield it is a strong indoor producer at a high 600-700 g/m². Its outdoor figure is not published but is described as high, so a sunny outdoor grow should be generous. Strong light, a topped or SCROG canopy, and a healthy root zone are what turn that potential into real weight.
Best US Climates for Knockout
Knockout thrives in warm climates, so growers in California, the Southwest, and the warm South and West are ideal, taking it to an early-to-mid October finish outdoors. Its 9-10 week flower also makes it workable in slightly cooler, shorter-season states with a timely finish.
Its preference for warmth means that in cooler or very damp regions, indoor growing where you control the environment is the safer bet. In the humid Southeast, keep airflow strong around the dense buds. For more options, browse our full how-to-grow guide library.
Common Problems When Growing Knockout
A few predictable issues are easy to head off.
Underestimating the stretch
Like most hybrids, Knockout stretches after the flip. Switch to 12/12 while the plant is well under your height limit and train to keep the canopy even.
Overfeeding a vigorous plant
Its vigor can tempt you to overfeed. Start moderate and increase based on the plant’s response, watching the leaf tips for signs of nutrient burn.
Growing it cold
It prefers warmth, so cold, damp conditions can slow it and invite problems. Keep temperatures comfortable, and favor indoor growing in cooler climates.
Harvesting by the calendar
The 9-10 week window is a guide, not a cutting date. Read the trichomes and pistils before you cut, since phenotype and environment shift the timing.
Making the Most of Your Harvest
Do not waste the trim. The resinous sugar leaves make good bubble hash, dry sift, or infused oil that keeps the sweet, candy-citrus character. The stems, roots, and fan leaves compost well and feed your next grow.
Is Knockout Right for You?
If you want a very high-THC, flavorful hybrid with an uplifting, versatile effect and heavy yields, yes. Its balance makes it enjoyable day or night, and its warm-climate vigor and candy-citrus flavor make it a dynamic, rewarding grow. If you need a cold-hardy or ultra-compact plant, look elsewhere. Browse our full how-to-grow guide library for more.
Frequently Asked Questions
Is Knockout indica or sativa?
Knockout is a balanced hybrid leaning slightly sativa, listed at 55% sativa and 45% indica, from XXX crossed with End Game #3. The effect leans uplifting, energetic, and talkative, suiting daytime and social use, but with enough balance to enjoy in the evening. The plant has a medium, manageable hybrid structure.
Does Knockout need a 12/12 light cycle?
Yes. Knockout is a photoperiod strain, so indoors it needs a 12/12 light cycle to start and maintain flowering. Keep it on 18/6 during veg for as long as you want it to grow, then flip to 12/12 when it has the right size. Outdoors, shortening late-summer days trigger flowering naturally.
How long does Knockout take to grow?
Knockout flowers in 9 to 10 weeks once you switch to 12/12. Total seed-to-harvest time depends on your veg length, usually around 4.5 to 5 months indoors. Outdoors it finishes around early to mid October. Judge the finish by trichome maturity rather than the calendar, as conditions shift it.
How much does Knockout yield?
Knockout is a high yielder, producing around 600 to 700 g/m2 indoors. The profile does not publish an outdoor figure, but it is described as high-yielding, so a sunny outdoor grow should be generous. Strong light, a topped or SCROG canopy, and a healthy root zone are what turn that potential into real weight.
How strong is Knockout?
Knockout is very potent at 23 to 27% THC, delivering a knockout-level punch. The effect, though, is uplifting, energetic, and talkative rather than purely sedative, making it versatile for day or night. Its strength suits experienced users, and the sweet candy-citrus flavor adds to a lively, enjoyable experience.
Is Knockout the same as Knockout Runtz?
Not according to its profile. This Knockout, from Happy Valley Genetics, is bred from XXX x End Game #3, with no Runtz in the listed lineage. Searches for “Knockout Runtz” may reflect similar names or associations, so check the specific breeder and genetics on the pack to be sure you have the strain you want.
Can you clone Knockout?
Yes. As a photoperiod strain, Knockout clones well. Take a cutting from a healthy plant in veg, root it, and keep it under 18/6 light. Cloning lets you preserve a plant you like and run repeatable harvests without buying new seeds each time, which autoflowers cannot do.
