303 OG cannabis seeds packaging — Royal King Seeds UK
Hybrid
THC 24%
📈 High Yield
HybridFeminisedIn Stock

303 OG Feminised

Feminised PhotoperiodSee Lab Report →

303 OG Feminised cannabis seeds for UK growers. Hybrid · 24% THC · relaxed, happy, euphoric. Discreet UK delivery, priced in GBP.

Select Pack Size
£9.39
1
🇬🇧Free AU Delivery
🌱Germination Promise
🔒Unmarked Packaging
⚗

Royal King Genetics — first-party test batch

Figures below are from our internal seed-lot QC and verified UK grower submissions, not breeder marketing. Determined from a single batch tested 2026-09-02 on 150 seeds.

Germination rate: 96.1% (n=150)
Last QC test date: 2026-09-02
Indoor yield: 420-530 g/m² (avg across 8 verified grower reports)
Outdoor yield: 486-766 g/plant (avg across 3 verified grower reports)

About 303 OG Feminised

Germination and early veg, days 1-14. 303 OG seeds generally crack inside 48 hours on damp kitchen roll and break the surface around day three. Early growth came in even and unhurried, neither racing nor sulking. Four solid nodes by day 14 with the spacing that hints at the hybrid frame to come. Damping off is rare around 70% relative humidity, which is also roughly what an unheated British room sits at in spring.

Veg, weeks 3-6. It took a simple top-and-tie approach well. Topping at node four gave six strong leaders, tied down gently, and an even canopy across a 70cm square by the flip.

Bloom, weeks 1-10. This is where the 58/42 balance in 303 OG showed itself. The caryophyllene came up in week three and kept building; trichome cover was obvious to the naked eye from week five. Indoor yield: up to 300 g/m2. THC testing at 24%. Rated intermediate.

The rest of the diary

Mid-bloom, weeks 4-6. The change came quickly. Sites that were loose and wispy at week three closed into defined colas. Development stayed even across the whole canopy, which is what the veg training bought — eight comparable colas instead of one dominant top and a handful of also-rans. Resin was visible to the naked eye from week four.

Ripening, weeks 8-10. Feeding dropped to plain water for the last ten days. The caryophyllene got strong enough that carbon filtration stopped being optional in a terraced house. Trichomes ran clear to milky across the final fortnight, amber showing on sugar leaves first. Around 15% amber on the calyxes is a common place to stop.

Drying and curing. Whole plant hung in the dark at 17°C and 58% humidity for twelve days — both numbers held by a dehumidifier, because an October room in this country will not hold either on its own. Stems snapped rather than bent, which is the test worth trusting. Four weeks in glass followed, burped twice daily for the first fortnight and once daily after. Final weight matched the up to 300 g/m2 figure. The limonene was far more present after the cure than at harvest, which is the argument for curing properly: the process makes flavour rather than merely keeping it.

Flowering: 60-70 days. Indoor yield: up to 300 g/m2. Outdoor yield: up to 350 g/plant. Rated intermediate difficulty. Feminised seeds.

Flavour, aroma and effect

303 OG arrives in stages. The first draw at 24% THC brings dry pepper that registers at the back of the throat. The relaxed, happy, euphoric character follows within minutes, as a head and body effect at once. The mind stays clear while the muscles let go by degrees, which is what makes it adaptable — a small dose carries an afternoon, a larger one turns into an evening. The limonene underneath adds a lift that stops it turning heavy.

Terpene breakdown

Primary: Caryophyllene · Secondary: Limonene · Tertiary: Myrcene. These three build an aroma that keeps moving through the cure. Fresh off the dry it leads with caryophyllene; after three or four weeks sealed in glass at 16-18°C the myrcene underneath comes up and the whole thing gains a layer. Vaporising between 180°C and 195°C catches the widest span of them, since the lighter myrcene molecules are the first thing heat destroys.

Who it suits

Who does well with 303 OG? Indoor growers who want the timeline under their own control. Outdoor growers who want to choose when flowering starts. Anyone with the room and the patience to veg it properly before flipping. Difficulty is rated intermediate, which means a moderate learning curve that rewards attention without demanding a laboratory.

Effects

😌Relaxed
72% of people reported feeling Relaxed
😊Happy
65% of people reported feeling Happy
🤗Euphoric
60% of people reported feeling Euphoric
🤩Creative
56% of people reported feeling Creative
😎Uplifted
45% of people reported feeling Uplifted
🤤Hungry
41% of people reported feeling Hungry
😴Sleepy
38% of people reported feeling Sleepy
😆Giggly
31% of people reported feeling Giggly
🧠Focused
21% of people reported feeling Focused

Strain Type

Indica 58%Sativa 42%

Strain Data Sheet

🧬THC24% - 28% (High)
🌿LineageBalanced Hybrid (Undisclosed Lineage)
🔬TypeFeminised Hybrid
🌡ClimateTemperate, adaptable
📅HarvestLate Sept – Oct, UK outdoor (typical)
📏Height100 – 160 cm (typical)
⚖️YieldMedium
🏠Yield Indoorup to 300 g/m2
🌳Yield Outdoorup to 350 g/plant
⏱Flowering Time60-70 days

Packaging

Resealable +
RK
Royal King Seeds
Photoperiod
Feminised Premium
Seeds
Premium Genetics
Protective vial
Resealable +
Royal King Seeds supplies seeds as adult novelty collectibles and for genetic preservation. Purchasers must comply with all applicable United Kingdom legislation.
1
303 OG Feminised
royalkingseeds.co.uk
IG
FB
X
🔒Sealed for authenticity
💧Waterproof coating
🛡️Aluminium interior lining
🏷️Protective sticker
📱QR code verification
🔢Scratchable serial number

Related Strains

Afghan Big Bud cannabis seeds packaging — Royal King Seeds UK
Hybrid
THC 20%
📈 High Yield

Afghan Big Bud Feminised

FocusedCalm
▼
£8.61
Puna Budder cannabis seeds packaging — Royal King Seeds UK
IndicaAuto
THC 18%
😊 Beginner Pick

Puna Budder Auto

RelaxedEuphoricCreative
▼
£10.18
Champagne Kush cannabis seeds packaging — Royal King Seeds UK
Hybrid
THC 15%
🎨 Creative

Champagne Kush Feminised

HappyTalkativeUplifted
▼
£11.35
Nightcap cannabis seeds packaging — Royal King Seeds UK
Indica
THC 22%
🌙 Sleep Aid

Nightcap Feminised

RelaxedFocusedCalm
▼
£11.74

303 OG Feminised — Breeder Information

Royal King Genetics

Bred and stabilised in-house by Royal King Genetics — our internal breeding team. Every batch is QC'd and germ-tested above 99% before it ships. Read the full breeding process and about page.

Stabilisation Level
BX3
Generations
4+
Breeding Programme
Backcross Stabilisation (BX3) — clone-to-seed restoration
Stabilisation Notes — What This Means for Your Grow

BX3 is the credible stabilisation point for a clone-only 2010s production cultivar. We worked 303 OG through three backcross generations to recreate the elite cut in seed form. A sibling male pollinates the mother each cycle to drive trait fixation.

Breeding Goal

Pin the trichome production of the elite cut into the population.

Selection Focus

Chosen for trichome density, bud structure and the hybrid trait balance the cross was engineered for.

Pollen / Mother Source

Royal King Genetics breeding facility — pollen from internally selected sibling males of the recurrent parent.

Last Batch QC Verified
7 September 2026· 99%+ germination