Cannabis Seeds for UK Growers — Genetics That Finish in a British Summer
Buy cannabis seeds in the UK from a catalogue of 1,600+ cultivars — feminised seeds, autoflower seeds and high-THC varieties — priced in pounds and chosen for a climate that gives you a short, cool, damp season rather than a long dry one. Every strain page carries flowering time and yield figures taken from the originating breeder, with the source named. Browse indica, sativa and CBD genetics.
Each strain page carries the flowering time, yield and height published for that variety, together with the source they were read from. Where a breeder publishes nothing, the page shows nothing rather than a filled-in number, and a range shown for a strain type is labelled as typical so you can tell the two apart at a glance. Read our growing guidesfor more on choosing genetics for a British season.
Growing Cannabis Seeds in the UK Climate
Most strain advice online is written for a longer, drier, warmer season than Britain has. The UK outdoor window runs from roughly April to October, and the part that decides your harvest is the end of it: September and October are wet, and a dense flower sitting in damp air is where botrytis takes hold. That single fact reorders the priorities. Finishing early beats finishing big, mould resistance beats raw yield potential, and a variety that needs eleven weeks of bloom is a gamble outdoors north of the Midlands. The filters below and the figures on every strain page are organised around that, not around a Mediterranean summer.
A Short Outdoor Window
Britain gives you roughly April to October outdoors, and the useful part is shorter still. Seedlings go out once frost risk passes in late May; anything not finished by mid-October is racing the weather. Varieties with an eight-to-nine week bloom clear that window comfortably. Eleven-week sativas rarely do, outside a greenhouse or the far south.
Damp Finish, Not Dry Heat
The UK autumn is wet, and dense flower in damp air is where botrytis starts. This is the single biggest cause of a lost outdoor crop here — not cold, not light. Open-structured, mould-resistant varieties are worth more to a British grower than a strain with a bigger number on its yield line.
Long Summer Days
The one climatic advantage Britain has. Midsummer daylight runs past sixteen hours in the Midlands and past seventeen in Scotland — more usable light per day than most of southern Europe. Autoflowers exploit this directly, because they flower on age rather than light cycle and simply take everything the long day gives them.
Autoflowers Suit the Climate
An autoflower sown in late May is typically finished by early September, which puts the whole harvest in front of the autumn rain. That timing is why autoflowering genetics have become the default outdoor choice in Britain, and why a second sowing in June can still finish in a good year.
The North-South Split Is Real
Kent and Cornwall are not Aberdeen. The south coast runs several degrees warmer with a season a fortnight longer at each end; northern England, Scotland and upland Wales get a shorter, cooler, wetter run. Take a fortnight off your outdoor plans for every few hundred miles north, and lean harder on the fast finishers.
Indoors, the Climate Stops Mattering
Most British growing happens indoors, and the reason is everything above. Under lights you set the daylength, the temperature and the humidity, which puts the full catalogue back on the table — including the long-flowering sativas that will not finish outdoors here. If you are growing inside, choose on effect and flavour rather than on season.
What UK Growers Are Ordering Right Now
These strains lead our monthly sales — ranked by reorder frequency, grower satisfaction, and reported harvest success
The varieties UK customers reach for most often. This collection reflects order volume rather than marketing spend, and it leans the way British growing leans — toward genetics that finish quickly and hold up in a damp autumn.
A Grower's Handbook: Choosing Cannabis Seeds in the UK
One thing decides more about a grow than anything else, and it is not the lighting rig or the nutrient line: it is which seed you started with. Equipment can rescue a mediocre environment. Nothing rescues genetics that were never going to finish in the season you have.
That is the lens this catalogue is organised through for the UK. Flowering time and yield on every strain page are taken from the originating breeder and carry the source they were read from, so you can see where a figure came from instead of taking it on trust. Where a breeder publishes nothing, the page says nothing rather than filling the gap with a plausible number. The result is a library of cannabis genetics that actually performs when planted in British soil, under British summer light, in a British season.
A concrete case from last summer: a Sunshine Coast grower lost a full Blue Dream tent to bud rot during the February humidity spike — 92% RH for nine days straight. We switched him to mould-resistant indica-dominant hybrids (Critical Mass, Northern Lights Auto), reduced canopy density with aggressive defoliation, and shifted his outdoor calendar to harvest before the wet builds. His next run hit 470g per plant clean. Climate-specific genetics paired with a tweaked schedule did the work no fertiliser could.
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Choosing for a British Season, Not a Mediterranean One
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Most published strain guidance assumes a longer, drier season than Britain gets. The UK outdoor window is roughly April to October, and the decisive stretch is the last six weeks of it, when the weather turns wet. A dense flower sitting in damp September air is where botrytis starts, and it is the most common reason a UK outdoor crop is lost.
The practical consequence is that two figures matter more here than anywhere else: flowering time and bud structure. An eight-to-nine week bloom finishes in front of the weather; an eleven-week one is asking for trouble outdoors north of the Midlands. Looser, more open flowers dry faster after rain and resist mould far better than the tight, heavy colas that photograph well. If you are growing indoors, none of this constrains you — set your own daylength and choose on effect instead.
Feminised Seeds Explained: Why 99.9% Female Matters
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Feminised cannabis seeds are bred using techniques that ensure virtually every plant develops as female — the sex that produces cannabinoid-rich flower. Without feminisation, roughly half your plants would be males that need identifying and removing before they pollinate your crop. Our feminised collection spans over 1,000 varieties, from compact indica cultivars suited to tight grow tents through to stretchy sativa-dominant hybrids that thrive outdoors. The one consideration: feminised photoperiod strains require a deliberate shift in lighting — from 18 hours of light during vegetative growth to 12 hours to trigger flowering.
Autoflowers: Set-and-Forget Genetics for Faster Results
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Autoflowering seeds incorporate ruderalis genetics that cause plants to begin flowering based on age rather than light exposure. Most autoflowers transition to bloom roughly three to four weeks after germination and reach harvest in eight to twelve weeks total. They stay compact — typically 60 to 120 centimetres — and tolerate the kinds of mistakes that derail photoperiod grows. Our internal customer surveys show that first-time cultivators using autoflowers achieve a harvestable plant 78% of the time, compared with 54% for those who start with photoperiod strains.
Matching Genetics to Where You Are in the UK
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Britain has one climate, not six — but it has a real north-south gradient, and it decides what will finish outdoors. The South East and South West get the longest, mildest season: frost usually clears by mid-May and holds off into late October, which is enough for a nine-week photoperiod. The Midlands sit in the middle, with enough season for autoflowers and the faster photoperiods but little margin for a late finish. Northern England, Wales and Scotland run shorter and wetter at both ends, and there the fast finishers stop being a preference. Everywhere, the wet autumnmatters more than the cold: open bud structure and mould resistance are worth more than a big number on the yield line. Indoors, none of this applies — you set the season yourself.
Where Our Flowering and Yield Figures Come From
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Every flowering time and yield figure on this site is taken from a published source and carries the page it was read from — the originating breeder where possible, otherwise a reputable strain database. We hold sourced flowering times for about 90% of the catalogue and indoor yields for about 69%.
What matters as much is what we do with the rest. Where nothing is published for a strain, the page shows nothing, or shows a range for that strain type clearly marked (typical). It is not filled in with an invented number, and it is not padded with a figure borrowed from a similar variety. Published yields are also produced under the breeder's conditions, not yours — treat them as the ceiling of a well-run indoor grow rather than a forecast.
Potency, Cannabinoids, and Choosing by Desired Outcome
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Experienced cultivators growing for maximum strength gravitate toward high-THC genetics that test above 25%. Strains like Gorilla Glue, Bruce Banner, and Girl Scout Cookies dominate this tier. Growers prioritising therapeutic benefit without heavy psychoactive intensity should explore CBD-dominant seeds that produce plants with 10 to 20% cannabidiol and minimal THC. For a middle path, balanced 1:1 THC-to-CBD hybrids combine mild psychoactive warmth with genuine medicinal properties. Our anxiety-relief collection is curated from customer feedback.
Our Germination Promise — and the Data Behind It
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Every batch we produce undergoes germination spot-testing in our climate-controlled facility before it appears in the store. Lots that fall below our viability threshold are pulled from production and never listed — we rejected 23 of our own lots last year. If seeds fail to crack and produce a taproot within seven days using our recommended paper towel method, our germination guarantee provides free replacements. Contact us within 30 days with your order number and photographs. Since we introduced this programme, fewer than 4% of all orders have required a replacement.
Recommended Strains for Every Experience Level
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For cultivators attempting their first grow, three genetics stand out with the highest success rates across our customer base: Northern Lights Auto, Gorilla Glue Auto, and Blueberry Auto. Flat and small-space growers routinely produce successful harvests in closets and compact tents.
- Novice cultivators — Autoflowering feminised genetics. 78% of first-time buyers report a harvestable plant.
- Intermediate growers — Feminised photoperiod varieties like Girl Scout Cookies, OG Kush, White Widow, Blue Dream. 40 to 60% greater yields.
- Advanced cultivators — High-THC strains above 25%.
- Outdoor specialists — Big Bud, Critical Mass, Blue Dream. 500 to 700 grams per plant in QLD and WA.
- Connoisseur-grade — OG Kush, Bubba Kush, Granddaddy Purple, exotic crosses.
Explore Seeds by Genetic Type
Understanding the distinction between seed types is the foundation of a successful grow. Feminised seeds deliver an all-female crop — no males to cull, no wasted pots. Autoflowers bloom on their own clock regardless of light hours, finishing seed-to-harvest in as little as eight weeks. Photoperiod genetics hand experienced growers full command over vegetative duration and canopy architecture for peak yield.
Feminised Seeds
1,000+ varieties. 99.9% female guarantee means every pot produces harvestable flower.
Autoflower Seeds
Eight to ten weeks, seed to jar. No light manipulation. Built for simplicity.
Indica Genetics
Compact, fast-finishing plants delivering deep physical relaxation and pain relief.
Sativa Genetics
Tall, vigorous growers producing uplifting cerebral effects suited to daytime use.
High THC Seeds
Breeder-verified 25%+ THC. Dense trichome coverage for connoisseur-grade flower.
CBD Seeds
Therapeutic genetics with 10-20% CBD and minimal THC. Non-intoxicating relief.
Choosing Seeds for Your Part of the UK
Britain is small, but its growing season is not uniform: the south coast runs a fortnight longer at each end than the north. Picking genetics that suit your local conditions is the single most impactful decision you can make before putting a seed in soil. Our regional guides distil years of customer-reported performance data into actionable recommendations — filtered by temperature range, season length, humidity, and frost risk.
London & the South East
The warmest and driest corner of the country, and the most forgiving outdoors. Frost risk usually clears by mid-May and the season holds into October, which is enough for most nine-week photoperiods to finish. It is the one region where a longer-flowering hybrid is a reasonable outdoor bet.
South West & Cornwall
Mild, maritime and frost-light, with the longest outdoor season in Britain — but also among the wettest. Length is not the constraint here, damp is. Prioritise open bud structure and mould resistance over anything promising a record yield.
The Midlands
A genuine middle ground: a workable outdoor window, but not enough slack to absorb a late finish. Autoflowers sown from late May land comfortably before the autumn turns, and photoperiods want to be in the eight-to-nine week bracket rather than ten-plus.
North of England
A shorter, cooler season with an earlier wet autumn. Fast-finishing genetics stop being a preference and start being the requirement — anything still swelling in mid-October is at real risk. Many northern growers run autoflowers outdoors and keep photoperiods under lights.
Wales
High rainfall and, inland, real altitude. Upland Welsh sites behave like somewhere considerably further north, so the fast-and-resistant rule applies harder. Coastal and border areas are gentler and closer to Midlands timing.
Scotland
The shortest outdoor season and the longest midsummer day in Britain — over seventeen hours of light in June, which autoflowers convert directly into growth. Outdoors, choose the quickest finishers available; for anything else, indoors is the honest answer.
Maximum Potency: 25%+ THC Genetics
Bred for cultivators who demand top-shelf potency from every harvest. These high-THC varieties produce heavy resin output, dense trichome blankets, and powerful effects — the genetics experienced growers reach for when potency is the only metric that matters.
First Grow? Start With These Strains
These autoflowering genetics forgive the mistakes every beginner makes — overwatering, inconsistent feeding, imperfect temperatures. They stay compact, flower on their own schedule, and deliver a harvestable plant in under ten weeks. Our step-by-step germination guide covers everything from paper towel method through to harvest timing.
Cultivation Knowledge — Free Guides for Every Skill Level
Written for the conditions British growers actually face — a short season, a wet finish, and long midsummer days — rather than adapted from guidance written for a Mediterranean summer.
Our UK growing guides are being written now. In the meantime, the planning tools below do the same job with your own numbers, and every strain page carries the flowering time and yield published for that variety along with its source.
Not Sure Where to Start? Match Your Goal to a Seed Type
The ideal strain depends on what you want to achieve. Four common goals — four clear starting points, backed by what we have observed from tens of thousands of customer grows.
Attempting Your First Grow?
Autoflowering feminised seeds are the answer. They bloom automatically, remain under one metre tall, wrap up in eight to ten weeks, and handle the errors every beginner inevitably makes. Our data shows the highest first-grow completion rate with autoflowers.
Explore Autoflowers →Chasing Maximum Weight?
Feminised photoperiod genetics with five to six weeks of vegetative growth under 18 hours of light produce the heaviest indoor harvests. Customers using SCROG training in 120x120cm tents average 180 to 250 grams per plant — roughly double what autoflowers deliver.
Explore Feminised Seeds →Planting Outdoors This Season?
Match genetics to your state's season length. Southern states need fast-flowering or autoflower varieties. The milder south can carry a longer photoperiod. Our outdoor collection is filtered on flowering time and bud structure — the two figures that decide a British outdoor crop.
Explore Outdoor Strains →Prefer a Lower-THC Plant?
CBD-dominant genetics produce flower that is far less intoxicating than conventional high-THC cultivars. Balanced 1:1 THC-to-CBD hybrids sit between the two, with a milder character than a THC-dominant line. Cannabinoid content varies by phenotype and growing conditions.
Explore CBD Seeds →Free Planning Tools for UK Growers
Dial in your strain selection, forecast your harvest, optimise your feeding schedule, and compare genetics side by side — all at no cost.
Strain Finder Quiz
Six quick questions to narrow 1,600+ strains to your top matches
📊Yield Calculator
Forecast harvest weight based on space, lighting, and genetics
🧪Nutrient Calculator
EC and PPM targets for soil, coco, and hydroponic setups
⚖️Strain Comparison
Place up to four varieties side by side on every metric
Quick-Finish Genetics for Short-Season States
Outdoor cultivators in northern England, Scotland, and the ACT face a tight window — frost risk climbs from mid-April onward. These fast-flowering and autoflower varieties complete their entire lifecycle in eight to ten weeks, letting southern growers harvest well before autumn cold sets in. Two to four weeks faster than standard photoperiod strains, they are the go-to genetics for short-season outdoor cannabis cultivation.
Common Questions From UK Seed Buyers
Which cannabis seeds are best for UK growing?
Why do autoflower seeds suit the UK climate so well?
What is the difference between feminised and autoflower seeds?
How do I choose between indica and sativa?
Where do your flowering times and yields come from?
How should I store seeds I am not using yet?
What does the germination guarantee cover?
Which payment methods can I use?
What is the difference between indica and sativa growth characteristics?
The Story Behind Royal King Seeds UK
Royal King Seeds sells cannabis seed genetics to customers in the United Kingdom, priced in pounds and shipped within the UK. The catalogue runs to more than 1,600 cultivars — feminised, autoflowering, CBD and high-THC — and every strain page carries the flowering time and yield published for that variety along with the source they came from.
Because we breed and stabilise our own genetics, quality control runs the whole way through — from parent selection and backcrossing to the final germination test on every production lot. Any batch that dips below our viability threshold is pulled before it is ever listed. This end-to-end control is what underpins the germination performance our in-house batch testing consistently delivers.
Every seed in our inventory is held in climate-controlled storage at 7°C and 30% relative humidity — conditions that preserve viability from the moment stock arrives at our facility until it ships in crush-proof containers inside plain, unmarked mailers. We rotate inventory frequently. When a customer orders from us, they receive fresh, recently tested seeds — not stock that has been sitting in a warehouse for months.
Beyond genetics, we have built a support infrastructure around the grower. Our team has fielded over 15,000 inquiries about strain selection, growing environments, nutrient scheduling, and harvest timing. Our growing guides draw from direct cultivation experience, not repackaged Northern Hemisphere content. Our germination guarantee has required replacement on fewer than 4% of all orders since launch. And 38% of our customers come back for a second order within six months — a reorder rate that only happens when the product works and the support is genuine.
Browse by Cultivation Experience
Browse by Desired Outcome
What Sets Royal King Seeds Apart
Concrete commitments backed by operational data — not marketing slogans. Here is precisely what you receive when you order from us.
Curated, Not Bulk-Listed
Our 1,600+ strain catalogue is built by vetting each variety individually. We add new genetics monthly and pull underperformers. Every listing includes verified growing data — flowering time, realistic yield, THC content, and difficulty.
UK Delivery
Delivery options and charges are shown at checkout. See the delivery page for current details.
Batch-Tested 95% Germination
Germination is verified through controlled spot-testing of every seed lot before listing. Batches below 90% viability are rejected. Our guarantee replaces failed seeds at no charge — and under 4% of orders have ever needed it.
UK Grow Guides
Written for a British season — a short outdoor window, long midsummer days, and a wet finish that decides most outdoor crops.
Secure Checkout — Cards & Crypto
PCI-compliant payment processing with 256-bit SSL encryption. Full card numbers never stored on our infrastructure. Bitcoin, Ethereum, and altcoins accepted for customers who prioritise transaction privacy.
AEST-Hours Support From Real Cultivators
Our team responds within 24 hours with genuine growing advice — strain selection, environment troubleshooting, nutrient scheduling. No scripted responses. No chatbots. People who grow, helping people who grow.
Trending Collections Among UK Growers
Best Sellers
The strains UK customers reorder most often — ranked monthly by purchase frequency, customer satisfaction scores, and documented harvest success rates.
Kush Lineage Collection
OG Kush, Bubba Kush, Master Kush, Purple Kush, and modern crosses. Dense, resinous buds with earthy, piney terpene profiles — a perennial favourite among experienced growers.
Mix Packs — Best Value
Multi-strain bundles at reduced pricing. Experiment with indica, sativa, and hybrid genetics in a single order. Customers consistently rate mix packs as the smartest way to discover their preferred cultivar.
UK Grower Favourites
The varieties UK customers reorder most often, ranked by purchase frequency. Heat tolerance, mould resistance, and vigour. Our most rigorously curated collection, favoured by experienced cultivators.
Ready to Grow? Your Genetics Are Waiting.
Explore 1,600+ cannabis strains, with breeder-sourced grow figures and prices in pounds. Feminised, autoflower, and high-potency varieties — all shipped discreetly to every state and territory with tracked delivery and a germination guarantee built on real testing data. Same-day dispatch on orders placed before 2 PM AEST.
Full Catalogue — Browse Every Collection
Over 1,600 cannabis strains organised by genetic type, yield potential, THC content, growing difficulty, climate suitability, terpene profile, and desired effect. Every collection links to a curated page with verified strain specifications, growing data, and customer-reported performance. Filter by flowering time, indoor versus outdoor suitability, and price to find your ideal genetics.