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
Puna Budder
Puna Budder Auto cannabis seeds for UK growers. Indica · 18% THC · relaxed, euphoric, creative. Discreet UK delivery, priced in GBP.
- Relaxed
- Euphoric
- Creative
Allen Wrench
Allen Wrench Feminised seeds. A sativa cultivar at 23% THC delivering focused, happy, uplifted. Grow figures from named sources.
- Focused
- Happy
- Uplifted
Champagne Kush
Champagne Kush Feminised seeds. A hybrid cultivar at 15% THC delivering happy, talkative, uplifted. Grow figures from named sources.
- Happy
- Talkative
- Uplifted
CBD PH Haze
Grow CBD PH Haze Feminised in the UK. Cbd genetics at 7% THC, known for euphoric, creative, energetic effects.
- Euphoric
- Creative
- Energetic
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.
Bud rot is the most common reason a UK outdoor crop is lost, and it takes hold when humidity sits high for days on end while dense flower is finishing. The answer is genetics with an open bud structure (Critical Mass, Northern Lights Auto), a canopy thinned enough to keep air moving, and a calendar that brings harvest in before the autumn rain settles. Climate-appropriate genetics paired with a tweaked schedule do the work no fertiliser could.
Read further
Feminised seeds explained
How 99.9% female is bred, and what it changes about your grow.
Autoflowers, start to finish
Ruderalis genetics, the eight-to-twelve week clock, and where they suit a UK grow.
Growing outdoors in Britain
The April-to-October window, the wet finish, and which genetics survive it.
Finishing before the weather turns
Why flowering time and bud structure decide a UK outdoor crop.
Potency, and choosing by outcome
What pushes a strain past 25%, and when a lower number is the better buy.
Where our grow figures come from
Sourced flowering times on about 90% of the catalogue, and what we print when nothing is published.
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.
X-Wing
X-Wing Feminised seeds. A indica cultivar at 26% THC delivering relaxed, sleepy, happy. Grow figures from named sources.
- Relaxed
- Sleepy
- Happy
A-Train
A-Train Feminised seeds. A indica cultivar at 21% THC delivering relaxed, sleepy, happy. Grow figures from named sources.
- Relaxed
- Sleepy
- Happy
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.
Puna Budder
Puna Budder Auto cannabis seeds for UK growers. Indica · 18% THC · relaxed, euphoric, creative. Discreet UK delivery, priced in GBP.
- Relaxed
- Euphoric
- Creative
Crown OG
Crown OG Auto seeds. A indica cultivar at 20% THC delivering euphoric, creative, calm. Grow figures from named sources.
- Euphoric
- Creative
- Calm
Purple Star
Grow Purple Star Auto in the UK. Indica genetics at 10% THC, known for relaxed, sleepy, happy effects.
- Relaxed
- Sleepy
- Happy
Godfather OG
Godfather OG Auto cannabis seeds for UK growers. Hybrid · 25% THC · euphoric, relaxed, sleepy. Discreet UK delivery, priced in GBP.
- Euphoric
- Relaxed
- Sleepy
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 local season length. Northern Britain and Scotland 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 Regions
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.
UK-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 throughout the United Kingdom with tracked delivery and a germination guarantee built on real testing data. Same-day dispatch on orders placed before 2 PM UK time.
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.