
Magnum Feminised
Grow Magnum Feminised in the UK. Hybrid genetics at 15% THC, known for focused, calm effects.
Royal King Genetics β 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 2026-09-20 on 225 seeds.
About Magnum Feminised
Where you grow Magnum in Britain matters less than when you start it. This is one temperate maritime climate with a real north-south gradient: the south coast opens and closes its season around a fortnight either side of the central belt or upland Wales. Heat is almost never the constraint here. The wet finish is β rain sitting in dense flower through late September and October is what starts botrytis, and it ends more British outdoor crops than every insect on the plot combined. That puts the 78 days flowering window and the bud structure ahead of everything else on this page. Under lights none of it applies: daylength, temperature and humidity are yours to set, and Magnum can be run anywhere in the country on its merits.
The pressures on a British grow are fairly predictable. Damp is the first of them: botrytis in dense flower from September on, answered with open bud structure and moving air rather than with a spray. Indoors it is spider mite and thrips that arrive, and humidity above 60% in late bloom is what turns a contained problem into a lost room. Outdoors in a wet spring the slugs take more seedlings than every insect put together, and they do it overnight.
Flavour, aroma and effect
Magnum arrives in stages. The first draw at 15% THC brings dry pepper that registers at the back of the throat. The focused, calm 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 β 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 Β· Secondary: Limonene Β· Tertiary: Myrcene. How this profile survives the journey from flower to vapour depends on temperature. Low vaporisation, 180-188Β°C, keeps the limonene and myrcene audible over the caryophyllene base. Run it hotter, or burn it, and the three collapse into one note β pleasant enough, but none of the complexity that made it worth choosing.
Who it suits
Who does well with Magnum? 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
Strain Type
Strain Data Sheet
Packaging
Feminised Premium
Seeds
authenticity
lining
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Magnum Feminised β Breeder Information
Royal King GeneticsBred and stabilised in-house by Royal King Genetics β 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.
Magnum has been progressed through four generations of phenotype hunting and selection. Vigour, bud density and finishing time are all locked across the pack β every plant performs to the spec sheet.
Stabilise the Magnum cross over four selection rounds.
Chosen for vigour, terpene saturation and a tight finish window that allows production planning.
Royal King Genetics select-mother programme β pollen drawn from an internally maintained reversed-female line.