
XXX 420 Auto
XXX 420 Auto cannabis seeds for Irish growers. Indica strain · 18% THC · relaxed, sleepy, happy. Discreet packaging, nationwide delivery, sourced grow figures.
Royal King Genetics — first-party test batch
Figures below are from our internal seed-lot QC and verified Irish grower submissions, not breeder marketing. Determined from a single batch tested 2026-09-10 on 325 seeds at 21-24°C.
About XXX 420 Auto
XXX 420 carries caryophyllene as its lead note: peppercorn and warm timber, dry rather than sweet, catching slightly at the back of the throat. Myrcene sits beneath it and shows up second, adding weight and body underneath. The plant tests at 18% THC across a 65/35 split, though what decides whether any of this reaches the jar is the cure, not the seed.
Growing it for aroma
Growing XXX 420 for terpene expression and growing it for weight are not the same project, and it is worth deciding which one you are on. The Caryophyllene/Myrcene/Bisabolol profile does its best work in living soil, where the biology produces compounds a bottle does not contain. Good peat-free compost and worm castings are available in any garden centre here, which makes that approach far less specialist than it sounds.
Stop foliar spraying after the second week of bloom. Anything that lands on a developing trichome is still there at harvest and is tasted rather than seen. In the last three weeks the night temperature decides which terpenes lead: held at 16-18°C the caryophyllene comes forward, while a warmer finish protects the lighter bisabolol notes.
Then the cure, which is where Irish growers lose most of what they built. A ten to fourteen day hang wants 17°C and something near 58% humidity, and the ambient air here will not supply either for most of the year — a closed room and a small dehumidifier will. Into glass afterwards, burped twice daily for a fortnight. The myrcene layer arrives somewhere in weeks three and four, not before.
Flowering: Approximately 7–9 Weeks. Indoor yield: 300 gr/m². Outdoor yield: 300 grams. Plant height: 90-120 cm. Medium. Rated medium difficulty.
Flavour, aroma and effect
XXX 420 arrives in order. The first draw at 18% THC gives peppercorn heat that lands at the back of the throat. The relaxed, sleepy, happy character follows in minutes, as weight behind the eyes that works down through the shoulders. By a quarter of an hour it reads as physical stillness rather than sedation — a strong disinclination to stand up. Two to three hours at a sensible dose. Myrcene underneath contributes depth beneath the rest.
Terpene breakdown
Primary: Caryophyllene · Secondary: Myrcene · Tertiary: Bisabolol. Temperature decides how much of this profile survives. Low vaporisation at 180-188°C keeps myrcene and bisabolol audible over the caryophyllene; run it hotter, or burn it, and all three collapse into one note that is pleasant enough and tells you nothing.
Who it suits
Who does well with XXX 420? Back-garden and balcony growers in Dublin, Cork and Galway. Anyone who wants a crop dry and put away before the autumn closes in. Indoor growers short of headroom. The autoflowering genetics run to their own clock, so there is no schedule to manage and no anxiety about light leaks. Rated medium, which means a moderate learning curve that rewards attention without needing specialist kit.
Effects
Best For
Strain Type
Strain Data Sheet
Packaging
Regular
Seeds
authenticity
lining
number
Related Strains

XXX 420 Feminised
XXX 420 Feminised cannabis seeds for Irish growers. Indica strain · 18% THC · relaxed, sleepy, happy. Discreet packaging, nationwide delivery, sourced grow figures.

A-Train Auto
A-Train Auto — premium indica cannabis seeds suited to Irish growing conditions. 21% THC with relaxed, sleepy, happy effects. Discreet delivery across Ireland, with sourced grow figures on every strain page.

Ace of Spades Auto
Order Ace of Spades Auto seeds online in Ireland. A quality indica cultivar at 20% THC delivering relaxed, sleepy, happy. Chosen for a short season and a damp finish. Fast shipping and a germination guarantee.

Afghan Kush Auto
Grow Afghan Kush Auto in Ireland. Indica genetics testing at 20% THC. Known for relaxed, sleepy, happy effects. Ships discreetly nationwide with sourced grow figures.
XXX 420 Auto — Breeder Information
Royal King GeneticsBred 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.
XXX 420 is our F5 autoflower line. Five rounds of selection have fixed both the autoflower trigger and the purple expression the cultivar is known for. The recessive ruderalis trait demands this depth of work to express uniformly.
Lock the autoflower trait in XXX 420 through five generations of selection.
Chosen for trichome coverage, stout structure and consistent flowering time across the pack.
Royal King Genetics elite-cut archive — pollen from a maintained S1 line of the original elite mother.