G13
Breeder: Neville Schoenmakers / The Seed Bank
A legendary indica originating from a single clone allegedly liberated from a U.S. government research facility at the University of Mississippi in the late 1970s. Neville Schoenmakers introduced it to commercial breeding through The Seed Bank in Amsterdam, where it became one of the most mythologized genetics in cannabis history. The original mother was never seeded — all modern G13 derivatives are crosses made from that single female cutting.
Lineage & Genetics
Cross: Afghani Landrace (clone-only)
G13 descends from a pure Afghani landrace — a broad-leaf indica adapted to the harsh mountain climates of Afghanistan. Afghani landraces are prized for extreme resin production, compact structure, and heavy sedating effects. The G13 clone is believed to represent an elite selection from government research stock at the University of Mississippi, where cannabis varieties were cultivated for federal research programs. No second parent exists — G13 is a clone-only pure indica that was never crossed until breeders like Neville Schoenmakers and later Dr. Greenthumb produced hybrids and S1 reversals from the original cutting.
Terpene Profile
Myrcene — Dominant terpene providing earthy, herbal aroma and heavy sedating body effects characteristic of pure Afghani genetics
Caryophyllene — Peppery spice that adds warmth and contributes anti-inflammatory properties via CB2 receptor activation
Pinene — Pine and woody notes that contribute to the strain's forest-floor earthiness
Limonene — Subtle citrus brightness that lifts the otherwise heavy, earthy profile
Linalool — Floral lavender undertone that reinforces the sedative, calming effects
Aroma: Earthy, pine, pungent skunk, woody undertones.
Flavor: Sweet earth and pine with berry and skunk on the exhale.
Effects & Experience
Onset: Moderate — an initial euphoric head buzz arrives within minutes before the heavy body effects take hold.
Euphoric onset followed by heavy full-body sedation and couch-lock. The initial cerebral uplift fades quickly into profound physical sedation lasting 2–4 hours. Not recommended for daytime productivity or novice users due to intensity.
Duration: 2–4 hours
Commonly Reported Uses
Grower's Notes
G13 is one of the most storied genetics in cannabis — a pure Afghani clone that never existed as a commercial seed line until breeders like Dr. Greenthumb produced S1 reversals. It grows short and bushy with dense internodal spacing, produces extremely resinous flowers, and delivers one of the heaviest body stones available. Ideal for evening or nighttime use and patients seeking deep physical relief.
Flowering & Harvest
Flowers in 8–10 weeks under a strict 12/12 photoperiod. Trichomes should be checked daily starting week 7 — harvest when heads shift from milky-white to 20–30% amber for maximum sedative effect. Outdoor crops finish late September through October in temperate climates.
Environment
Maintain 70–80°F (21–27°C) during lights-on and drop no more than 10°F at night. Relative humidity should stay at 45–55% in veg and drop to 35–45% during flower to prevent mold in the dense bud structure. G13 is frost-tolerant outdoors in spring and fall but performs best in controlled indoor rooms.
Training & Canopy
Naturally stays short (under 100 cm indoors) with minimal stretch. Responds extremely well to SOG at 1-gallon pots with 16–25 plants per m² — the original Dr. Greenthumb recommendation. LST and SCROG also work well to expose lower bud sites. Topping is optional given its naturally compact structure.
Nutrients & Feeding
Heavy feeder during mid-flower. Increase phosphorus and potassium starting week 3 of bloom. Under LED lighting, supplement cal-mag at 2–3 mL/gal from week 2 of veg onward to prevent the most common deficiency. Flush for 10–14 days before harvest for clean flavor.
Pest & Disease
Dense bud structure makes it susceptible to botrytis (bud rot) in high-humidity environments. Ensure strong airflow through the canopy with oscillating fans positioned to move air through the leaves, not just over the top. Defoliate lower fan leaves in early flower to improve circulation. Inspect inner colas closely in late flower.
Yield Optimization
Indoor yields of 450–550 g/m² are achievable under quality LED at 800–1000 µmol/m²/s PPFD during flowering. Outdoor plants in full sun with 5–7 gallon containers can produce 500–700 g/plant. High phosphorus during weeks 4–6 of flower maximizes bud density.
Drying & Curing
Whole-plant hang dry at 60°F / 60% RH for 10–14 days until small stems snap cleanly. Jar cure for minimum 3–4 weeks — the earthy-pine terpene profile deepens significantly with extended curing. Boveda 62% packs help maintain optimal moisture during cure.
Breeding Notes
The original G13 clone was never pollinated in its pure form until modern S1 techniques. Neville crossed it with Hash Plant, Northern Lights #2, Haze, and Skunk #1 to create legendary hybrids. Shantibaba (Mr. Nice Seeds) and Soma continued the lineage. Any 'pure G13 seed' is either an S1 reversal or a very tight backcross — true clone-only genetics.
Best Use Case
Nighttime strain for experienced consumers. The initial euphoric uplift fades quickly into profound physical sedation lasting 2–4 hours. Medical patients report strong efficacy for chronic pain, insomnia, and muscle spasms. Not recommended for daytime productivity or novice users due to intensity.
History & Origin
G13 is one of the most legendary strains in cannabis history. According to the most widely circulated account, a single clone was allegedly smuggled out of a U.S. government research facility at the University of Mississippi in the late 1970s, where the federal government was cultivating cannabis varieties for research. The clone made its way to Neville Schoenmakers, who introduced it to commercial breeding through The Seed Bank in Amsterdam during the 1980s. The original mother was never seeded — all modern G13 derivatives are crosses made from that single female cutting. Neville crossed G13 with Hash Plant, Northern Lights #2, Haze, and Skunk #1 to create legendary hybrids. Shantibaba (Mr. Nice Seeds) and Soma continued the lineage. Dr. Greenthumb later produced S1 reversals, making seed stock available for the first time. The strain's mythological status, combined with its genuinely exceptional resin production and potent effects, has made it one of the most referenced genetics in cannabis culture.
Notable Crosses
Strains bred using G13 as a parent:
Frequently Asked Questions
6 common questions about G13
What is G13 and what are its genetics?
G13 is a indica cannabis strain (100% Indica) bred by Neville Schoenmakers / The Seed Bank. It is a cross of Afghani Landrace (clone-only), testing at 20–28% THC. A legendary indica originating from a single clone allegedly liberated from a U.S. government research facility at the University of Mississippi in the late 1970s.
What does G13 smell and taste like?
G13's dominant terpenes are Myrcene, Caryophyllene. The aroma is described as earthy, pine, pungent skunk, woody undertones.. The flavor profile features sweet earth and pine with berry and skunk on the exhale..
What are the effects of G13?
Moderate — an initial euphoric head buzz arrives within minutes before the heavy body effects take hold. Euphoric onset followed by heavy full-body sedation and couch-lock. The initial cerebral uplift fades quickly into profound physical sedation lasting 2–4 hours. Duration is typically 2–4 hours. Commonly reported uses include Chronic pain, Insomnia, Stress, Anxiety.
How hard is G13 to grow?
G13 is rated intermediate difficulty. It flowers in 8–10 weeks, reaches 45–100 cm indoor, 120–180 cm outdoor in height, and yields 450–550 g/m² indoors. Best suited for indoor preferred; warm dry climate outdoors environments.
What are the parent strains of G13?
G13 is a cross of Afghani. G13 descends from a pure Afghani landrace — a broad-leaf indica adapted to the harsh mountain climates of Afghanistan. Afghani landraces are prized for extreme resin production, compact structure, and heavy sedating effects.
What strains were bred from G13?
G13 has been used as a parent in several notable crosses, including G13 x Hash Plant, G13 x Haze, G13 x Northern Lights #2, G13 x Skunk #1. Its genetics contribute to a wide range of modern cultivars.
Want to Grow G13?
Check our genetics menu for available clones or call us to discuss your growing needs.