IndicaIndica-dominant (~90/10)28-32% THC

GDP x Purest Indica

Also known as: Granddaddy Purple x Purest Indica, Grandaddy Purple x Purest Indica

Breeder: Authentic Genetics (Todd McCormick); grown/selected in-house by Prime Cuts Nursery

GDP x Purest Indica is a fast-finishing, deeply sedative indica bred by Authentic Genetics (Todd McCormick) and grown out and pheno-selected in-house by Prime Cuts Nursery. It marries the world-famous Granddaddy Purple mother — sweet grape terpenes, deep purple color, heavy resin — with the Purest Indica (Steve Murphy Afghan) father, which adds body, density, faster finish, and an earthy, acrid old-school Afghan funk. The result is a compact, resin-heavy, vibrantly purple plant with a terpene arc that spans sweet berry to gassy Afghan and a stated 28-32% THC on the PCN cut.

Lineage

Granddaddy Purple x Purest Indica

THC Range

28-32%

Flower Time

8-9 weeks

Difficulty

Intermediate

Lineage & Genetics

Cross: Granddaddy Purple x Purest Indica

Parent strains in encyclopedia:Granddaddy Purple→Purest Indica→

Mother — Granddaddy Purple (Ken Estes, 2003, SF Bay Area): contributes the grape/berry terpene profile, dramatic deep-purple anthocyanin expression, dense oversized resin-frosted colas, strong bag appeal, heavy full-body sedation, large yields, and an ~8-9 week finish. GDP is one of the archetypal myrcene-dominant strains, driving its sedative "purple effect." Father — Purest Indica, the "Steve Murphy Afghan" (Authentic Genetics IBL): a pure Afghan/Hindu Kush landrace inbred line that contributes broadleaf/hash-plant structure (short, dense, Christmas-tree), a faster finish, heavier resin/hash-plant character, an acrid earthy "old-school funk" (burnt rubber, skunk, thiols), a sedative pure-Afghan body effect, and a preference for low humidity. As a male it breeds consistently, contributing body, density, and finish time without overpowering the mother. The breeder-stated combined expectation is compact growth, vibrant/deep-purple coloration, dense trichomes, a fast finish, and a terpene arc spanning sweet berry to gassy Afghan.

Lineage Dispute

Two roles must be kept distinct: Authentic Genetics (Todd McCormick's AG Seed Co) is the breeder of the released regular-seed cross — the true Granddaddy Purple clone as mother, the Purest Indica (Steve Murphy Afghan) male as father — while Prime Cuts Nursery is growing the regular seeds and selecting a keeper phenotype in-house; PCN is the pheno-hunter/producer, not the originator of the cross. Separately, the Granddaddy Purple parent itself carries a documented lineage dispute: Leafly and Strainpedia record it as Mendo Purps x Skunk x Afghanistan, while most seed banks and MedicalJane list Purple Urkle x Big Bud. These accounts are widely treated as complementary rather than contradictory (Purple Urkle is believed to be a Mendocino Purps phenotype and Big Bud carries Afghani ancestry), and either way the takeaway is a heavy Afghani indica base with a strong purple/berry line. Because these are segregating regular seeds, not every phenotype will express as deeply as the selected keeper.

Terpene Profile

DOMINANT

Myrcene — Best inference for the cross (no finished-flower COA published). GDP is strongly myrcene-dominant (~0.58% in one profile; 0.73% w/w on a GDP vape COA); earthy/musky/grape and drives sedation and muscle relaxation as a THC amplifier.

SECONDARY

Caryophyllene — Spicy/peppery/clove gas note; a CB2 agonist and anti-inflammatory (~0.32% in a GDP profile, 0.47% w/w on the GDP vape COA).

SECONDARY

Linalool — Floral/lavender, anxiolytic/sedative (~0.18% in a GDP profile; notably high at 1.96% w/w on a GDP vape extract COA — extract values, not raw flower).

SECONDARY

Humulene — Minor/trace supporting terpene from the GDP side.

Aroma: A spectrum from sweet berry to gassy Afghan: Granddaddy Purple's sweet, fruity grape/berry up front, wrapped in Purest Indica's earthy, acrid funk — burnt rubber, skunk, and acrid earth. Nose intensity is expected to be loud given both parents' pungency.

Flavor: A grape/berry sweetness on the nose that turns gassier, earthier, and more skunk-forward as the buds are broken or ground; on the exhale a fruity-then-funky finish with a hashy, earthy linger. This is the breeder-stated "sweet berry to gassy Afghan" arc, with the finished-cut detail inferred from parent behavior.

Effects & Experience

Onset: Begins with dreamy cerebral euphoria that quickly gives way to dominant, heavy full-body relaxation (from the GDP side); onset detail is inferred from the parents.

A perfectly sedative, deeply relaxing indica experience that tends toward couch-lock and getting "fixed in one spot," reinforced by the Purest Indica father's heavy, narcotic Afghan body stone. GDP-class strains are repeatedly rated very-high sedation and often feel stronger than their THC number suggests, attributed to myrcene-linalool synergy.

Duration: Long for an indica; a multi-hour wind-down is typical of GDP-class strains (inferred from parent reporting).

Commonly Reported Uses

Insomnia / sleepChronic painMuscle spasmsStress / anxietyAppetite loss / nausea

Grower's Notes

Flower

8-9 weeks

Indoor Yield

~450-600 g/m²

Outdoor Yield

~400-600 g/plant

Difficulty

Intermediate

Height / Stretch

Short/compact indica, ~60-90 cm indoors;

Environment

Dry climate, low humidity (40-50% RH flower),

GDP x Purest Indica is an in-house Prime Cuts breeding project rather than a commercial seed line, so field data on the exact cross is limited, but its parentage tells you how to run it. It is a compact, resin-drenched pure indica that stacks Granddaddy Purple's sweet grape-berry terpenes over Purest Indica's earthy Afghan hash funk, and it demands humidity and airflow discipline in late flower to protect its dense colas. The guidance below leans on the documented behavior of both parents, since the finished PCN cut has little third-party data.

Growth Structure and Training

Expect a short, stocky, broad-leaf indica bush with thick stalks and tight internodal spacing. The Afghan side keeps her squat and the GDP side keeps her manageable, roughly 60 to 90 centimeters indoors and taller outdoors. Low-stress training and a SCROG net pay off because the structure is dense and inward-facing, but heavy defoliation is risky given how much this plant wants to close up on itself.

Flowering Time and Harvest

Both parents finish reasonably quickly, so plan on a roughly eight to nine week indoor window, and the Afghan father should pull the finish toward the fast end. Watch trichomes rather than the calendar and pull at mostly cloudy with roughly ten to twenty percent amber for the sedative, narcotic finish this cross is built for. Outdoors, expect an early-to-mid October chop.

Yield

Yield is moderate to good. Granddaddy Purple delivers about 450 to 600 grams per square meter indoors and 400 to 600 grams per plant outdoors, and Afghan hash lines run similar figures. Budget for solid rather than record yields, with dense, heavy colas that may need support in late flower.

Nutrient Management

Feed it like a heavy indica. Front-load calcium, magnesium, and nitrogen in early veg, then transition to a phosphorus and potassium forward bloom. Add phosphorus and potassium at weeks five through seven for bud density, but do not overfeed phosphorus, which invites lockout, and taper nitrogen late for a clean fade.

Environment and Climate

This is a dry-climate plant. Keep flowering relative humidity at 40 to 50 percent and never let it climb during dark periods, because the dense colas trap moisture and botrytis is the number-one threat. Run canopy temperatures of 24 to 26 degrees Celsius by day, and for purple drop night temperatures to 10 to 15 degrees Celsius for the final two to three weeks, though phenotypes leaning Afghan may stay greener.

Lighting

Full-spectrum LED or HPS both finish this cross well; keep the canopy under even, strong intensity.

Pest and Disease Resistance

The Afghan landrace heritage brings real hardiness and pest resistance, but the dense buds mean mold and mites hiding in the canopy are the practical risks. Scout weekly and keep IPM tight, and remember that purple buds can mask early gray mold, so inspect closely.

Bud Structure and Trichomes

Expect chunky, rock-hard indica nugs caked in capitate-stalked trichomes. The flowers are myrcene- and caryophyllene-forward, carrying grape and berry candy over earthy Afghan incense and hash funk.

Color Development

Deep purple-to-violet tones develop when the plant is finished cold, driven by the Granddaddy Purple anthocyanin genetics. Because these are segregating regular seeds, phenotypes leaning Afghan may hold green.

Drying and Curing

Slow-dry over 10 to 14 days at 15 to 18 degrees Celsius and 50 to 55 percent relative humidity in the dark to lock in the purple, since anthocyanins brown from heat rather than time. Cure in glass at 58 to 62 percent relative humidity, burping daily through the first week.

Wash and Extraction

This is a hash-maker's plant. The Afghan resin density and large trichome heads make it a natural for ice-water extraction and dry sift. Fresh-freeze at peak ripeness and wash cold at 0 to 4 degrees Celsius, letting the 73 to 120 micron fraction carry the full-melt. Afghan hash lines commonly return three to six percent ice-water yield.

History & Origin

This cross sits at the intersection of two documented histories. Granddaddy Purple emerged in 2003 from the San Francisco Bay Area medical scene via Ken Estes, becoming a defining strain of California's "purple era" prized for visual appeal, reliable sedation, and big yields. Purest Indica is a living piece of cannabis history — the 1979 "Steve Murphy Afghan" that seeded the entire Northern Lights family, preserved in a freezer since the early 1980s and reproduced by Todd McCormick's Authentic Genetics after Seattle Greg supplied the original stock in 2020. The cross itself is a recent Authentic Genetics breeding project; McCormick's stated goal was to go "back to the source" and re-marry GDP to a pure Afghan (echoing his Granddaddy Purple x NL#5 work). Prime Cuts Nursery is carrying that regular-seed line forward as an in-house grow-out and selection, framing it as a highly sought-after breeding project.

Frequently Asked Questions

6 common questions about GDP x Purest Indica

What is GDP x Purest Indica and what are its genetics?

GDP x Purest Indica is a indica cannabis strain (Indica-dominant (~90/10)) bred by Authentic Genetics (Todd McCormick); grown/selected in-house by Prime Cuts Nursery. It is a cross of Granddaddy Purple x Purest Indica, testing at 28-32% THC. GDP x Purest Indica is a fast-finishing, deeply sedative indica bred by Authentic Genetics (Todd McCormick) and grown out and pheno-selected in-house by Prime Cuts Nursery. It marries the world-famous Granddaddy Purple mother — sweet grape terpenes, deep purple color, heavy resin — with the Purest Indica (Steve Murphy Afghan) father, which adds body, density, faster finish, and an earthy, acrid old-school Afghan funk.

What does GDP x Purest Indica smell and taste like?

GDP x Purest Indica's dominant terpenes are Myrcene. The aroma is described as a spectrum from sweet berry to gassy afghan: granddaddy purple's sweet, fruity grape/berry up front, wrapped in purest indica's earthy, acrid funk — burnt rubber, skunk, and acrid earth. nose intensity is expected to be loud given both parents' pungency.. The flavor profile features a grape/berry sweetness on the nose that turns gassier, earthier, and more skunk-forward as the buds are broken or ground; on the exhale a fruity-then-funky finish with a hashy, earthy linger. this is the breeder-stated "sweet berry to gassy afghan" arc, with the finished-cut detail inferred from parent behavior..

What are the effects of GDP x Purest Indica?

Begins with dreamy cerebral euphoria that quickly gives way to dominant, heavy full-body relaxation (from the GDP side); onset detail is inferred from the parents. A perfectly sedative, deeply relaxing indica experience that tends toward couch-lock and getting "fixed in one spot," reinforced by the Purest Indica father's heavy, narcotic Afghan body stone. GDP-class strains are repeatedly rated very-high sedation and often feel stronger than their THC number suggests, attributed to myrcene-linalool synergy.. Duration is typically long for an indica; a multi-hour wind-down is typical of gdp-class strains (inferred from parent reporting).. Commonly reported uses include Insomnia / sleep, Chronic pain, Muscle spasms, Stress / anxiety.

How hard is GDP x Purest Indica to grow?

GDP x Purest Indica is rated intermediate difficulty. It flowers in 8-9 weeks, reaches short/compact indica, ~60-90 cm indoors; taller outdoors in height, and yields ~450-600 g/m² indoors. Best suited for dry climate, low humidity (40-50% rh flower), strong airflow; cool nights final 2-3 weeks for purple environments.

What are the parent strains of GDP x Purest Indica?

GDP x Purest Indica is a cross of Granddaddy Purple and Purest Indica. Mother — Granddaddy Purple (Ken Estes, 2003, SF Bay Area): contributes the grape/berry terpene profile, dramatic deep-purple anthocyanin expression, dense oversized resin-frosted colas, strong bag appeal, heavy full-body sedation, large yields, and an ~8-9 week finish. GDP is one of the archetypal myrcene-dominant strains, driving its sedative "purple effect." Father — Purest Indica, the "Steve Murphy Afghan" (Authentic Genetics IBL): a pure Afghan/Hindu Kush landrace inbred line that contributes broadleaf/hash-plant structure (short, dense, Christmas-tree), a faster finish, heavier resin/hash-plant character, an acrid earthy "old-school funk" (burnt rubber, skunk, thiols), a sedative pure-Afghan body effect, and a preference for low humidity.

Does GDP x Purest Indica turn purple?

Yes. GDP x Purest Indica is known to express purple coloration, with reported colors including purple, green. Cooler nighttime temperatures during late flowering typically intensify anthocyanin expression.

Sources & References (46)

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