Written by Ad OpsHistory
M 39 Granddaddy is a modern Canadian hybrid bred by Quebec Cannabis Seeds (QCS), a breeder known for adapting classic genetics to northern latitudes. The strain’s name hints at its parentage, blending the Canadian workhorse M39 with the California-born Granddaddy Purple. QCS positioned M 39 Granddaddy as a balanced indica/sativa, aiming to capture the resilience and yield of M39 with the resin-soaked flavor and body effects of Granddaddy Purple. The result is a cultivar designed for both commercial-scale reliability and boutique-grade character.
The M39 ancestor is a legend across Canada’s legacy market of the 1990s and early 2000s, often associated with dependable harvests and fast finishes. Historically, M39 is linked to Northern Lights #5 and Skunk #1 stock, lines known for vigor and uniformity. Growers valued M39 because it delivered under varied conditions, even in less forgiving environments. That reliability made it a staple in warehouse grows from Quebec to British Columbia.
Granddaddy Purple (GDP), by contrast, rose to prominence in California for its striking purple hues and grape-berry terpene profile. GDP is widely described as delivering simultaneous cerebral euphoria and physical relaxation, a duality referenced by industry leaders like Leafly. The strain’s parentage is commonly reported as Purple Urkle x Big Bud, combining color and flavor with heavy, resinous flowers. Those attributes make GDP a prized component in modern crosses.
By pairing M39’s productivity with GDP’s flavor and bag appeal, QCS created a hybrid intended to satisfy both traditional and contemporary tastes. The breeding objective was to keep flowering fast and structure sturdy, while elevating terpene intensity and resin density. Early grower reports place M 39 Granddaddy’s flowering window around 8–9 weeks indoors, aligning with both parents’ timelines. The cultivar also shows a finishing window outdoors around late September to early October in temperate zones, a crucial advantage for Canadian gardeners.
Genetic Lineage
M 39 Granddaddy’s genetic lineage blends two historically important lines: the balanced, production-focused M39 and the terpene-rich Granddaddy Purple. M39 is widely believed to trace back to Northern Lights #5 x Skunk #1, which contributed short flowering times and uniform, skunk-forward vigor. GDP, typically documented as Purple Urkle x Big Bud, adds purple coloration, dense calyxes, and a signature sweet grape-and-berry bouquet. In combination, these genetics suggest a 50/50 hybrid or near-balanced offspring, consistent with reports describing M39 as a 50/50 hybrid.
From M39, breeders expect strong apical dominance, rapid vegetative growth, and dependable internodal spacing. The NL5/Skunk background is known for stability and for handling higher nutrient loads without dramatic stress. M39 also became synonymous with production in the Canadian market, where short summers rewarded its quick turnaround. Those traits are often preserved in crosses, allowing predictable performance across environments.
GDP contributes distinct anthocyanin expression, which can drive purple tones when night temperatures dip below 18–20°C. It also carries a terpene profile dominated by myrcene, caryophyllene, and pinene that reads as sweet grape, dark berry, and earthy spice. GDP’s Big Bud parentage adds thick colas and copious resin, traits that benefit both flower quality and extraction yields. These features make GDP a frequent choice for breeders aiming to elevate aroma and bag appeal without losing potency.
The combined pedigree of M 39 Granddaddy suggests a plant that is cooperative in the garden yet nuanced in the jar. Flowering typically completes in 56–63 days in controlled indoor environments, with phenotypes leaning GDP occasionally stretching to 65 days. Outdoor crops in higher latitudes can finish before heavy autumn rains, a practical advantage. The result is a hybrid that pairs legacy practicality with contemporary flavor and aesthetics.
Appearance
In flower, M 39 Granddaddy forms dense, medium-sized colas that can stack tightly along upper branches. Buds are typically lime to forest green, with GDP-leaning phenotypes displaying violet to eggplant hues after cool nights. Pistils mature from tangerine to rusty orange, offering vibrant contrast against the calyxes. A heavy blanket of trichomes makes the buds appear frosted, particularly near peak ripeness.
Leaf morphology reflects a balanced indica/sativa heritage, with broad leaflets early that can thin slightly as plants mature. Internodal spacing is moderate, allowing light to penetrate while still supporting compact cola formation. Plants generally reach 80–140 cm indoors without aggressive training, and 180–250 cm outdoors with longer veg times. Stems are sturdy enough to bear weight, though late flower often benefits from trellising.
Trimmed flowers tend to be slightly conical with tight calyx-to-leaf ratios, easing post-harvest labor. Trichome heads mature from clear to cloudy and then amber, providing a visible cue for harvest timing. Properly cured buds exhibit a subtle sheen due to abundant resin. Bag appeal is strong, with color contrast and crystal coverage standing out in bright light.
Aroma
Aromatically, M 39 Granddaddy blends grape and sweet berry from the GDP side with a clean, floral-skunk character from M39. Many consumers describe top notes of grape candy and berry jam, interlaced with earthy spice and faint pine. On the surface, it presents as dessert-like and inviting, with deeper layers that hint at classic skunk ancestry. The bouquet intensifies significantly in the final two weeks of flower as trichomes swell.
There is spirited debate about M39’s contribution to aroma in modern crosses. Some legacy growers have argued M39 “doesn’t stink at all” in flower and is a balanced 50/50 hybrid, emphasizing a clean, pleasant nose rather than the heavy musk some expect. In M 39 Granddaddy, this can translate to a more refined, less acrid skunk tone beneath the grape-forward top end. The result is a nose that is bold but not overwhelming, especially after a slow cure.
Curing technique greatly influences the final aromatic profile. A 10–14 day dry at 18–21°C and 55–62% RH, followed by 4–8 weeks of jar curing, tends to preserve volatile terpenes. Burping jars daily in week one, then every 2–3 days thereafter, helps moderate humidity and avoid ammoniac off-notes. Properly cured samples reveal layered complexity that holds up well in vaporizers and glass.
Flavor
On the palate, M 39 Granddaddy’s first impression is grape soda and mixed berries, a clear nod to Granddaddy Purple. The mid-palate delivers earthy spice and a gentle skunk-herbal bridge from the M39 side. Subtle pine and citrus-zest edges can appear on the exhale, likely driven by pinene and limonene fractions. The aftertaste lingers as sweet berry compote with a dusty cocoa earthiness.
Flavor intensity correlates with cure quality and harvest timing. Early harvests can skew brighter and more herbal, while late harvests amplify sweet berry and deeper earth. Vaporization at 175–190°C tends to accentuate fruit esters and floral nuance. Combustion presents a fuller body and more pronounced spice, with the skunk note rising at higher temperatures.
In extracts, the flavor often concentrates into grape candy, violet-lilac florals, and resinous pine. Live rosin from well-grown material can showcase pronounced concord-grape tones with creamy sweetness. Hydrocarbon extracts may pull more of the skunk-pine backbone, adding structure to the fruit. Across formats, the blend remains approachable and distinct.
Cannabinoid Profile
M 39 Granddaddy is typically a THC-dominant hybrid, with lab results from similar parentage suggesting a range of 18–24% THC by dry weight. CBD is usually low, often below 0.5–1.0%, with occasional phenotypes approaching 1% under specific conditions. Minor cannabinoids such as CBG can register in the 0.2–1.0% range, which may contribute to perceived smoothness and focus. THCV tends to be trace, most often below 0.2% in sample sets from related lines.
Total terpene content commonly falls between 1.5–3.0%, which supports robust aroma and flavor perception. Consumers often report that samples over 2.0% total terpenes feel more potent at equal THC levels, a synergy consistent with current entourage-effect hypotheses. Inhalation onset is generally within 3–10 minutes, with peak effects at 30–45 minutes and total duration of 2–3 hours. Oral formats shift onset to 30–120 minutes with longer plateaus.
Extraction yields are solid due to GDP’s resin output and M39’s dense floral structure. Solventless rosin yields from high-grade flower commonly land in the 18–22% range, with standout runs surpassing 22% under optimized conditions. Hydrocarbon extraction can chart higher returns, often 20–25%+ depending on biomass and process. Such efficiency makes the cultivar attractive for producers balancing quality and throughput.
Potency consistency improves with uniform phenoselection and stable environmental controls. Growers targeting medical markets often harvest at a slightly earlier window to keep THC high and sedative terpenes moderate. Recreational markets may push maturity to maximize richness and couchlock character, trading a minor THC decrease for fuller terpene expression. Clear, cloudy, and amber trichome ratios provide a practical harvest gauge to tune outcomes.
Terpene Profile
The dominant terpenes in M 39 Granddaddy are typically myrcene, beta-caryophyllene, and alpha-pinene, reflecting the GDP and M39 influences. Myrcene often leads at 0.5–1.2% of dry weight, imparting ripe berry, mango, and earthy sweetness with a relaxing undertone. Beta-caryophyllene frequently appears at 0.3–0.8%, adding peppery spice and engaging CB2 receptors for potential anti-inflammatory effects. Alpha-pinene commonly lands at 0.15–0.5%, lending pine brightness and potential attentional support.
Secondary terpenes can include humulene, limonene, and linalool in measurable amounts. Humulene at 0.1–0.4% contributes woody, herbaceous dryness that reins in sweetness and may complement caryophyllene. Limonene at 0.1–0.4% brings citrus lift and can boost perceived mood and clarity. Linalool at 0.05–0.25% adds floral lavender notes and may contribute to relaxation.
Aromatics vary with phenotype, nutrient regime, and post-harvest handling. Cooler night temperatures in late flower can enhance anthocyanin expression and slightly shift the aromatic balance toward darker fruit. Slow drying preserves monoterpenes like myrcene and pinene that are more volatile. Aggressive drying can dull the top notes and leave a flatter, earthier profile.
Compared with its GDP parent, M 39 Granddaddy often presents a cleaner, less syrupy nose due to M39’s influence. Compared with straight M39, it is sweeter and more fruit-forward, with enhanced resin density. The net effect is a dessert-like bouquet with old-school structure and depth. That duality gives the cultivar broad appeal among both legacy and new consumers.
Experiential Effects
M 39 Granddaddy delivers a blended effect profile that mirrors its balanced genetics. The onset often brings a buoyant cerebral lift, promoting positive mood and casual sociability. As the session progresses, a warm, body-centered relaxation spreads through shoulders and limbs. The combination echoes descriptions of Granddaddy Purple’s signature fusion of mind and body effects.
At moderate doses, users report clear-headed contentment and a gentle easing of tension. Many describe this as functional relaxation suitable for music, light conversation, and creative hobbies. The pinene fraction can preserve a degree of focus, especially early in the experience. As effects deepen, caryophyllene and myrcene can tilt the body feel toward a cozy heaviness.
Higher doses may introduce heavier sedation, couchlock, and increased appetite. Temporal perception can slow, and the motivation to engage in demanding tasks may drop. Dry mouth and dry eyes are the most commonly reported side effects, with occasional dizziness in sensitive individuals. Staying hydrated and pacing intake mitigates most unwanted outcomes.
Duration varies by route of administration and individual tolerance. Inhalation effects typically last 2–3 hours with a tapering tail. Edibles or encapsulated preparations can extend relief to 4–6 hours or more but require careful dosing. New users should start low and go slow to find their comfort zone.
Potential Medical Uses
While formal clinical data on M 39 Granddaddy specifically are limited, its chemistry aligns with several common therapeutic targets. THC-dominant, myrcene- and caryophyllene-rich cultivars are frequently chosen for chronic pain, muscle tension, and stress-related sleep disturbances. The National Academies of Sciences, Engineering, and Medicine concluded there is substantial evidence supporting cannabis for chronic pain in adults. Observational surveys also report improvements in sleep quality and reduced anxiety for many patients, though individual responses vary.
For pain, beta-caryophyllene’s interaction with CB2 receptors may complement THC’s analgesic potential. Myrcene and linalool can add a calming component that eases perceived pain intensity and aids rest. Many patients using similar profiles report 20–50% reductions in daily pain scores, though outcomes depend on dose and product format. Vaporized flower allows rapid titration, while tinctures provide longer coverage.
For insomnia, sedative-leaning phenotypes and later harvest windows can be advantageous. Products showing myrcene above 0.5% and THC above 18% are commonly selected for nighttime routines. Patients often report faster sleep onset and fewer overnight awakenings. However, sensitive users may experience next-day grogginess at higher doses.
For anxiety and mood, low to moderate doses may promote relaxation without overt intoxication. The pinene and limonene components can help offset THC-induced short-term memory fog and contribute to a lighter, more uplifted affect. Individuals with anxiety disorders should approach high-THC products cautiously, as overconsumption can provoke unease. Balanced dosing and controlled set-and-setting are key.
Nausea and appetite loss are additional targets where THC-forward cultivars show utility. Many patients note increased appetite within 30–60 minutes after inhalation. Slow, steady dosing maintains symptom control without overwhelming sedation. As always, medical decisions should be made in consultation with a qualified healthcare professional, especially when combining cannabis with other medications.
Cultivation Guide
Environment and vigor. M 39 Granddaddy grows with the pragmatic confidence of its M39 heritage and the resin-driven intent of GDP. Indoors, aim for 24–28°C day and 19–22°C night during veg, shifting to 22–26°C day and 17–20°C night in flower. Relative humidity targets of 60–70% in veg and 45–55% in flower help balance growth and pathogen risk. A balanced VPD of 0.8–1.1 kPa in veg and 1.1–1.4 kPa in flower supports steady transpiration.
Plant size and training. Expect 80–140 cm indoors with moderate stretch of 1.2–1.8x after flip. The structure responds well to topping at the 4th–6th node, low-stress training, and SCROG to even the canopy. Trellising prevents late-flower leaning as colas thicken, especially in GDP-leaning phenotypes. Supercropping early in flower can reduce apical dominance and improve light distribution.
Mediums and feeding. The cultivar performs well in soil, coco, or recirculating hydro, reflecting the hardiness often seen in M39 lines. In coco, maintain pH 5.7–6.2; in soil, aim for pH 6.2–6.8. Target EC 1.2–1.6 in late veg and 1.6–2.1 through mid flower, stepping down in the final two weeks. Maintain calcium and magnesium availability, especially under high-intensity LEDs.
Lighting and DLI. Provide 400–600 µmol/m²/s PPFD in veg and 700–900 µmol/m²/s in flower for most phenotypes. Advanced growers can push 900–1050 µmol/m²/s with supplemental CO2 at 900–1200 ppm, provided temperature and nutrition are tuned. Daily Light Integral targets of 35–45 mol/m²/day in flower typically drive optimal yields. Keep canopy distance appropriate to avoid light stress that can mute terpenes.
Watering strategy. Allow 10–15% runoff in coco and hydro to prevent salt buildup. In soil, water to full saturation and let the medium approach, but not reach, dry-back before the next irrigation. Automated drip systems stabilize inputs and reduce human error. Oxygenated root zones translate into thicker stems and larger, denser flowers.
Vegetative timeline. A 3–5 week veg is adequate for most indoor grows to fill a 1–1.2 m² space with 4–6 plants. Use silica supplementation to reinforce cell walls and improve stress tolerance. Keep nodes tight with adequate blue spectrum during veg. Prune lower growth prior to flip to concentrate energy on top sites.
Flowering schedule. M 39 Granddaddy generally completes in 8–9 weeks indoors, with some GDP-leaning phenotypes running to week 9.5. Outdoors in temperate climates, plan to harvest late September to early October, which suits Canadian and northern U.S. seasons. As flowers bulk up, increase airflow with oscillating fans to deter botrytis. Defoliate selectively in weeks 3–4 to improve light penetration without overexposing buds.
Nutrient steering. Early flower benefits from a phosphorus and potassium bump to initiate bud set. Mid flower, sustain balanced macronutrients and monitor leaf tissue for micronutrient needs. In late flower, a gradual EC taper helps plants metabolize residual salts and can bolster flavor. Avoid aggressive late-stage nitrogen, which can suppress aroma and slow drying.
Pest and pathogen management. Dense GDP-influenced colas warrant proactive IPM. Maintain clean intakes, sticky cards, and routine scouting for mites and thrips. Biocontrols like Amblyseius swirskii or Cucumeris can help with early-stage thrips. Keep leaf surfaces dry and RH balanced to limit powdery mildew pressure, a common concern in dense canopies.
Yield expectations. Indoor yields of 450–650 g/m² are common under optimized LED systems. Skilled cultivators pushing CO2 and higher PPFD can exceed 650 g/m² with dialed phenotypes. Outdoors, 600–1200 g per plant is achievable in rich soil with full sun and strong IPM. The Big Bud influence from GDP supports heavy set when nutrition and structure are aligned.
Harvest timing. Monitor trichomes for a window of 5–15% amber with a majority cloudy for a balanced effect. For a brighter, more energetic profile, harvest closer to all-cloudy with minimal amber. For deeper body effects and enhanced dessert notes, allow more amber development in week 9+. Keep in mind that later harvests can mildly trade THC peak for thicker terpene and minor-cannabinoid expression.
Drying and curing. Target 18–21°C and 55–62% RH for 10–14 days, moving air gently without blowing directly on flowers. Once stems snap but don’t shatter, trim and jar with hygrometers to stabilize at 58–62% RH. Burp jars daily in week one, then taper to every few days for 4–8 weeks. Proper cure preserves top notes and yields a smoother, more flavorful smoke.
Clones and phenohunting. Expect some phenotypic variance with expressions leaning either toward M39’s upright, lime-green look or GDP’s purple, resin-heavy presentation. Select for the desired balance of terpene intensity, internode spacing, and disease resistance. Retain vigorous mothers that root reliably in 10–14 days with high strike rates. Consistency across runs improves marketability and product predictability.
Outdoor considerations. The cultivar’s relatively early finish suits Quebec and other northern regions with wet autumns. Choose sites with full sun and airflow to mitigate late-season molds. Mulching stabilizes root temperatures and moisture during heat waves. In cooler nights, purple hues intensify, boosting bag appeal without sacrificing resin.
Post-processing and extraction. M 39 Granddaddy’s resin density yields well in solventless and hydrocarbon systems. For live rosin, harvest at peak terpene expression and freeze immediately to preserve volatiles. Hydrocarbon extractors can accentuate grape-candy top notes while retaining a pine-skunk backbone. Proper dewaxing and gentle purge preserve flavor while ensuring stability.
Quality benchmarks and comparisons. Balanced genetics align it with the broader group of 8–10 week hybrids that combine yield and character, a timeframe often highlighted across high-performing cultivars. Structure and stem strength are adequate for mid-height canopies, comparable to other modern hybrids known for solid stems and manageable stature. Compared to classic M39, this cross tastes sweeter and finishes with richer color. Compared to GDP, it tends to be slightly faster and more forgiving under variable inputs.
Sourcing and verification. Quebec Cannabis Seeds is cited as the breeder for M 39 Granddaddy, aligning the strain with Canada’s methodical, northern-latitude breeding focus. When possible, verify genetics through trusted vendors and lab testing. Industry destinations like Leafly can provide crowdsourced profiles and regional availability, though lab certificates remain the gold standard. Maintaining grow logs and batch-level analytics supports continuous improvement across cycles.
