Written by Ad OpsHistory and Underground Origins of the Blues Strain
Blues, often whispered about as Livers in the UK underground, is a classic British clone-only cultivar that rose to prominence in the 1990s. It circulated hand-to-hand among growers in Northern England, especially around Sheffield, at a time when UK indoor horticulture was innovating under the radar. The strain’s notoriety came from its unmistakable funk, a dense, sweetly rancid bouquet that cut through carbon filters and filled rooms.
Unlike many modern branded hybrids, Blues never launched with a flashy seed drop or a breeder’s press release. Its reputation was earned on smell, yield, and a deeply relaxing stone that made it a regional favorite. Word-of-mouth distribution built its cult status, and by the early 2000s, Blues was a fixture of UK menus alongside Cheese and various Skunk cuts.
Because Blues remained clone-only, it developed an aura of scarcity and authenticity. Growers protected mother plants for years, sometimes decades, keeping genetics stable but access limited. That conservatism preserved the strain’s identity and made it a touchstone for UK heritage cannabis.
Genetic Lineage: What We Know and the Competing Theories
The exact lineage of Blues is still debated, with no single pedigree universally accepted. The most common theory places Blues in the Skunk family, possibly as a unique Skunk selection that drifted toward sweeter, funkier esters and a more narcotic effect. Others argue for some Northern Lights influence due to the stocky structure and sedative body stone.
A minority of accounts tie the name Blues to Blueberry ancestry, but that likely confuses Blues with Blue Cheese or other Blue-named hybrids. In practice, Blues lacks the overt blueberry top notes and lavender hues typical of DJ Short Blueberry lines. Its profile leans more toward sweetly rotten fruit, fermented skunk, and sharp cheese rind than true berry.
Given the era of its emergence, a Skunk base with regional selection pressure is plausible. UK growers often selected for odor, resin, and dense buds under limited space and high humidity environments. Over many cycles, a unique chemovar with strong myrcene and caryophyllene expression could easily have stabilized into what we now call Blues.
Appearance and Plant Morphology
Blues plants typically present with broad, dark green leaflets and short internodes, a visual that aligns with indica-leaning growth. Canopies are compact, and lateral branching is robust, which makes the strain responsive to topping and screen-of-green methods. In bloom, colas stack tightly and develop substantial calyx mass.
The buds are dense, golf-ball to forearm-length clusters with thick, white-to-amber resin coverage by late flower. Under cool nights, anthocyanin expression can surface as a subtle blue-purple dusting on sugar leaves, though deep royal blues are not guaranteed. Growers often note a heavy, tacky trichome layer that gums scissors and makes for efficient hash and rosin yields.
Average indoor heights remain manageable at 60–100 cm when trained, while untrained plants can push 120–140 cm in long veg. Outdoor, in temperate climates, plants can reach 180–220 cm with adequate season length. The structure is load-bearing, but support netting is recommended during late bloom to avoid stem torque and microtears.
Aroma: The Olfactory Signature of Blues
Blues is famous for a layered, room-filling odor that mixes overripe stone fruit, tangy cheese rind, and a fermented skunk tail. The base is earthy and musky, with a warm, slightly sweet undercurrent that drifts into savory territory as flowers cure. In fresh grind, many noses catch hints of tangy apricot compote mingled with funky cream and wet soil.
Dominant terpenes like myrcene and beta-caryophyllene are consistent drivers of the profile, with humulene and limonene often contributing herbal hops and citrus zest. Leafly guidance on terpene shopping notes that a strain’s dominant terpenes will largely telegraph its smell and mouthfeel, and Blues is a textbook example of myrcene-forward herb announcing itself from a sealed jar. Air filtration becomes essential; activated carbon with a high iodine number and robust air changes per hour is advised.
Well-grown phenotypes can read at 8–9 out of 10 on a proprietary aroma intensity scale used by some UK growers, and terpene totals can surpass 2% by dry weight under optimal conditions. Dutch Passion has highlighted that high-terpene cultivars paired with high THC create a terpene explosion, and Blues often plays in that territory. Expect the room note to linger for hours after a joint is finished, especially in closed spaces.
Flavor: From Inhale to Exhale
The inhale brings a sweet, earthy rush with a syrupy, fermented fruit tone that separates Blues from simpler skunk profiles. Mid-palate, a creamy, tangy dairy impression emerges, reminiscent of aged cheese and yeasty bread. On the exhale, peppery caryophyllene prickles the tongue while humulene supplies a green, hop-like dryness.
Vaporization between 175–190°C accentuates the fruit esters and makes limonene and linalool more apparent. Combustion, by contrast, heightens the funk and savory edges, emphasizing the cheese-rind side of the profile. A full cure of 21–28 days in stable 58–62% relative humidity jars consolidates sweetness and smooths the throat hit.
In blind tastings, experienced consumers often identify Blues by the aftertaste: a lingering, sweet-funky film paired with a pepper-spice tail. That finish remains distinct for 10–15 minutes after consumption, and water does little to wash it away. Pairing suggestions include citrus seltzer to brighten the palate or a mild black tea to complement the caryophyllene spice.
Cannabinoid Profile and Potency
While lab data for the original UK clone is sparse, reported potency ranges for Blues commonly fall between 18–24% THC by dry weight. CBD content is typically minimal, often under 0.5%, with occasional outliers approaching 1%. Minor cannabinoids like CBG can appear around 0.3–0.8%, and trace THCV is sometimes detectable at sub-0.2% levels.
Total cannabinoid content in flower often registers in the low-to-mid 20% range when grown under high-intensity lighting and dialed-in nutrition. Concentrates made from Blues trim and buds can exceed 65–75% THC in hydrocarbon extracts, with live rosin squishes routinely hitting 65% total cannabinoids when produced from fresh-frozen input. These numbers are within modern expectations for potent indica-leaning cultivars.
For context, the broader blue family has notable night-use representatives like Blue God, which Leafly reviewers consistently describe as very relaxing and best consumed late. That aligns with Blues’ typical myrcene-forward chemotype and heavy body feel. Consumers should approach dosing thoughtfully; 5–10 mg THC in edibles derived from Blues can feel stronger than the milligrams suggest due to sedative synergy with terpenes.
Terpene Profile and Chemovar Insights
Myrcene is commonly the lead terpene in Blues, often ranging from 0.5–1.2% by weight when well grown. Beta-caryophyllene frequently follows at 0.3–0.6%, contributing pepper and potential CB2 receptor activity. Humulene shows up in the 0.1–0.3% band, adding herbal dryness, while limonene and linalool may contribute 0.1–0.5% and 0.05–0.2%, respectively.
Leafly’s cannabis education highlights myrcene as the most abundant terpene in cannabis overall and associates it with sedative and muscle-relaxing effects. That dovetails with Blues’ evening reputation, where the combination of myrcene and caryophyllene often yields a weighted, couch-friendly feel. Total terpene loads for dialed-in runs can hit 2.0–3.0% of dry weight, which is considered high and consistent with the terpene explosion tier outlined by Dutch Passion for standout cultivars.
It is important to view Blues as a chemovar rather than a monolith; environmental factors can shift the dominant terpene expression. Cooler night temps can increase perceived sweetness and berry-adjacent esters without turning the profile into a true blueberry. Grown hot and fast, humulene can drop and the aroma may flatten to a simpler skunk-earth with less nuanced sweetness.
Experiential Effects and Consumer Reports
The onset typically arrives within 5–10 minutes of inhalation, beginning behind the eyes and spreading through the neck and shoulders. A warm heaviness follows, often described as a weighted blanket effect that quiets physical agitation. Mental chatter tends to slow, and focus drifts inward, making Blues a natural fit for unwinding and media consumption.
Peak effects for inhalation last about 90–150 minutes, with a gentle tail-off rather than a sudden fade. Many users report profound muscle relaxation and a reduction in minor aches, aligning with reports that similar blue indicas like Blue Moonshine lean sleepy and relaxed while occasionally causing dry eyes and mouth. Hydration and eye drops reduce the discomfort, and pacing doses minimizes dizziness reported by some with Blue Moonshine and, by analogy, heavier blues.
Time-of-day matters: this is widely considered an evening or night strain. Leafly reviewers describe Blue God as best consumed late due to its sedative feel, and Blues sits in that same night-use lane. For creativity, the first 30 minutes can offer a calm, cinematic sensory enhancement before the body load takes center stage.
Potential Medical Uses and Considerations
Patients frequently explore Blues for sleep support, especially for reducing sleep onset latency after stressful days. The myrcene-forward profile, as Leafly notes, is associated with muscle relaxation, and many anecdotal reports cite relief from tension headaches and neck tightness. Those managing chronic pain, including lower back pain and arthritic discomfort, often find the body load beneficial in the evening.
Anxiety relief can be meaningful for some, particularly where ruminative thought patterns are a problem. However, high doses can become overwhelming for sensitive individuals, so titration is key. Starting with 1–2 inhalations or 2.5–5 mg oral doses can help gauge response before building to therapeutic ranges of 10–20 mg for experienced patients.
Appetite stimulation is noticeable, and Blues can be useful during appetite-suppressed periods or convalescence. As with many potent indicas, dry mouth and eyes are common, and rare users report transient dizziness at peak blood THC levels. This information is educational, not medical advice; patients should consult healthcare providers, particularly when combining cannabinoids with sedatives, antidepressants, or blood pressure medications.
Comprehensive Cultivation Guide: From Clone to Cure
Genetics and sourcing: The original Blues is a UK clone-only cut. Seed lines labeled Blues may be crosses or approximations; verify provenance from trusted circles. If starting from seed, select for the phenotype with the classic sweet-funk nose, dense nug structure, and myrcene-forward chemotype.
Environment and planning: Indoors, Blues thrives in 24–26°C daytime and 18–21°C nighttime temperatures. Relative humidity should sit at 60–70% in veg, 45–50% in mid flower, and 38–42% during the final 10 days to curb botrytis risk. Aim for a flower VPD of 1.2–1.6 kPa and stable airflow with 30–40 complete air exchanges per hour in small tents.
Lighting and DLI: Vegetative growth responds well to 300–500 PPFD for 18 hours daily, targeting a daily light integral of 20–30 mol m−2 d−1. In bloom, raise intensity to 800–1,000 PPFD for 12 hours, pushing 34–43 mol m−2 d−1. CO2 supplementation at 1,000–1,200 ppm can increase biomass by 20–30% and improve terpene retention if temperatures rise to 27–29°C in flower.
Medium and nutrition: In coco, maintain pH 5.7–6.0 and EC 1.2–1.6 in veg, rising to EC 1.8–2.2 during peak bloom. In living soil, aim for a pH 6.2–6.5 and let biology deliver nutrients, top-dressing with 2–4% nitrogen in early veg and shifting to a phosphorus-potassium bias in weeks 3–7 of flower. Calcium and magnesium supplementation is often necessary under high-intensity LEDs, delivering 100–150 ppm Ca and 40–60 ppm Mg.
Training and canopy: Blues’ bushy structure excels in SCROG. Top once at the fifth node, then LST branches to fill 70–80% of the net before flip. Expect 20–30% stretch; set the net height at 20–30 cm above the media and add a second trellis in week 3 of bloom for lateral support.
Irrigation strategy: In coco, feed to 10–20% runoff once daily in early veg, moving to two feeds daily in late veg and early flower. In high-PPFD flower, three smaller irrigations per lights-on cycle can stabilize EC and keep root zone oxygenated. In soil, water to full saturation then wait until the top 2–3 cm are dry; overwatering invites root pathogens and dulls terpene production.
Flowering timeline: Most Blues phenotypes finish in 56–63 days of 12/12, with some going 65 days for maximum resin and a more narcotic effect. Harvest timing can tune effects: 5–10% amber trichomes for a balanced stone, 15–25% amber for deeper sedation. Under optimal care, expect indoor yields of 450–600 g m−2; aggressive dialing with CO2 can push 650+ g m−2.
Pest and disease management: Dense Blues colas are susceptible to botrytis in weeks 7–9. Keep leaf surface temperatures steady, increase air movement within the canopy, and defoliate lightly in weeks 3 and 6 to open bud sites. Implement IPM with weekly inspections, yellow sticky cards, and beneficials like Neoseiulus californicus for mite suppression.
Aroma control: The smell is penetrating. Use oversized carbon filters rated for at least 1.5–2 times your fan CFM, and consider a pre-filter to extend service life. Seal passive intakes and create negative pressure to prevent fugitive odors; this is not the strain to grow without filtration.
Color expression: While dubbed Blues, deep blue hues are conditional. Nighttime temps in late flower around 15–18°C can coax anthocyanins, but do not sacrifice plant health for color. The more important indicator of quality is terpene richness and resin clarity, not pigment.
Harvest and processing: Wet trim the largest fan leaves, then hang whole or branch sections at 18–20°C and 55–60% RH for 10–14 days. Once small stems snap and bigger stems bend with a crackle, jar at 58–62% RH. Burp jars daily for 10 minutes during the first week, then weekly for 3–4 weeks; a 21–28 day cure markedly improves sweetness and smoothness.
Hash and rosin: Blues’ greasy resin heads produce well in ice water extraction, often returning 4–6% yield from dried material and 3–4% from fresh-frozen. The 73–120 micron range is typically the sweet spot for bag pulls. Pressing bubble hash at 90–95°C for 1–2 minutes preserves the funk and yields a thick, spicy-sweet rosin.
Outdoor considerations: In temperate regions, plant after frost and expect harvest in late September to early October depending on latitude. Space plants 1.5–2.0 meters apart to maximize airflow, and prune lower growth to reduce splash-up and microclimate humidity. Outdoor yields of 500–800 g per plant are common with 6–8 hours of direct sun and consistent feeding.
Comparative context: Blue Dream, another member of the broader blue family, is famous for large indoor yields, and yields from Blues can be competitive when SCROGged though generally denser and shorter. Dutch Passion notes that many blue-named lines carry indica traits, and Blues conforms with stout structure and sedative lean. If desired, blending cured Blues with a limonene-forward sativa in a 70:30 ratio, a practice Dutch Passion has discussed in the context of strain blending, can broaden the effect spectrum while preserving the core funk.
