Purple Arrow Auto

Here is what Purple Arrow delivers at harvest: up to 300 g/m2 per square metre indoors, up to 300 g/plant per plant outdoors in UK conditions, with resin production peaking at 21% THC. Those numbers tell a story when you work backwards through the 50-60 days window. The bulk of your final weight accumulates during weeks 5 through 8 — a period where the 79/21 genetics stack calyxes rapidly and trichome coverage shifts from scattered to frosted. UK outdoor growers targeting an early-October harvest should count back from their local first-frost date accordingly, aiming for buds to enter this critical fattening stage through late August and early September while daylight is still generous.

To reach the upper end of this strain's yield potential (up to 300 g/m2 indoors, up to 300 g/plant outdoors), focus your efforts on three critical windows during the 50-60 days period.

Window 1: The first 10 days after flowering begins. Stretch management determines canopy uniformity, which directly impacts light distribution and final yield. Expect modest stretch of 20-30% — a quick defoliation of lower fan leaves at day 7 redirects energy to developing bud sites.

Window 2: Weeks 3-5 of bloom. Myrcene terpene biosynthesis ramps up during this period. Maintain a day/night temperature differential of at least 6-8°C to encourage terpene accumulation — UK autumn evenings (September-October) naturally provide this swing for outdoor growers. Indoor cultivators should target 25-26°C during lights-on and 18-20°C during lights-off. Supplement with potassium-heavy bloom nutrients at EC 1.6-1.8.

Window 3: Final 10-14 days before harvest. Cease all nutrient input and flush with pH-adjusted water. Monitor trichomes daily with a 60x jeweller's loupe — harvest at 15-20% amber for the full-bodied effect this genetics is known for. UK outdoor growers: this window typically falls from late September through mid-October.

Flowering: 50-60 days. Indoor yield: up to 300 g/m2. Outdoor yield: up to 300 g/plant. Rated intermediate difficulty.

UK customers report creative, calm as the defining characteristics, and our experience aligns with that consensus. At 21% THC, this indica sits in a potency bracket where dosage control genuinely matters. A single bowl in a vaporiser at 185°C produces a manageable, pleasant body relaxation with intact mental function — perfect for winding down at the end of a long day. Increasing the dose shifts the experience firmly towards physical sedation, and many users find this their preferred nighttime cultivar during the cooler months. The Myrcene/Humulene terpene combination imparts a flavour that lingers on the palate — earthy and slightly sweet with a fruit-like finish.

Ideal settings: quiet evenings, film nights, post-exercise recovery, and sleep preparation.

Primary: Myrcene · Secondary: Humulene · Tertiary: Linalool. Flavour translation from flower to vapour and smoke differs with this terpene combination. Low-temperature vaporisation (180-188°C) highlights the humulene and linalool notes whilst keeping myrcene as a foundation. Higher temperatures or combustion flatten the profile into a single-note experience — still pleasant, but lacking the complexity that makes this cultivar genuinely interesting to those who appreciate flavour.

Purple Arrow suits growers with fundamental skills already established. You should understand pH management, basic nutrient ratios, and light cycle requirements before committing to this cultivar — it will not hold your hand, but it will not punish minor mistakes harshly either. Autoflowering genetics eliminate the need for light cycle manipulation, making this ideal for UK balcony growers, guerrilla setups, and anyone wanting a fast turnaround from seed to harvest. The UK growing season (April through October) accommodates the 50-60 days bloom period comfortably for outdoor cultivators across the country. Shipped discreetly across the UK with our germination guarantee.