Magnum Auto Seeds

Presented in the Outback Seed Bank catalogue, Magnum Auto is a vigorous, sativa-dominant choice for growers seeking an autoflower with substantial height and a relatively short flowering phase. It suits intermediate growers who can manage its energetic growth, airflow and changing seasonal conditions.

Genetics & effects

Magnum Auto is described as approximately 70% sativa and 30% indica, with ruderalis ancestry supplying its autoflowering behaviour. Its exact lineage is not publicly established. Available figures place THC around 15–20% and CBD at 0–0.2%, although cannabinoid levels can vary with phenotype, environment and post-harvest handling.

Reported experiences are subjective. Some consumers describe an uplifting, energetic or creative mood, occasionally accompanied by euphoric, happy and talkative feelings. Others notice a more relaxed finish. Its aromatic profile may combine pungent citrus and pine with spicy, sweet accents, aligning with limonene, pinene and caryophyllene.

Explore autoflower seeds, high thc seeds, the Australian grow guide, and the planting calendar.

Explore autoflower seeds, high thc seeds, the Australian grow guide, and the planting calendar.

Growing in Australia

As an autoflower seed, Magnum Auto begins flowering according to age rather than a change in daylight hours. This can simplify scheduling, but its fast life cycle leaves less time to recover from major stress. Use a light, well-draining medium, avoid excessive feeding and make environmental changes gradually.

Australian conditions vary widely. Hot, dry areas call for careful moisture management and shelter from severe afternoon heat, while temperate regions often offer a broader growing window. In cool, short-season locations, prioritise warmth, strong light and protection from prolonged damp weather. Where outdoor cultivation is permitted, spring planting generally falls between September and November.

Indoor

Indoors, plants may reach up to 150 cm, so vertical space should be planned early. Gentle low-stress shaping can help maintain an even canopy, while heavy pruning may slow an autoflower during its limited vegetative period. Consistent airflow, stable temperatures and sensible humidity control help reduce mould risk around increasingly dense flowers.

Under favourable conditions, reported indoor yields reach up to 400 g/m². This is an upper estimate rather than an assured outcome; light quality, container volume, plant health and grower experience all influence the final result.

Outdoor

Outdoor plants may grow to roughly 160 cm and can produce up to 150 g per plant in suitable conditions. Select a sunny position with free-draining soil and enough airflow between plants. In exposed sites, discreet support can help branches cope with wind and flower weight. Monitor moisture closely during heatwaves, but avoid leaving the root zone continually saturated.

Its adaptability may suit hot, dry, temperate and cooler short-season climates, provided local timing is matched to dependable warmth and sunlight. Coastal humidity or extended autumn rain can increase mould pressure, making regular inspection worthwhile.

Harvest

Flowering is commonly listed at 8–9 weeks, though total seed-to-harvest time may be longer and can differ between plants. Rather than relying only on the calendar, assess flower maturity and overall plant condition. For spring starts in Australia, harvest commonly aligns with March–May for seasonal photoperiod crops, while autoflowers may finish earlier depending on sowing date. Expected yield, potency, colour and aroma remain variable.