Guava Runtz Auto by Fast Buds

When a seed bank crosses two award-winning varieties, the interesting part is seeing what each one contributes. Guava Runtz Auto brings together the Guava Auto RF3, champion of the latest Autoflower World Cup, with Mephisto Genetics' Mango Runtz F5, another regular on the podium in 2024 and 2025. The result is a self-contained F1 hybrid autoflower that Fast Buds has placed in its Champions Line.

Two champions in one F1

From Mango Runtz comes the compact, manageable structure; from Guava RF3, the growth energy and stability that the bank has been refining over eight generations. The combination delivers typical F1 hybrid vigour: plants that start strong and produce dense flowers without getting out of hand.

The population is homogeneous in behaviour, but not in appearance. And that's where its most striking trait lies.

Two phenotypes, one nearly black

The line expresses two main phenotypes with very similar terpene profiles. One leans towards dark colouring, almost black; the other stays green and develops darker tones towards the end of the cycle. Both share vigour, bud density and consistent structure, so what changes from plant to plant is the aesthetics, not the yield.

Cultivation and harvest

The cycle closes in 8–9 weeks and the plant sits between 70 and 120 cm tall. Its XXL classification comes from production: 450–600 g/m² indoors and 60 to 300 g per plant outdoors. It works indoors, outdoors, in a greenhouse and under mixed light, so it performs equally in a grow tent or on a patio.

By the numbers and structure it fits among the XXL Autoflowering Seeds, with the advantage of not needing complicated training to hit those numbers.

Aroma and effect

The aromatic profile takes centre stage: guava and mango up front over a sweet candy base, with layered background notes that carry through from bud to finished product. It's one you notice when you open the jar.

The effect reported by the bank's growers is uplifting and sociable, with a creative edge at first and a body relaxation that follows. If you move in this family, the catalogue also has other Runtz varieties like the White Runtz from Barney's Farm.

Technical Specifications for Guava Runtz Auto

• Seed bank: Fast Buds
• Genetics: Guava Auto RF3 × Mango Runtz F5 Auto
• Seed type: Feminised autoflower, F1 hybrid
• Genotype: 50% Indica / 50% Sativa
• THC: Up to 30%
• CBD: Less than 1%
• Height: 70–120 cm
• Indoor yield: 450–600 g/m²
• Outdoor yield: 60–300 g/plant
• Flowering time: 8–9 weeks
• Size: XXL
• Phenotypes: Two expressions, one with almost black colouring
• Flavour profile: Guava, mango, sweet candy
• Growing area: Indoors, outdoors, greenhouse and mixed light
• Formats: 1, 3, 5 and 10 seeds