Sex determination prevents unwanted pollination. Early detection of male and hermaphrodite plants saves harvests.
Determining cannabis gender early and safely is critical for every grower:
Why sex determination is important:
Unpollinated vs. pollinated flowers:
- Female, unpollinated flowers = Sinsemilla (without seeds)
- Highest THC concentration
- Pollinated flowers = energy goes into seed production
- THC content drops drastically after pollination
Space optimisation:
- Male plants take up valuable space
- Early removal = more space for female plants
- Rare problem with feminised seeds
- Regular seeds: 50% male on average
Gender characteristics in detail:
Female cannabis plants:
Early signs (3-6 weeks):
- Two white hairs (pistils) on nodes
- V-shaped calyx with opening
- Pistils grow out of calyx
- Usually more compact, bushier growth
Developed female characteristics:
- Cluster of white pistils
- Calyx swells without seeds
- Trichomes develop on calyx
- Flower formation at 12/12 light cycle
Male cannabis plants:
Early signs (3-6 weeks):
- Small green balls on nodes
- No pistils or hairs
- Balls hanging from small stems
- Often faster, higher growth
Developed male characteristics:
- Pollen sacs open
- Yellow dust (pollen) visible
- Flower clusters hang downwards
- Strong, unpleasant odour
Hermaphrodite (hermaphrodite):
Signs of hermaphrodites:
- Both pistils and pollen sacs
- Often male flowers hidden in female flowers
- "Bananas" (yellow stamens) in flowers
- Mostly stress-induced
Stress factors for hermaphrodites:
- Light leaks during the dark phase
- Extreme temperatures
- Nutrient stress or pH problems
- Damage or unclean techniques
- Genetic predisposition
Timing of sex determination:
Photoperiodic plants:
- First signs: 4-6 weeks vegetative
- Clearly recognisable: 1-2 weeks after 12/12 changeover
- Pre-flowers: Small signs of sex before flowering
- Latest: Week 2-3 of the flowering phase
Autoflower plants:
- First signs: 3-4 weeks after germination
- Sex shows automatically
- No light cycle adjustment necessary
- Often recognisable earlier than photoperiodic plants
Identification techniques:
Daily inspection:
- Check all nodes every day
- Especially upper nodes affected first
- Magnifying glass (30x) for small details
- Inspect in the morning in good light
Photo documentation:
- Photograph suspicious areas
- Compare with reference images
- Time series for development
- Community forum for unsafe cases
Stress test for pre-flowering:
- 12/12 light cycle for 1-2 weeks
- Sex shows up faster
- Back to 18/6 after identification
- Only for photoperiodic plants
Immediate measures after identification:
Male plants:
- Remove and dispose of IMMEDIATELY
- Do not compost (pollen survives)
- Act before pollen release
- Check other plants for pollen contamination
Suspected hermaphrodites: