The right substrate has a massive influence on growth, nutrient uptake and yield. Complete substrate guide for every growing style.
The choice of substrate is fundamental for successful cannabis cultivation:
High quality potting soil:
Advantages:
- Easy for beginners
- Buffers pH fluctuations
- Already contains nutrients
- Contains micro-organisms
- Error-preventing
Disadvantages:
- Less control over nutrients
- May be pre-fertilised (over-fertilisation)
- Differences in quality between manufacturers
- Drainage often not optimal
- Pests/fungi possible
Recommended soil brands:
- BioBizz Light-Mix: Less pre-fertilised
- Plagron Bat-Mix: Organic, rich
- Canna Terra Professional: Balanced
- Compo Sana: Budget option
Coco-Substrate (coconut fibre):
Coco advantages:
- Excellent drainage
- High oxygen supply to the roots
- pH-neutral (6.0-6.5)
- Reusable
- Difficult to overwater
- Faster growth than soil
Coco disadvantages:
- Requires more monitoring
- Daily watering often necessary
- Needs Cal-Mag supplements
- Must be buffered before use
- Higher learning curve
Coco preparation:
- Rinse with Cal-Mag solution
- adjust pH to 6.0
- Wash out excess salts
- Expansion in warm water
- Add perlite for extra drainage
Perlite mixtures:
Perlite function:
- Dramatically improves drainage
- Increases oxygen supply
- Prevents compaction
- Structural stability over time
- Reusable
Mixing ratios:
- 70% soil + 30% perlite: Standard
- 50% Coco + 30% Perlite + 20% Vermiculite: Pro-Mix
- 60% soil + 40% perlite: Maximum drainage
- Never 100% perlite (too little support)
Organic substrates:
Compost-based mixtures:
- Own compost + perlite + vermiculite
- Worm humus as a base
- Organic additives
- Long-term nutrient release
- Building up the soil biology
Super-Soil concept:
- Complete nutrients incorporated into substrate
- Only water during the entire grow
- Build-up over several months
- Very advanced
- Best flavour results
Hydro substrates:
Expanded Clay Pebbles:
- Inert and reusable
- Excellent drainage
- Stable pH values
- Easy to clean
- Standard for hydro systems
Rockwool/rockwool:
- Sterile starting position
- Precise nutrient control
- Rapid root development
- pH preparation necessary
- Environmental concerns
Coco in Hydro:
- More natural than Rockwool
- Good buffering properties
- Can be combined with other media
- Requires more frequent flushing
Substrate mixtures for different phases:
Seedlings (0-2 weeks):
- Light, nutrient-poor mixture
- 50% coco + 30% perlite + 20% vermiculite
- Or Jiffy pellets/rockwool cubes
- Sterile conditions important
Vegetative phase:
- Standard potting soil
- Or 60% coco + 30% perlite + 10% worm humus
- Medium nutrient concentration
- Good drainage for fast growth
Flowering phase:
- Keep the same substrate
- Drainage becomes more important
- No substrate changes in flowering
- Focus on nutrient adaptation
Substrate-specific irrigation:
Soil: