Cannabis genetics vary widely due to their origins and breeding history, influencing requirements for light, humidity, nutrients, and more. This updated guide covers germination, light and intensity differences, humidity considerations, the evolution from landraces to modern strains, fertilization timing in veg and flower phases, and growing multiple strains together. We've incorporated 2025 insights from leading breeders, including efficiency improvements in LED lighting and sustainable nutrient practices, to provide practical advice for both beginners and experienced cultivators.
Best way to germinate cannabis seeds
Germination is the first step for any seed-based grow, and genetics play no role in the method—fresh, high-quality seeds from reputable sources like Suzy Seeds achieve consistent results with the same approach. The most reliable technique is the water glass method, detailed in our germination guide.
Place seeds in room-temperature water (20-25°C) for 12-24 hours until they sink or split. Transfer to damp paper towels in a warm, dark environment (20-25°C). Roots typically emerge in 1-3 days, with a success rate exceeding 95% for viable seeds.
For added security against mold in humid conditions, a diluted hydrogen peroxide solution (1:10 with water) can be used, a practice gaining traction in 2025 for its oxygenation benefits without harming embryos. Test 2-3 seeds per batch to confirm viability before committing your full order.
Light and Intensity: Tailored to Genetic Origins
Light requirements differ based on whether a strain is sativa-dominant (from equatorial regions with intense sun), indica-dominant (adapted to shorter, cooler days), or hybrid/autoflowering (a balanced compromise).
Indoor Growing
High-pressure sodium (HPS) lights remain effective for maximum yields due to their red-spectrum output, but 2025 LED advancements—now averaging 2.8 µmol/J efficiency—offer better energy savings and heat management. Sativa-leaning strains like Super Silver Haze require higher intensity (800-1000 µmol/m²/s in flower) to prevent stretching, while indicas like Northern Light perform optimally at 600-800 µmol/m²/s.
Maintain temperatures between 20-30°C; in colder setups, supplemental heating prevents drops below 20°C, which can stress all genetics.
Dimmable LEDs are a smart pick for hybrids, with trials showing 15% yield bumps from gradual ramps.
Outdoor: Harnessing the Sun (With a Nudge for Genetics)
Natural sunlight is unbeatable, but your latitude and strain heritage dictate tweaks. Sativas love long days (14+ hours), but in shorter northern seasons, haze genetics (e.g., Super Silver Haze) benefit from blackout tarps to kick off 12/12 cycles early—finishes the crop before fall dampness invites mold. Harvest at 70-80% browned pistils; loupe it for precision.
| Genetics | Flower Intensity (µmol/m²/s, Indoor) | Spectrum Preference | Outdoor Tip |
| Sativa-dominant | 800-1000 | Blue-dominant | Blackout early for timely finnish |
| Indica-dominant | 600-800 | Red-dominant | Natural short days |
| Hybrids/Autos | 700 | Full-spectrum | Monitor light daily |
Humidity: Matching Climate to Genetics
Humidity levels must align with a strain's heritage—equatorial sativas tolerate higher moisture, while high-altitude indicas prefer drier air.Veg stage: 60-70% RH for all, promoting healthy root development. Flower stage: Sativas handle 50-60% (reducing to 40-50% late), indicas 40-50% (down to 30% to prevent rot). In 2025, with variable weather patterns, dehumidifiers are essential for autos in humid zones, as ruderalis genetics are less forgiving of excess moisture.
Choose accordingly: Holland's Super Bud suits wet northern climates, while Tangerina Punch excels in drier Mediterranean areas. Ventilation is key—oscillating fans prevent stagnant air.
From landraces to hyped up strains
The cannabis landscape has changed rapidly, going from just landraces to hyped up strains. In an earlier blogpost, we’ve gone into detail about one of these landraces: Hindu Kush. As you might guess, this is where the original Kush genetics originate from.
But since we’ve started breeding cannabis, different genetics have come and gone. Like critical genetics which is very common in breeding programs, but lately cultivars like Gorilla Glue and Zkittlez.
All this breeding and using nutrients, makes that genetics lean towards different needs.
Sativas are based on landraces originating from countries with a lot of light and high light intensity. Naturally, this is also what these genetics prefer.
More Indica leaning genetics will thrive better in colder climates, shorter days and thus light.
Hybrids, which most cannabis genetics nowadays are, are a combination of Sativa and Indica genetics and thus will prefer more of a balance.
This goes for indoor and outdoor growing.
Nutrients vary by phase and genetics—start with quality soil to minimize issues.
Veg Phase
Focus on nitrogen for foliage: Half-strength NPK every 7-10 days. Sativas benefit from phosphorus boosts for root length, while indicas need less to avoid legginess. Autos rely on soil alone. In 2025, mycorrhizal inoculants (fungi-root partnerships) enhance uptake, reducing feed frequency by 20-30%—ideal for beginners.
Flower Phase
Shift to phosphorus-potassium for buds: Full strength every 10-14 days. Foliar feeding (spray on leaves) once weekly in early flower minimizes overfert risk—apply 30 minutes before lights-on indoors or sunrise outdoors. Autos skip flower feeds entirely. Flush with plain water 2 weeks pre-harvest.
Compost teas cut synthetics while boosting terpenes—pH 6.0-6.5 remains non-negotiable
Interested in autoflowering seeds? Check out our blogpost on why you should consider autoflowering cannabis seeds.
Different strains in one grow
But what if you want to grow different genetics at once for different needs of your own? There are some pros and cons to this.
In short:
Pros:
- Learning quickly
- Yield can be increased
- More variety
Cons:
- Labor intensive
- Space issues
- Harvest times
To go into more detail about the pros, let’s start with learning quicker. Yes, it is more difficult to grow different strains in one grow, but it’s also the best practice. You could also see this as a con, depending on your perspective. Because you’re growing different strains, you can opt to choose for a balance between plants with a high yield and plants that are more flavorful, but yield less. As such, this will also increase your variety. And after all, variety is the spice of life.
About the cons: yes, it is more labor intensive having to check up on different plants. You will have to, because you might run into space issues. You don’t want plants to reach out or over and through other plants. Plants are very sensitive to this. Make sure there’s always some room left for when you have to move them more apart. Harvest times is mentioned here as a con, but depending on your perspective could also be named as a pro. You will not harvest all of your different plants at the same time, but depending on your reasons to grow cannabis, this could be a huge advantage. Or disadvantage, of course.
Final Thoughts
Understanding genetic needs—from germination to multi-strain management—leads to consistent, high-quality harvests. Explore Suzy strains like Leila Kush for indica reliability or Super Silver Haze for sativa vigor. For more, check our flowering guide. Questions on your setup? Share in the comments.
