Want to grow strong, healthy Sativa plants from seed?
The seedling stage is the most critical stage of a cannabis plant’s life. Screw this stage up and your entire grow will suffer. Do this stage right and you’ll lay the foundation for a plant that will provide you with huge yields in the future.
Here’s the truth most growers miss:
Seedlings require very little. But what they DO require MUST be just right. Three critical components are:
- Light
- Water
- Humidity
Miss-adjust any of these and you’ll have stretched, leggy or dead seedlings. Time to break down how to perfect each setting.
Here’s What’s Inside:
- Why Sativa Seedlings Are Different
- Getting Light Right For Sativa Seedlings
- The Watering Rules That Actually Work
- Humidity Levels That Keep Seedlings Healthy
- Common Sativa Seedling Mistakes To Avoid
Why Sativa Seedlings Are Different
Sativa strains are tropical by nature.
They hail from Thailand, Columbia and Mexico – so they LOVE warm temperatures and high humidity. Keep that in mind before you start.
Compared to their Indica cousins, Sativa seedlings:
- Grow taller and lankier
- Take longer to mature
- Prefer warmer temperatures
- Need slightly higher humidity
When growing Sativa seeds, always source from trusted seed banks. Doing so will ensure you get the highest germination rates possible right from the start. Fresh, quality seeds can have viability rates of 95%+. While older seeds, say 5-years-old, can go down to 50% viability. Translation: Where you buy your Sativa seeds is just as important as how you nurture them.
Marijuana industry is booming as well. Cannabis sales reach about $34 billion annually, leading to more people starting to grow at home than previous years. Most of them screw up the seedling stage. Don’t become another statistic.
Getting Light Right for Sativa Seedlings
Light is the #1 thing you need to dial in.
Too much light and your seedlings will scorch. Too little light and they will grow tall and leggy, weak and spindly stems that fall over at the slightest gust of wind.
Here’s what works:
During the first 1-2 weeks, seedlings don’t need very bright light. A CFL bulb or low power LED will work fine. Place light about 12-18″ from the top of the plant.
Watch the seedling closely. If it’s:
- Stretching upwards: light is too far away
- Yellowing or burning: light is too close
- Standing tall and stocky: you’ve got it right
Keep your Sativa seedlings under 18-24 hours of light a day. At this stage most growers will use an 18/6 schedule. This means 18 hours on and 6 hours off. Giving your plant a slight rest and helps you save a little on your electric bill.
LED grow lights are the best option for new growers. They:
- Run cool (less risk of burning)
- Use less electricity
- Have full spectrum options
If you are using HID lighting, keep it far away. Minimum of 50cm away from seedling. They produce heat and will cook seedlings in hours.
The Watering Rules That Actually Work
This is where most people kill their seedlings.
New growers tend to give their plants too much water. Sativa starters have small root systems, and they can’t metabolize much water as a seedling. More water DOES NOT mean more growth.
Here’s the rule:
Water lightly. Water rarely.
Wait until the top inch of soil is dry before watering again. Typically, only a spray bottle is needed in week one. Keep soil moist — not drowned.
How do you know when to water?
- Pick up the pot. If it feels light, water it.
- Stick a finger in the soil. If the top inch is dry, water.
- Look at the leaves. Drooping can mean too much OR too little water.
Use tepid water, not cold. Cold water will stun the roots and inhibit growth. Filtered or distilled water is ideal since tap water usually has chlorine that can kill young roots.
TIP: Water at the base of the seedling, try not to get water on the stem. If you get the stem wet it can cause damping off a fungal disease that kills seedlings in one night.
Humidity Levels That Keep Seedlings Healthy
Sativa seedlings are humidity lovers.
They grow in the wild in tropical areas that have consistent humidity year round. Try to mimic this environment at home for the best start.
The optimal humidity level for cannabis seedlings is 65-80%. The higher the better during the first week, and then decrease slowly as they mature.
Here’s a simple humidity schedule to follow:
- Days 1-7: 75-80% humidity
- Days 7-14: 70-75% humidity
- Days 14-21: 65-70% humidity
- Day 21+: drop to 60% and continue lowering
So how do you reach these levels of humidity? Use a humidity dome over your seedlings. Humidity domes are clear plastic covers that hold in moisture and greenhouse your plant.
If you don’t have a humidity dome:
- Cut a 2-litre soda bottle in half and use it as a dome
- Use a clear plastic bag with a few holes for air
- Run a small humidifier in your grow space
And don’t neglect temperature. Sativa seedlings love it hot — about 22-25° Celsius during the day, and a bit cooler at night.
Common Sativa Seedling Mistakes to Avoid
Let’s go over the biggest mistakes growers make.
Mistake #1: Buying cheap seeds. Bad seed = bad seedlings. It’s just fact. Purchase seeds from a well-known seed bank that guarantees their germination rates.
Mistake #2: Too much nutrients too soon. Don’t feed seedlings for the first 2-3 weeks. The seed contains everything the plant needs to get growing. Introducing nutrients this early will burn the plant up – literally. You’ll see nutrient burn as brown crispy leaf tips.
Mistake #3: Transplanting too early. Wait until there are at least 3-4 sets of true leaves before putting your seedling into a larger pot. Transplanting too early shocks their roots and sets back their growth for weeks.
Mistake #4: Not providing airflow. Seedlings grow stronger when provided with a little breeze. You can put a small fan on its lowest setting. Seedlings that don’t get enough airflow will have weak, floppy stems.
Mistake #5: Failure to Label Your Plants. If you are growing more than one strain of plant, LABEL THEM DAY ONE. You will kick yourself when harvest time comes and you forgot to label your plants.
Bringing It All Together
Sativa seedling care isn’t complicated. It just requires attention to detail.
Get the three biggies right – light, water and humidity – and the rest of it pretty much looks after itself. In summary:
- Use gentle light (CFL or LED) at 12-18 inches away
- Water lightly and only when the top inch of soil is dry
- Keep humidity at 65-80% during the seedling stage
- Maintain temperatures around 22-25°C
- Avoid the 5 common mistakes most growers make
The seedling phase only lasts for 2-3 weeks. However, everything you do during this time will affect the grow. Take your time to learn how to do it right and you’ll be rewarded with healthy, vigorous Sativas that yield huge amounts come harvest time.
Happy growing!
