by Nebula Haze
Today, learn why starting cannabis seedlings feels hard, until it suddenly clicks. The actions you take as a grower during weeks 1-3 are key to the best start.
Even with the best seeds and great nutrients, seedlings still need proper care.
Here’s what to focus on during your first few weeks, so cannabis plants grow fast and healthy right out the gate.
- Fast seed germination
- Seedling watering (follow a schedule)
- Give the right amount of light
How to Avoid the Most Common Seedling Mistakes
1.) Seed Germination: What to Do
Easiest method: Plant your seeds directly in their final home. This germination method is effective and fast when done right. As a bonus, you never need to transplant your plants.
Plant seeds 1 knuckle deep, then keep the soil moist and warm.
There are lots of other great germination methods, too, and each one has pros and cons. But if you’re unsure, this “plant directly in the pot” method makes things simple and reduces the chance of stressing out young plants after they germinate.
2.) Seedling Watering: What to Do
The Mistake: Overwatering is when you give too much water at a time, or too often. Underwatering is giving too little water. Improper watering is the most common seedling mistake, but the following method fixes both.
What to Do Instead: After seedlings sprout, give only a little water at a time, in a small circle around the base, every 2-3 days. Increase the amount gradually as they grow bigger (and start drinking more). For seedlings planted directly into a 3-5 gallon pot, this is a great starting schedule.
Day 1 – Give 2 cups (500ml) per plant
Day 3 – Give 2 cups (500ml) per plant
Day 6 – Give 2 cups (500ml) per plant
Day 8 – Give 3 cups (750ml) per plant
Day 11 – Give 3 cups (750ml) per plant
Day 14 – Give 4 cups (1 liter) per plant
Day 17 – Give 4 cups (1 liter) per plant
Day 20 – Give 5 cups (1.25 liters) per plant
Just a little water in a circle around the base at first.
This watering schedule keeps roots happy and healthy while avoiding over or underwatering.
3.) Grow Light: What to Do
The Mistake: Many growers unintentionally give too much or too little light for happy, healthy seedling growth. Typically the grow light is too far away or too close.
What to Do: About half the normal light intensity is a great starting point for newly-sprouted cannabis seedlings. Either keep your grow light about double the recommended distance away, or dim to half power.
Not sure? Download a free PPFD Meter app on your phone to measure light intensity, and aim for 100-300 µmol/m²/s for seedlings up to week 3.
But every light and plant is different, so watch the plants.
- Tall seedlings – If plants start looking “tall” or leggy, move the light closer.
- Short or stressed seedlings – If plants are growing totally “flat” without getting any taller, or seem stressed, move the grow light further away.
Healthy seedling
Tall seedling – move light closer
“Strong start” cannabis seedlings look about like this at 3 weeks.
Bonus tip: For the fastest growth, keep cannabis seedlings and young plants warm, but not hot (80-85°F / 26-30°C). Think bright spring day, not scorching summer heat.
Follow these three strategies to get fast-growing, healthy seedlings right out the gate. Happy seedlings grow into vigorous, thriving cannabis plants. A strong start sets you up for a strong finish!
