Short answer
Most germination failures come down to three variables: temperature, moisture, and handling. Cannabis seeds crack fastest between 70°F and 85°F, in a medium that stays damp rather than wet, with minimal interference. Meet those conditions and a viable seed usually shows a taproot in 3 to 7 days. If nothing has happened by day 10, something in the setup is off, or the seed was never viable.
cannabis germination guide for beginners
Nothing after five days
Wait, then check. Patience beats poking. Every time you dig a seed out to see what's going on, you risk snapping the taproot that was about to appear. Give it a full week before you investigate, and when you do, lift the seed with a spoon or tweezers rather than your fingers.
Temperature is the usual suspect
Cold is the most common killer and the hardest to notice. A kitchen counter in winter sits around 65°F, which is comfortable for you and sluggish for a seed. A basement floor is worse. Seeds that sit cold for a week don't just stall; they rot. A seedling heat mat set to 78°F fixes this in an afternoon. Put a thermometer next to the seeds, not across the room, and trust that reading.
Too hot is possible but rarer. Above 90°F you start cooking the embryo and drying the medium out between checks.
Wet versus damp
Overwatering does more damage than underwatering during germination. A seed needs oxygen as much as water, and one sitting in a puddle is suffocating. In the paper towel method, the towel should feel like a wrung-out sponge. If water runs when you tilt the bag, it's too wet. In soil or a plug, the medium should be moist through but never glossy.
Symptoms of too much water: a seed that swells, darkens, and turns soft. Symptoms of too little: a seed that stays hard and dry, or a taproot that appears and then stalls with a brown tip.
Depth and orientation
Plant a quarter inch to half inch deep. If you can see the seed from above, it's too shallow. Deeper than an inch and a small seed may burn through its stored energy before the shoot reaches light.
Angle gets argued about more than it deserves. Point up, point down, on its side; the root figures it out. What matters is that you don't pack the medium down hard. Loose, airy soil lets the shoot push through.
Damping off and white fuzz
If a sprout emerges and then collapses at the base, that's damping off, a fungal problem caused by Pythium or Rhizoctonia. It shows up in cool, soggy, still conditions. There's no rescue once the stem pinches. Prevent it with clean containers, fresh medium, and some airflow. A small fan on low, not pointed straight at the seedlings, keeps the surface from staying wet.
White fuzz on the seed itself is usually mold from a too-wet paper towel. Rinse the seed in a dilute hydrogen peroxide solution, roughly one part 3% peroxide to four parts water, then restart in fresh materials.
Old seeds and tough shells
Seed viability drops with age and poor storage. Seeds kept cool, dark, and dry last for years. Seeds left in a warm drawer for two summers often won't. For stubborn older seeds, scuff the shell along its seam with fine sandpaper or the edge of a nail file, then soak for 12 to 24 hours in water with a splash of hydrogen peroxide. This softens the coat and gives the embryo a head start.
Don't touch the taproot
Once the white root appears, that's your cue to plant it. Root down, and handle the seed shell only if you have to move it. The taproot is fragile, and a broken tip usually means a dead seedling. If you germinated in a paper towel, plant the whole thing root-first into a small hole and cover it gently. Don't press.
Light and the first 48 hours
Seeds don't need light to germinate, but they need it the moment the sprout breaks the surface. A seedling that stretches for light in a dark room gets leggy and weak. Put them under a mild light source as soon as the head appears, and keep it close enough to stop stretching without cooking them.
If the seed shell stays stuck on the leaves, mist it and wait a day. Pulling it off takes the cotyledons with it more often than not.
When to give up and start over
By day 10 to 14, you should know. Squeeze the seed lightly between your fingers. Mushy and dark means dead. Firm and pale means it might still go, so give it a few more days. Anything that has gone soft, fuzzy, or smells off goes in the trash.
Then reset the whole setup: fresh medium, clean water, correct temperature, and one change at a time. Chasing five fixes at once tells you nothing about which one worked.