Germinating Weed Seeds: 8 Tips, Including the 32-Hour Rule

Germination is the moment a seed wakes up from dormancy and starts growing into a plant, and with cannabis the keys are simple: warmth, moisture, clean water and a light touch. Soak your seeds for no more than 32 hours, use distilled water, label your strains and never handle the taproot. Technically, germination is defined as "the development of a plant from a seed after a period of dormancy."

Once they're fully formed, seeds go dormant, meaning there's basically no biological activity, and they wait for the right conditions to start growing again. Stored properly, seeds can stay viable for a year or more and still produce a healthy plant.

But once a seed is dormant, how does it switch back on and grow a plant?

Dormant seeds respond to warmth and moisture, the two things a plant needs most to get going. Seeds can't tell the difference between heat and sunlight. When their surroundings get warm enough, they "assume" there's enough light to grow. Then they start "looking for" moisture. If there's enough of both, they wake up and start growing.

Only once they've sprouted into a seedling (the end of the germination stage) do they need real light to keep growing.

Keep it simple: The most popular way to germinate is also the easiest: drop your cannabis seeds in a glass of water for 24 hours, or until a taproot (the first main root) pops out. A common variation is to tuck the seeds between layers of damp paper towels.

The 32-hour rule: Seeds, like people, can drown if they get too much water, so don't leave them soaking for more than 32 hours. Keep a close eye on them and pull them out of the water as soon as they start showing a taproot. If you don't see a taproot after 24 hours, the seed may not be viable (or it may just need a few more days in a damp paper towel).

Water: Tap water works, but distilled water is better. Tap water contains things like calcium, sodium, fluoride and chlorine. In large enough amounts, those chemicals can harm tiny, fragile seeds and even keep them from germinating.

pH matters: pH (potential of hydrogen) is a numerical scale that measures how acidic or alkaline a liquid is. Checking the pH of the water you give your cannabis plants once they sprout is crucial, because they need a slightly acidic environment to digest and break down all the organic nutrients you're going to feed them.

Distilled water starts out neutral (pH 7.0), but it can absorb carbon dioxide from the air and turn slightly acidic (around pH 5.8). You can add pH adjusters to keep the water in an optimal range of 6.0 to 7.0.

Label everything: If you're only growing one strain, you don't need to label your seeds. But if you're running several, keeping track of which seed is which is a must.

The easiest way is to write the strain on a piece of masking tape and stick it on the glass you're soaking the seeds in.

No males allowed: Only female plants produce the trichome-covered buds you harvest to smoke, vape or eat.

A male cannabis plant can wreck your harvest because it can pollinate the females. Once female plants get pollinated, they start pouring their energy into making seeds instead of fattening up the buds we all know and love.

Mind the root: The taproot of a germinated cannabis seed is super fragile, so it's best not to touch it and to handle the seeds very gently when you move them from the soaking container to the growing medium (in other words, the soil). A pair of tweezers comes in handy for grabbing the seeds without touching the taproot.

Last but not least, one of the best tips for germinating and growing is to log everything in a grow journal. You need to know what day you started germinating so you don't break the 32-hour rule, and what day flowering kicked off so you can keep an eye on your plants' sex and avoid unwanted pollination. Follow these tips and your germination should go off without a hitch.