How to: Germinate Cannabis Seeds

What is the best way to germinate cannabis seeds?

Basically, you’ll need two saucers or plates and some moist tissue.

– Line the bottom of the first plate with a few layers of wet tissue and drain any excess water from the plate.
– Next, place your seeds on top of the tissue, allowing each seed as much space as possible.
– Place another few layers of moist tissue on top of the seeds, again allowing excess water to drain off.
– Lastly, cover everything with the second plate, upside down, to form a ‘clam-shell’ shape – this will create the dark, moist environment necessary for germination.
– Place the plates somewhere warm (21ºC) and away from direct light.

Your seeds are now on their way to germination.

– Check your seeds every day to ensure that the tissue does not dry out. Spray the tissues with water if necessary.
– Within a few days you should see the first seeds open and a root emerge. It is uncommon, but some seeds may take up to 10 days or even two weeks to open.
– When the first few millimeters of root have emerged from an open seed, you should then CAREFULLY (preferably with tweezers) transfer it to a small container of growing medium (soil or rockwool). Make a hole 2-3mm (max 5mm) deep in the medium, place your seed, root first, into the hole and cover over.
– Your seedling should emerge from the medium within 1 to 3 days.

What are the best conditions for seedlings?

Seedlings will benefit from a bright (though not, initially, under lamps or in direct sunlight), warm (21ºC) and humid environment. A propagator is the easiest way to achieve these conditions. A propagator may be bought or built. It is, basically, a box with a transparent top which allows light in but stops humidity escaping. The simplest form of propagator would be a waterproof box with clear plastic sheeting over the top. The advantage of shop-bought propagators is that they often have built-in heating and/or vents in the cover to allow humidity regulation. They also usually allow more light to reach the seedlings.

Place your propagator next to a window to give the seedlings light, but avoid direct sunlight for the first couple of weeks.

When can seedlings be put under lights / in the sun?

When seedlings have grown their second or third set of serrated leaves (not counting the round cotyledons that initially emerge from the seed) they are usually hardy enough to flourish in direct sunlight or beneath a grow-lamp (preferably metal halide or fluorescent tubes). Always keep your grow-lights at least 50cm from your seedlings.

When can I tell whether they are male or female?

Cannabis will only show its sex once flowering has begun. Cannabis begins to flower when it receives 12 hours of light and 12 hours of uninterrupted darkness in each 24-hour cycle. Once this light cycle (or photoperiod) is initiated, the first flowers should be visible within 2 weeks.

Inside, it is the decision of the grower when to alter the photoperiod and induce flowering. This is achieved by simply adjusting the timers on your lights.

Outside, the grower must wait until the natural daylight hours have decreased to 12 per day. Exactly when this occurs will, of course, vary depending on your locality. In Northern Europe it happens around mid-to-late July.

It is possible to induce flowering outside by allowing your plants 12 hours of daylight each day, then covering them or taking them inside. This must, however, be done every day without fail.