If growing outside, some growers prefer to germinate seeds inside because they are delicate in the beginning stages of growth. Indoors, you can give weed seedlings supplemental light to help them along, and then transplant them outside when big enough.
But if the seed you found looks decent, you might as well germinate it and see what sprouts.
How weed seeds work
For the typical homegrower, it may be easier to obtain cannabis seeds rather than clones. Growing from seed can produce a stronger plant with more solid genetics.
Sexing marijuana plants can be a time-consuming process, and if you don’t catch males, there is a risk that even one males can pollinate your entire crop, causing all of your female weed plants to produce seeds.
In some cases, even if a seed isn’t completely mature, there’s still a chance it could be viable. But often these are extremely weak, take long to develop, and express other unfavorable characteristics. Growers usually discard weak plants to free up space.
Line the bottom of the first plate with a few layers of wet tissue and drain any excess water from the plate.
Within a few days some or all of the seeds should open and put out a root. It is common for cannabis seeds to open within 72 hours of being put in the germination medium. Less commonly, some seeds may need up to 10 days or even two weeks to open and put out a root.
Step 1. The setup – How to germinate cannabis seeds
Check the seeds every day to ensure that the tissue does not dry out. Spray the tissues with water if necessary.
Seedlings intended for outdoors should be acclimatised to direct sunlight by placing them on a windowsill inside the house and increasing their exposure to direct sunlight by an hour or two per day.
The best way to germinate cannabis seeds requires only two saucers or plates and some moist tissue. Here is a step by step guide.
1) Set seeds in a matchbox with an emery board or sandpaper on the bottom.
Some seeds have a very hard outer shell (testa) and are difficult to germinate. Such testy cases can be softened or scarified to allow water to penetrate. To scarify, line a matchbox with a piece of fine-grain sandpaper or emery board. Put the seeds in the matchbox and shake for 10 to 15 seconds. Remove the seeds and make sure they have been scuffed a bit. Just a little scuffing will allow water to enter and set germination in motion.
4) Place the seeds in a warm location (70°F–80°F; 21°C–27°C), making sure they are in darkness. Some gardeners go so far as to set the plate in a vertical position (so taproot grows downward). The seeds can also be set on a grate for drainage and air circulation.
Other Tips for Germinating Cannabis Seeds
3) Shake matchbox for 10 to 15 seconds to scarify the seeds.
When the growing medium’s surface is dry (0.25 inches [1 cm] deep), it is time to water. Remember, there are few roots to absorb the water early in life and they are very delicate.
A shallow flat or planter with a heat pad underneath may require daily watering, while a deep, 1-gallon (3.8 liter) pot will need watering every three days or more. A properly watered flat of rockwool cubes needs water every three to five days when sprouting seeds.