Separate or sift seeds over the screen to remove any unwanted plant matter from the seeds themselves. Brush off the seeds—they should be completely free of any remaining plant material such as leaves, stem, or trichomes, as these elements put seeds at a higher risk for contamination and spoilage during long-term storage.
When collecting seed by hand, use a fine screen to help catch trichomes that will break off during the process. This material is valuable and it would be a shame to waste.
How to Collect Seeds
Cannabis is for the most part dioecious, meaning that the male and female reproductive organs exist on two separate plants (although hermaphroditic plants do occur). It is also a wind-pollinated plant, so pollen must be transferred from a male stamen to a female pistil via the air in order for pollination to occur and seeds to form.
Male cannabis plants will produce pollen several weeks into their flowering cycle. Once their pollen sacs have opened up and released, the plant will begin to senesce and eventually die. It is important to collect pollen right as the sacs are beginning to open up, as this is the time pollen is most viable.
A grower or breeder can also freeze the progress of a breeding project for months or years without losing any of the long, hard work. Endeavors such as phenotype hunting and maintaining desired mothers for breeding and cloning can all be saved for later through genetic preservation. This process is like backing up work on a hard drive.
Sea Of Green (SOG) allows you to grow more plants per square metre. You switch to 12/12 lighting early, creating a ‘sea’ of flowering buds.
The transition from the growth to the flowering stage is marked by serious stretching. The cannabis plants soar up to the tent roof; some strains can triple their height at this point. Take this into account to make sure your plants fit your grow space.
Keeping Your First Cannabis Home Grow In Check
Once the seeds become seedlings, with roots showing on the sides and bottom of the grow plus (usually after about four days), they’re ready for planting. I start with small P9 size flower pots. I’ll leave them for 7 to 11 days to give the roots time to develop, creating a stable habitat.
LST, or low-stress training, simply amounts to bending and fixating your plants. This ensures maximum grow surface spread and enough light for optimal flowering across all branches.
After germination comes the vegetative or growth stage of the cannabis life cycle. In indoor conditions, the plants will keep on growing as long as they get 18 hours of light. This is a 16-8 lighting regime (18+6=24, i.e., a whole day). Autoflower strains are an exception; these switch from growth to flowering automatically.
If you meant when to harvest seeds from cross-pollinated Marijuana plants, then the seed will fall from the flower by itself once it is mature and ready to germinate into another Marijuana plant. Usually, as a best practice to harvest Marijuana seeds, some growers wait for the whole flowering cycle to end just as if they were harvesting the flower.
After the whole process of germination, growth and flowering, a lot of growers ask themselves when to harvest Marijuana seeds. Usually, the breeders will include a suggested flowering time for each strain, but as a rule of thumb, Indica marijuana plants harvest in 6-8 weeks while Sativa Marijuana plants take 10-12 weeks.
You can also judge the ripeness of the Marijuana by taking a look at the trichomes; or little hairs/crystals on the flowers and surrounding areas of the Marijuana plant. If they are transparent its still too soon, if they are milky white they are ready and if they turn brown they have become over-ripe. It is also advisable to follow the instructions to harvest Marijuana seeds on the packet since most reputable breeders also have a tried and tested flowering time for optimum ripeness, potency and flavour of a Marijuana strain.
Look for these signs for when to harvest Marijuana seeds
You might find our FAQ Submission How Do I Harvest My Plant? useful