Propagation and Breeding


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Lately, there seems to be a lot of interest from many members desiring propagation; to try their hand at making their own seeds. Spreading the love, how cool is that. I thought this might be helpful. Good hunting! mu

Excerpted from Mel Frank’s, “Marijuana Growers Guide” chapter on Propagation and Breeding:

Marijuana is naturally prolific. It has been estimated that a single male plant can produce over 500 million pollen grains. A large female plant can bear tens of thousand of seeds. In nature, pollen is carried from the male flowers to the stigmas of the female flowers by air currents or the wind. Indoors or out, if the plants are simply left on their own, most gardens produce many more seeds than are needed for the next crop.

Seeds usually become viable within two weeks after pollination, although they may have not developed good color by this time. The color can take several more weeks to develop, particularly indoors or late in the year when the light is not as strong. Once seeds are plump, well-formed and of a mature size, most of them will be viable. When seeds have also developed good color, their viability should be over 90 percent

Pollination may be carried out artificially. Pollen can be collected and then transferred to the female flowers with a cotton swab or artist’s brush, or shaken directly over the flowers. Store pollen in a clean, open container and keep in a dry area with moderate temperature. Remove any flowers or vegetative material from the pollen, because they encourage fungal attack.

One advantage of artificial pollination is that only the flowers of certain plants need to be pollinated. This allows you to harvest most of your grass as sensimella, while developing seed on part of the plant. If you only have a few plants, pollinate a single branch, or perhaps a few lower buds in order to leave the most potent buds seedless.

A good way to insure a good pollination and to avoid contaminating other females, is to loosely tie a transparent bag containing pollen directly over individual buds, branches or whole plants. Shake the bag to distribute the pollen and carefully remove it from several hours to a few days later.

To avoid contaminating a sensimella crop, you must remove any males from the garden before the flowers open. Males in pots can simply be moved to another area or room if you want to keep them growing. Male plants can complete development even in lower light; so they do not need artificial light. Otherwise the best procedure is to harvest the males intact by cutting them at their base after some flowers have formed distinct (but unopened) buds. Hang the whole plant upside down in a sheltered area where there is moderate light and where temperatures and humidity are not extreme. Place clean plates or sheer plastic beneath the plants to catch falling pollen. Generally there is enough stored water in the plant for the unopened flowers to mature and drop pollen. Well-formed flowers may open the next day. Usually all the flowers that are going to open will do so within two weeks.

Pollen gradually loses viability with time, but pollen that is three weeks old generally has sufficient viability for good seed production. However, the age of the pollen may influence the sex ratio of the next generation.

For instance, in a 1961 study with hemp plants, the percentage of females in the next generation was 20 percent higher than the control plants (natural pollination) when pollen is 14 to 17 days old was used. A small increase in female-to-male ratios also occurred when pollen was fresh (six hours or less). The age of the stigmas appeared not to affect the sex ratio.


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I have a copy of Marijuana Botany - An Advanced Study - The Propagation and Breeding of Distinctive Cannabis by Robert Connell Clarke. It is a must read (y)

You can find ebooks ;) but I do like a physical copy to relax in the chair with a nice fat spliff :)
Plenty more can be found either on or on both great sites for pdf files on many growbooks