Cannabis seeds are growing on this lower pollinated female branch. The grower marks the seeded branch with a green plastic ribbon. (Courtesy of Jorge Cervantes via "The Cannabis Encyclopedia")

Why generating marijuana seeds at home from a clone is a complex endeavor

Cannabis Cultivation Q&A: What you need to know about hermaphrodite plants and making your own cannabis seeds

Renowned grower Jorge Cervantes will answer readers’ questions and give advice on all things related to the cannabis plant. Got a question for Jorge? Email him at jorge@marijuanagrowing.com.

Editor’s Note: Laws for cultivating cannabis vary from state to state and city to city — before germinating any seeds or planting any clones, take care to learn what your local laws are.

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Question: I want to produce marijuana seeds. Could it be possible to induce a male from a cloned female? How do you get the male? Thank you very much. — David

Answer: Production of marijuana seeds can take many forms. Fundamentally, natural cannabis seed production requires a male plant and a female plant. Pollen from a male flower lands on the stigma of a female flower and makes its way down to the ovule deep inside the seed bract, thereby fertilizing it. A seed starts to grow.

Seed production appears simple at first glance, but the science is extremely complex. Each plant has a set of 10 genes with dominant and recessive traits. The combinations of gene crosses, a.k.a. phenotypes, are virtually limitless.

A female clone can be induced to produce male flowers that contain viable pollen. This pollen will serve to self-fertilize female flowers on the same plant. The fertilized female flowers can then produce viable cannabis seeds.

This breeding process is called “selfing” because the plant breeds with itself. The pollen produced by the male flowers will create predominately (about 99 percent) female plants. These marijuana seeds are considered to be “feminized.”

The major pitfall to producing feminized marijuana seeds at home is the appearance of “intersex” plants — also called hermaphrodites. These self-pollinating (and seed-producing) plants are the result of unstable genes in a plant that is a mix of its own genetics. Any recessive genes can be duplicated outright or could manifest in future generations. The provability of recessive genes in future generations is very, very high. The progeny of marijuana seed from a hermaphrodite plant and subsequent offspring will naturally be weaker than if it had been bred with the outside gene pool.

Promoting male flowers on female plants can be achieved by inducing environmental stress or altering hormone levels with chemicals.

One could cause male flowers to grow on a female plant by letting it flower longer than normal; often a few male flowers will grow in the late flowering stage. An irregular light schedule (photoperiod) or low temperatures are types of environmental stress that can result in the growth of male flowers.

Plant hormone levels can be altered with colloidal silver (CS), silver thiosulfate, gibberellic acid (GA3) and ethylene. Use of these substances is complex and would take a couple of articles to explain. More information can be found in “The Cannabis Encyclopedia,” available at amazon.com.

To learn more about the realm of cannabis genetics, please take a look at the Phylos Bioscience website, which claims to have the world’s largest database of cannabis DNA. Researchers at Phylos Bioscience have decoded the genome (DNA) of about 2,000 different cannabis plants.
Click on “The Galaxy” for an interactive map of the many cannabis plant varieties cataloged by Phylos Bioscience and how they relate to one another.