a zygote. The polar nuclei unite with the second sperm cell nucleus, creating a primary endosperm. This endosperm divides into endosperm tissue, which becomes a source of nutrition. The source terminates shortly after the root and stem form. Gymnosperms have two sperm cells relocated from the pollen. Only one sperm fertilizes the egg. The seed is made up of the embryo and some tissue from the parent plant, which forms a covering around the seed. Seeds are formed in plant structures called fruits.
Another, more basic, definition of a seed is that it is a biological organism that is sown. However, seeds are not the only form of plant propagation. Ferns, for example, reproduce spores and an intermediate plant stage called a gametophyte.5 Seeds are the main reason why plants can successfully take over as much land as is available for sowing.
Cannabis Seed Structure
Seed shape and structure differ from plant to plant and will vary even within cannabis varieties. The cannabis plant embryo has two cotyledons (dicotyledons),6 also known as the seed leaf. The cotyledons take root by the radicle, which is the root in embryo—both of which are at either end of the plumule, the shoot that acts like an embryonic plant stem. The epicotyl is the embryonic stem above the site of attachment of the cotyledons, while below this site is the hypocotyl.
For seedlings or clones fluorescent lights are a good way to keep the internode lengths short so that the young plants don’t grow too tall.
In cannabis seeds, nutrition in the form of stored food starts with the endosperm containing oils, proteins, or starches produced in seed reproduction. The cannabis seed is albuminous, meaning that it is made up of simple, water-soluble proteins that can be coagulated by heat; an egg white is another example.7 The actual seed, though, is physically recognized by its outer layer, a tissue called the integument that covers the ovule. The cannabis integument is of the hard type.
Cannabis Seed Germination
There are two main initiators of cannabis seed germination. “Imbibing” is the process whereby the seed soaks up water, which eventually results in the seed coat splitting. Seed coat hardness is variable with cannabis seeds. Ripe seeds should germinate but immature seeds are often not viable (usually a soft whiteness of a cannabis seed is attributed to immaturity, although some strains have this natural density and color). The second initiator of germination is light, which can penetrate the shell of seeds that have a weak or permeable coat. If the coat is not permeable by light or water, the seed may not be viable at all. Other inhibitors may include bad soil, incorrect pH level, seed exposure, seed depth, weeds, rich nutrient content, physical damage from animal or environmental causes, and fungi. Germination can take 12 hours to several weeks, depending on the seed structure and germination conditions.
The seeds are a lot darker than many of the seeds we have shown so far. Seeds can have lots of variation.
A close-up of a seed out of soil that is nearing shedding its shell.
Cannabis Seed Functions
The inherent nutrient food substances in seeds allow the embryo to grow quickly. Cannabis seeds are heavy, meaning that wind travel is usually limited to a close area. Animals, birds, and man are the primary vehicles by which cannabis seeds are distributed over long distances.8 Cannabis produces resin along with seeds which means that when the opportunity presents itself, the seeds will stick to almost anything with which the resin come in contact. Cannabis seeds have a historical record of being edible, although for growers their value is not in being a source of food.
Dangers when Germinating Seeds
During germination and transplantation, your plants are at their most vulnerable. Here are some tips to help you protect your future crop during germination.
A close-up of a seed out of soil that has shed its shell.
A comparison of seedling with shell, without and after first leaves.
Drafts can stunt germination. Always make sure you keep your germinating seeds away from any open windows or fans. Also ensure that the room is warm. A cold room can inhibit your germination rates.9
Take care when using germination fertilizers or hormones to ensure that your mixture is correct. Do not use high doses of fertilizers with seedlings. Water is all seedlings really need. You do not need to add anything. Some people use germination solutions, but these solution strengths should be low. An incorrect mixture can burn your seedlings and cause them to fail.
Leave your seeds alone to grow.10 You may be tempted to check on your seedlings and could run the risk of disturbing the soil. This is a bad move as too much tampering and shifting of the seeds can break and damage the young roots.
Some strains produce seedlings with weaker stems than others. In these cases, the seedlings may tend to lean to the left or right. If you find that your seedlings need support then use a small stick to brace your seedling. Tie the stem to the stick using a piece of thread. Never tie the thread above a growing shoot or the seedling will push up against the thread and may rip itself. You may continue to use a stick to support your plant as it grows. Never bring a stick in from outdoors as bugs, like spider mites, may go undetected inside the wood. If your plant still has a weak stem during vegetative growth it is recommended that you give the base of the stem a gentle shake every morning and evening. This will help the plant to develop a more solid stem. Outdoors, the wind shakes the plant and causes it to develop more solidly. You can simulate the effect of wind by gently prodding the plant every morning for two or three seconds. Indoor fans also help and are described in more detail in Chapter 7.
Seeds must be viable if they are going to germinate. Never use white seeds. They are immature. Find seeds that have white and gray markings or another color apart from white. Crushed seeds will not germinate. Old seeds may have trouble germinating. Always try to use the best seeds you can find.
A collection of seedlings in pots. These can go either indoor or outdoor.
Transplanting Seedlings
During the stages between germination and vegetative growth the grower may find that plants outgrow their pots. Transplanting to bigger pots should be done as early as possible.
Here is an example. When your seedlings are ready, simply lift them from the propagation
