in case you didn't feel like going to another thread reprinted here:
Growth Cycle
Marijuana is an annual plant, which is also called a single season (four to nine months) plant. The growth cycle consists of germination, seedling, vegetative growth, pre-flowering, flowering (also called blooming or fruiting), and finally seed set.
Let's look at each in a little more detail.
Germination - In nature, seeds naturally germinate during the spring thaw. Temperatures rise, ice melts, and the little seed absorbs water warmed by sunshine, which is absorbed by the embryo in the seed. This absorption causes the embryo to swell cracking the seed along the edge allowing the embryonic root or taproot to begin downward growth.
After the taproot gains a foothold, the germinated seed starts growing a stem upwards. The small, ovular embryonic leaves are called cotyledons. Often the cracked seed husk gets stuck on these cotyledons. This is normal and harmless unless, for some reason, the seed husk stops or impedes upward growth.
Seedling - once the second pair of leaves appears, the seedling stage begins. These leaves are very different from the cotyledons. They are bigger and have serrated edges. Another words, they look more like the marijuana leaves that are immediately recognizable. The plant will continue to produce more and larger leaves.
The seedling stage is at an end when the plant has reached the maximum number of leaves per blade. Usually nine to eleven leaves in four to six weeks.
Vegetative Growth - This phase is the plants maximum period of growth. The large fan leaves act as solar collectors, which allows for new and increased growth. The larger the plant is, the larger is its capacity for growth. Under perfect conditions, marijuana can grow six inches per day! The growth rate is normally closer to one to two inches.
About the middle of the vegetative growth phase, the number of blades per leaf begins to decrease. The leaves growing off the stem change from growing opposite to one another to growing alternate one another. Also the space between internodes, that is the space between sets of leaves on the stem, which was increasing begins to decrease and overall growth gets thicker. In the wild, the vegetative stage usually ends into the third to fifth month of growth.
Pre-flowering - After the plant completes its vegetative growth, it enters a "slow-down" period. This plant begins to switch from green growth to producing seeds (female) or pollen (male). This is when the first signs of sex can appear.
Flowering - As we learned earlier, Cannabis is dioecious. This means the plants are either male or female. A single plant can also have both male and female flowers and is called a hermaphrodite - but we'll learn more about that condition later.
During flowering, males start to develop their flowers that will soon fill with pollen. Because pollen is necessary for seeds, the male plant usually (but not always) begins flowering first. Male flowers are easily recognized as they are pale green or red/purple in color and look like little balls. Once the balls fill with pollen and the pollen is released, the male plants die.
Female flowers (or buds) have two small, fuzzy white hairs coming out of modified leaves called bracts and bracteoles. These modified leaves enclose the developing seed and form into dense groupings called buds. The most noticeable difference between early male and female flowers is males lack the two fuzzy white hairs called stigmas.
These flowers continue to bloom and grow until fertilized with pollen. After fertilization, seeds begin to form and grow. Flowering usually lasts two months but that depends a lot on the genetic strain and growing conditions.
Seed Set - is the final stage and is only reached by pollinated females. The male plants have already withered and died. Female plants that have been pollinated, produce more and more seeds that take from ten days to five weeks to develop and mature. Once seeds are finished being produced, the plant dies and drops its seeds.
Female plants that have not been pollinated grow big resinous buds without seeds called sinsemilla. Sinsemilla means "without seeds" in Spanish.