The flowering stage is where plants produce their fruits, vegetables, and flower sets. Learning to control the factors that cause a plant to flower allows you to produce flowers and fruits whenever you want, in spite of what season it may be outdoors. This technique is known as flower forcing.
Once you've figured out flower forcing, you are all set to move your plants into the flowering stage. Most plants will take about two weeks to fully adjust and respond to their new conditions. After that, you should have about a 10 or 14 day growth spurt. After a 10 or 14 day period of relaxed growth, you will get another 10 to 14 day growth spurt. Every plant will be a little different, of course.
Depending on the variety of plants you are growing, the nutrient solution strength should be kept somewhere between 700 and 1200 ppm. This is a very general guideline, and it is important to know the specific requirements of the plants you are growing! Many gardeners slightly increase the nutrient strength as the flowering period proceeds. If this is your first garden, make these increases very slowly and keep a close eye on your plants to determine their limits.
During the flowering period, plants put all their energy towards reproduction. Many plants have many different ways to reproduce. Mostly they all involve the production of seeds, either in flowers (i.e. sunflower), fruits (watermelon), vegetables (butternut squash), or as nuts (pistachios).
Shown here are the male (A) and female (B) parts of a tomato plant. Many plants have both male and female sexes....sometimes on the same plant, and sometimes as completely separate male and female individuals. Seeds remain infertile, or do not develop at all, unless pollinated by a male
plant (in most plants). Often the female plant will continue to produce more and more flowers in
an effort to reproduce, until fertilization happens. In fact, serious flower producers will identify and remove the male plants (when they are separate individuals) as quickly as possible, specifically to encourage female plants to grow enormous flower sets.
Once a flowering plant has received fertilization from male pollen over a significant portion (say 20-40%), new flower growth stops and the plant begins to focus it's full energy on the development of the seeds and fruits for the rest of the flowering stage. If only lightly pollinated, the plant may decide to continue growing new flowers while developing a few seeds. In other plants, seeds will develop during the flowering stage without the need for pollination or fertilization from a male plant at all.
Besides the dark period, temperature plays a significant role in flower/fruit development. A few colder-than-usual days near the end of the flowering stage could motivate the plant to finish things up a little quicker. Or, consistently keeping the nighttime temperature 10 to 15 degrees cooler than the daytime temperature makes the plant feel a little chilly every night, and it will grow shorter and stockier. Flower sets will tend to be more dense, and fruits and vegetables may increase their brix (sugar) content, making them sweeter and tastier.
Finally, if a flowering plant is approaching the end of its life cycle and still has not been pollinated, it might just pop out a few male flowers and go pollinate itself. This is called rhodelerization. It is a survival response, and not a genetic predisposition to produce male flowers on a female plant. Rhodelerized male flowers can be used to produce feminized seeds which will grow up and will not be predisposed to hermaphorditism.
A few other techniques exist for producing feminized seeds. For example, heat stress can cause a female plant to pop out a male flower. The problem is, you stressed a plant out and it identified itself as a plant that has hermaphoradidic tendencies (as evidenced by the fact that it just produced a male flower). Now, if you grow those seeds out, you are passing on that tendency for that variety of plant to pop out male flowers whenever it gets stressed out. When grown out, these flowers are pretty much guaranteed to produce seeds.
If male flowers had showed themselves on a female plant at some time before the late flowering stage, than it likely would have been from a genetic predisposition to do so. In this case, it is known as hermaphroditism. Hermaphrodites are, mostly, just aggravating and useless, You can make feminized seeds with the pollen, but all the resulting plants will be predisposed to hermaphorditism!
Returning to the seed stage completes the natural life cycle of plants and begins the next generation.