The cannabis plant once it has been put into soil will spend energy growing tall and this means there is photosynthesis occurring. They will begin to grow tips at each pair of leaves the plant has and this is known by marijuana growers as vegetative growth. The tips that begin growing will be located at the top of the plant and at the internodes, and these are tips that can be used for clones by growers with a mother plant that rather than seed want to begin their crop with clones.

Every strain of cannabis has a vegetative growth period when they will spend all of their energy growing, and for this reason it is possible for the grower to have a crop that will have no dark period. This will increase the growing rate of the cannabis plants and then it will be up to the grower when to force the plants to flower, which can be at any height.  
One of the things the grower will need to do when growing a crop without darkness, this is to bend the stems or use a fan on the plants to make the stems grow strong, otherwise the grower will run the risk of having spindly stems that will not be able to hold the weight of the buds. The thin stems will be a risk for the grower, because it can break under the weight of the buds and the leaves of the growing cannabis plant, especially in plants that are reaching several feet tall.

When the marijuana plant is in the vegetation stage there will be the need to fertilize the plant and this can be done with a 20-20-20 fertilizer in soil and in hydroponics growing when the lights are one 24 hours a day. There are some fertilizers that are good for this type of growing that is made such as Rapid Grow or Miracle Grow Patio.
The fertilizer should be changed when going to 12 hours of light for flowering, to a mix like Peters 5-50-17 that is made for plants with blooms and fruit. The grower will also need to make certain that the type of fertilizer that they choose has trace minerals, magnesium and sulfur, because to have healthy marijuana plants that will have a quality harvest it is important they have all the nutrients they need.