Vascular System

• The vascular system transports water and nutrients from the root and up the stem or trunk of the plant to the upper portions, where these nourishing items can be best utilized. Plants that reach a tall height need a way where water and nutrients can reach the highest branches and leaves. This is accomplished through the vascular bundles (xylem and phloem), which also transport plant sugars to different parts of the plant.
  
  

Woody Stem

• Trees, shrubs and even a few annual plants all have a woody epidermis or skin that serves as protection and support for the living and growing plant. Not only do plants need the outer layer called bark, but they also need to be able to grow a trunk, which can support the living entity.
  
  

Water

• Plants in the desert do not grow very tall, while those that prefer the temperate and tropical rain forests can grow quite tall. This information points to the importance of water in the growth and survival of all forms of vegetation. Since water is a necessary ingredient for the process of photosynthesis, no plant is going to grow very tall or large without the vital liquid. In photosynthesis, water and carbon dioxide combine with the aid of sunlight to make the carbohydrates and starches that nourish the plant. If water becomes a limiting factor, then plant growth is usually limited.
  
  

Sunshine

• Without sunlight, a plant cannot live unless it is a mushroom and draws nourishment from decayed living matter. Plants need sunlight to fuel the photosynthesis process, which is so critical to their survival. Even during the growing process, plants are in constant competition with one another to reach a place of full sunlight, where they can absorb as much of the sun's rays as possible to keep growing taller. Plants that win this fight for available sunlight tend to grow fastest.
  
  

Conductive Substrate

• Soil conditions need to be present, where nutrients as well as water can be absorbed through the root system to feed the plant. Soils need to be of such a nature where there is an abundance of organic matter that can feed the plant. Also of importance is the depth and condition of the soil. A tree needs a strong and deep root system to grow tall; shallow or hard-packed soils do not meet these requirements.
  
  

Temperature

• Even though most conifers stay green all winter, the cold temperatures are not conducive for growth. There is a temperature range for maximum growth, which generally lies in the 50 degrees Fahrenheit to 80 degree range. Temperatures below that range tend to retard growth, while hotter temperatures can create an evaporation rate that is counter-productive to good growth.