The Basics

• Channels in plant stems carry chlorophyll, water and nutrients between roots and leaves.
  
  Plants need three things to live: sunlight, water and nutrients. Different types of plants require different amounts of light, water and soil compositions. Gardeners can locate plants where they get the right amount of light and irrigate areas that are too dry. They also may need to add fertilizers to give soil the nutrients required. Sunlight stimulates the production of chlorophyll, the compound that fuels the digestive system of plants and gives them their distinctive green color. Water circulates from the plants roots and pores in the leaves from top to bottom and back again, carrying chlorophyll down to process the nutrients from the soil and then back up to the plant's growing branches, leaves and inflorescences (flowers, fruits and seeds). When the plant finishes its growing and flowering, it sets seed and dies, returning nutrients to the soil that gave it life. In soil that is regularly cleared of vegetation or where non-native vegetation is forced to grow, like lawns and gardens, the soil must be enriched with chemical or organic matter that provides appropriate nutrients for the next generation of plants.
  
  

Macronutrients

• Compost provides complete macronutrients.
  
  Six "macronutrients" make up the bulk of the nutrients used by plants. Nitrogen is part of the chlorophyll that helps plants digest other nutrients. Plants "breathe" nitrogen from the air through their leaves. Nitrogen is especially available during thunderstorms when lightning converts it to a "fixed," or easily digestible state. Some plants, like soybeans and other legumes, also "fix" nitrogen in soil where it can be absorbed by other plants. Nitrogen aids growth, fruit and seed production. Phosphorous is used by plants for photosynthesis---the process that converts carbon dioxide into starches and sugars used to produce cellulose. Potassium is the second most important macronutrient. It helps form the proteins that fuel fruiting and reduce plants' susceptibility to disease. Phosphorous prompts new tissue growth at the top and bottom of plants and is essential for blooming plants and fruits. Three other macronutrients are important for plant growth and health. Calcium strengthens plant cell structure and filter out alkali salts and organic acids. Magnesium, essential to the process of photosynthesis, activates plant enzymes important to the growth of cells and tissues. Sulfur encourages enzyme and vitamin production and "hardens" the plant against cold.
  
  

Micronutrients

• Grass, stressed by frequent mowing and crowding, needs extra fertilization.
  
  Several minerals are necessary in smaller amounts for plant health. These "micronutrients" work in the metabolic system of the plant or in the process of photosynthesis to help digest or use other nutrients. Boron helps produce carbohydrates and sugars and zinc helps process them as does manganese that also aids in nitrogen metabolism. Molybdenum also facilitates nitrogen usage. Iron is a basic building block of chlorophyll. Chloride helps photosynthesis and copper is necessary for reproductive growth. Nickel and sodium are also required by certain plants. Each of these minerals must infiltrate the roots of the plant to enter its metabolic system.