What makes a plant grow?

The answer:

Carbon dioxide and water

To grow normally, a plant needs carbon dioxide, which it usually absorbs from the air through its leaves. It also needs water, which is usually absorbed by the roots and transported to the leaves and all other plant parts. Then, in the presence of the plant's green pigment (chlorophyll) and adequate warmth, the energy from the sunlight splits the water molecule to release hydrogen, which combines with carbon dioxide to form sugar. From sugar, the plant is able to make starch, other important carbohydrates, fats, proteins and other complex substances necessary for natural plant growth and reproduction. This process called photosynthesis, takes place largely in the leaves, but sometimes occurs in young green stems, green flower parts and even immature green fruits.

Mineral elements

Sixteen nutrients are essential for plants to grow and develop properly. A deficiency in any one may result in slow growth and unhealthy plants.

The 16 nutrients required by plants are based on the composition of plants by dry weight. The three nutrients that account for almost all the dry weight of plants - carbon, oxygen and hydrogen - are provided to plants by the air and water.

Of the other major nutrients, nitrogen, phosphorus and potassium are required in relatively large amounts and are the nutrients most likely to be deficient for plant growth. Secondary nutrients - calcium, magnesium and sulfur -are required in relatively large amounts, but are less likely to be deficient.

Micronutrients are essential to plants in relatively small amounts. They are iron, chlorine, manganese, boron, zinc, copper and molybdenum.

These elements are also referred to as minor or trace elements.

The major role that each nutrient plays in the growth of the plant is usually rather specific, and a deficiency of a particular element may result in characteristic symptoms.

Nitrogen is the nutrient most likely to be lacking in the soil, mainly because it is easily leached out of the soil by rain and irrigation water and because decay organisms feed on it. Under good fertile soil conditions, nitrogen fertilizer alone is sufficient for adequate growth, flowering and fruiting of trees, shrubs, woody vines and lawns.

Flowers, vegetables and indoor plants ordinarily require a fertilizer containing phosphorus and potassium as well as nitrogen.

For fruit and ornamental trees, shrubs, woody vines and lawns, apply only nitrogen unless a soil test has determined the need for other nutrients. Complete fertilizers are usually not needed annually except on flowers, vegetables and indoor plants.

Fertilizer

The term “fertilizer” means any material or mixture used to supply one or more of the essential plant nutrient elements.

Curt Peterson, Ph.D., is a professor of landscape horticulture and

nursery management on faculty at Florida Southern College. He resides in Union Springs during the

summer months. He can be reached at curt.peters@hotmail.com