Turf Grass Growth 101

Your turf starts to grow either from seeds or from sprigs, sod or plugs—otherwise known as vegetative plant parts. Once established, turf grass management becomes vital to your lawn’s ability to reproduce, survive and thrive, so you’ll want to brush up on cultural practices.

And because all major types of turf grass that you would want growing in your lawn are perennial plants (meaning they can live for years and years), you should never lose sight of the long-term goals for your lawn.

The four major factors that determine turf grass growth are sunlight, moisture, carbon dioxide and soil temperature. Other growth influencers include the:

• Amount of nutrients available in your soil
• Kind of soil in your yard and its pH level
• Presence of beneficial organisms versus lawn pests
• Number of weeds present
• Slope and exposure of your yard
• Use of proper mowing and watering techniques
• Ways you use your lawn—e.g., high foot traffic, sports, recreation, etc.

The four major parts of an uncut, mature grass plant are:

• Leaves. There are three segments of turf grass leaves: blade, collar and sheath.
• Roots. Roots not only absorb nutrients and water from the soil, but they also anchor the soil to help fight erosion. The extensive fibrous root system of a turf grass plant renew yearly.
• Stems. Grass can possess three different types of stems: crown, flower stalk and horizontal stems (rhizomes and stolons).
• Seed head. The flowering part of the grass plant that produces seeds. Some seed head types include the spike and panicle.

Starting underground with the grass roots, nutrients and water are absorbed by the tiny root hairs that protrude into the soil. The roots then transport this life-sustaining nutrition to the shoots and leaves. At the tip of the root is the meristem, which is where grass grows.

As for leaves, they produce all of the food that your turf grass needs for development and growth. New leaves are produced at a point located at the base of the plant called the crown. The crown is tiny, white and totally protected by sheaths. If you set your lawn mower blades too low and damage the crown, new leaf growth becomes difficult to impossible.

The crown also plays a big role in the growth of stems—it’s arguably the most important material in any stem even if it doesn’t look like a stem. The crown produces new leaves, stems, rhizomes and/or stolons, plus it forms secondary roots from which new sod generates a new root system. Rhizomes and stolons also grow from nodes in the crown and spread out laterally.

• Bunch-type grasses. These spread primarily or entirely by the production of tillers but have trouble filling in bare spots. Common bunch-type grasses are Perennial Ryegrass, Tall Fescue, Hard Fescue and Chewings Fescue.
   
• Stoloniferous grasses. These spread by lateral stems called stolons that creep over the top of the ground. Stolons root at nodes and give rise to new shoots along the length of the stolon. Stoloniferous grasses fill in bare spots very easily. Common stoloniferous grasses are Buffalograss, Centipedegrass, St. Augustinegrass and Creeping Bentgrass.
   
• Rhizomatous grasses. These are much like stoloniferous grasses. However, these grasses produce below-ground stems known as rhizomes. Rhizomes give rise to a new plant some distance from the mother plant. These grasses are also very good at filling in bare areas. Common rhizomatous grasses are Kentucky Bluegrass, Bahiagrass and Red Fescue.
   
• Combination growth habit. These grasses include Bermudagrass, Seashore Paspalum and Zoysiagrass, which spread by stolons and rhizomes. These are very aggressive turf grasses that quickly fill in bare spots.

Photosynthesis governs turf grass growth. This is the process plants use to convert sunlight into the energy (carbohydrates) needed for growth and maintenance.

Photosynthesis simplified:

carbon dioxide + water + sunlight = sugars and starches + oxygen

Plants absorb carbon dioxide from the air, pull water up through their roots, and use light to make sugars and starches (carbohydrates). Plants then use the sugars and starches to grow and, in turn, give off oxygen as a byproduct.

The main function of a grass plant is to use sunshine to make food or carbohydrates. When the leaves produce more carbohydrates than are needed for growth and reproduction, excess carbohydrates are stored in the plant for later use. Turf grass plants store carbohydrates in the crown, roots, rhizomes and stolons.

When production is insufficient to meet the demands of the plant, the stored carbohydrates are used for continued growth. Carbohydrates are used for:

• Plant growth and maintenance
• Regrowth after mowing
• Seed head production
• Protection from stresses such as damage from insects, diseases and drought
• Survival during dormancy