Temperature — Soil temperature plays a major role in the growth of grass. When soil temperatures reach 50 degrees, grass will start to come out of dormancy and grow. Between 50 and 75 degrees, cool season grasses will grow most vigorously. Temperatures over 85 degrees will slow the growth of cool season grasses. Moisture — Adequate moisture is key to the growth of turf grass.
For that you need species that aggressively produce numerous stolons or rhizomes. For superior turf for heavy-duty use on sports fields, try our Promaster mixture. For late sowing we also recommend our Expressmaster mixture. Figure 1. Diagram of a mature grass plant.
A grass leaf is divided into three parts: the blade, sheath, and collar region Fig. The blade is long and narrow and grows more or less horizontally away from the main shoot. The sheath is the portion of the leaf that envelopes the shoot or stem. The collar region is located where the blade and sheath meet and may or may not have structures called the collar, ligule, and auricle Fig.
The smooth area on the back side of the leaf where the blade and sheath meet is the collar. It is usually a lighter color than the blade and may continue across the width of the leaf or be divided in half by a large mid vein. A ligule is a thin piece of tissue that extends just above the top of the leaf sheath and can vary in size and shape.
An auricle is another small piece of leaf tissue that grows from the collar and can also vary in size and shape. Figure 2. Diagram of a grass leaf, including blade, collar region, and sheath. Figure 3. The collar region of a grass leaf with ligule and auricle. Roots: Roots are the below-ground part of a grass plant that anchor it in the soil and take-up water and nutrients. Turfgrass roots are fibrous, branching, and very slender. There are two types of root systems in grasses, the primary and the secondary.
The difference between the two will be explained later in this section. Three types of stems occur in grasses; the crown, horizontal stems rhizomes and stolons , and the flower stem. Although the crown is a stem, it does not look like the other stem types found in grasses. It is very small just a fraction of an inch long , white, and completely enclosed by leaf sheaths.
The crown is located in a protected position between the roots and shoot near the soil surface. Horizontal stems begin to form in the crown and develop into rhizomes or stolons. Rhizomes grow below ground for a short distance, then rise to the soil surface to form new shoots.
In some grass species, rhizomes produce growing points often referred to as nodes which give rise to roots and shoots forming new or 'daughter' plants.
Rhizomes are usually white. Stolons grow above-ground and form nodes which give rise to new plants. Stolons are green and can creep over other grasses and bare spots in lawns, often forming circular patches. Flower stems are also formed in the crown, usually in late spring or early summer in most cool-season grasses. Typically, they are not seen in turf since they are mowed off before they reach maturity.
On unmowed grass, flower stems grow vertically and give rise to seed heads. The seed head is the flowering part of the grass plant. The basic unit of the seed head is called the spikelet. A spikelet is made up of grass flowers, the small stalks that support them, and bracts small, papery leaves that cover the flowers Fig.
There are three types of seed heads based on the arrangement of the spikelets; panicle, spike, and raceme Fig. In the panicle type, the spikelets are borne on branches that are arranged along the central or main stem. The main stem is basically an extension of the flower stem. Kentucky bluegrass is a turfgrass with a panicle-type seed head.
The spike-type seed head has spikelets that are borne directly on the main stem. Perennial ryegrass is a turfgrass with a spike-type seed head. In the raceme type, spikelets are borne on very short branches along a main stem. True raceme seed heads are rare in grasses and none of the cool-season turfgrasses produce them. Crabgrass, a common annual grass weed, has a modified spike-like raceme. Figure 4. A spikelet, the basic unit of the seed heads.
Figure 5. Three types of turfgrass seed heads; panicle, spike, and receme. The 'seed' of grass is really a dried fruit called a caryopsis Fig. The caryopsis is made-up mainly of the embryo and endosperm. The embryo contains the beginnings of the leaves, growing points, and roots of the grass plant. When left to their own devices, grasses will grow to their maximum height and then go to seed.
Their seeds typically grow at the tip of the plant. But some grasses have adapted to mowing. Their seeds form close to the ground, out of reach of the mower blades. Facebook Twitter.
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