The Kentucky bluegrass originated in the northern parts of Asia and Europe, and in the mountainous regions of Morocco and Algeria. It was brought to the US along with different seeds carried by colonists. This 18-24 inch tall grass spreads by means of tillers and rhizomes. It can be easily recognized by its peculiar boat-shaped leaves. The grass completes its life cycle by producing an inflorescence as the seeds mature. A distinct characteristic is that its leaves are upright during the spring and summer season. The same leaves become decumbent at the end of summer. It happens due to the change in the length of the day.
Appearance and Growth
- The grass remains green in color for about 10-12 days when in the growing phase. Unlike the Bermuda grass which bears 5-7 green leaves per shoot, the Kentucky bluegrass has 3-4 green leaves on every shoot.
- The leaf blade reduces in length from the original 3-4 inch size, during the period between early spring and late summer.
- Shoots of some of these plants turn into rhizomes as they enter and grow beneath the soil.
- The branching of the rhizomes may continue for many years.
- During the fall season, a large amount of carbohydrates get accumulated in the rhizomes. These accumulated carbohydrates help in the growth of shoots during the next spring season.
- The growth of roots slows down with the increase in temperature; 60°F is the best temperature for the growth of roots.
Propagation and Management
- Generally, at the time of plantation, seeds of different varieties are mixed together, which result in better yield. Since different varieties have different qualities such as tolerance to temperature, shade, and harsh weather, mixed sowing reduces the risk of losing the entire lawn, which could happen if a single variety is used.
- The Kentucky bluegrass is propagated through sowing. A quantity of 2-3 pounds of seeds have to be used for an area of 1000 square feet. Seeds are sown by the method of 'broadcasting', i.e., spreading manually. The new growth of grass requires enough light and water - about 2-3 times in a day, at least for the first two weeks.
- Rotatory mowers are used for mowing, which is started when the grass reaches a height of 2 inches.
- To maintain it in the summer season, 2 inches of water has to be provided per week. Here, the quantity of water that covers the total lawn area is multiplied by the height; for example: 2 inches of grass is equal to 2 inches of water. However, the grass is tolerant to water stress, and it can survive without irrigation for a considerable period of time.
- It needs 5-6 pounds of nitrogen in the first year, while the requirement reduces subsequently, and 2-3 pounds of nitrogen is enough to fertilize it thereafter.
- Growing it in alkaline soil results in a deficiency, known as 'iron chlorosis'. The veins of the leaves turn yellow due to this deficiency. Since phosphorus fertilization worsens the problem further, it should be applied in minimum quantity.
Pest and Disease Management
- Dandelion, clover, and crabgrass adversely affect Kentucky bluegrass the most. These can be controlled with the application of 'pre-emergence' herbicides. These 'hormone-type' herbicides are used in managing the weeds with broad leaves.
- Trichlorfon (Dylox) can be used to control grubs.
- A common disease that affects it is Helminthosporium which develops leaf spots, powdery mildew, fusarium, and rust. Sowing seeds of disease-tolerant varieties is the best means to prevent this disease.
- Fusarium blight, a disease which causes rotting of roots and bleaching of leaves, can be managed by planting the bluegrass along with rye grass in a mixture.
Kentucky bluegrass looks beautiful in lawns and is also used in pastures. It is fed to horses, sheep, and cattle. It originated in Europe, and today it has covered a vast area in Canada and the USA. It is easy to harvest, and it grows in numerous varieties. This multipurpose grass is definitely a nature's gift to man.