Elephant Grass (Pennisetum purpureum or Napier Grass) is a towering perennial grass native to the tropical and subtropical regions of Africa. It is recognized for its rapid growth rate, reaching heights of up to 15 feet (4.5 meters) in a single growing season under optimal conditions. Due to its impressive biomass production, Elephant Grass is utilized across various sectors, including use as a highly productive forage crop for livestock, a source for bioenergy production, and an effective natural privacy screen in landscapes.
Establishing the Grass
Elephant Grass thrives best when given maximum exposure to sunlight, requiring a location that receives full sun for at least six hours daily. While the plant tolerates a wide range of soil types, including light sandy to heavy clay soils, it performs optimally in deep, fertile, and well-draining loams. The species shows tolerance for a broad soil pH range, from mildly acidic 5.0 to mildly alkaline 8.0.
The most reliable method for establishing the grass is through planting stem cuttings or rooted slips. Stem cuttings, ideally taken from mature stalks and containing at least three nodes, should be pushed into the soil at an angle with two nodes buried. Alternatively, cuttings can be laid horizontally in a furrow and covered with 1 to 2 inches of soil.
Proper spacing is determined by the intended use. For dense ornamental screens, cuttings can be placed as close as 18 to 24 inches apart in a staggered pattern. If the goal is a forage crop, wider rows spaced 3 to 6 feet apart are often used to allow machinery access and maximize individual plant yield.
After planting, the soil must be kept uniformly moist, but not waterlogged, until new shoots emerge and the root system begins to anchor the plant. Once established, the grass shows greater drought tolerance due to its deep root system. Consistent moisture during the first few weeks following planting is required to support root initiation and ensure a vigorous start.
Routine Maintenance During the Growing Season
Maintaining consistent soil moisture is necessary to achieve the plant’s maximum potential height and biomass. As a species native to high-rainfall areas, Elephant Grass responds to regular and deep watering, especially during prolonged dry spells when the top inch or two of soil becomes dry. Allowing the soil to dry out excessively will significantly slow growth.
Because Elephant Grass is such an aggressive grower, it is a heavy feeder that rapidly depletes soil nutrients, requiring a fertilization schedule to maintain high yields. To support the rapid production of leaves and stalks, a high-nitrogen fertilizer is typically applied at the beginning of the growing season and after each cutting. Applying a compound fertilizer with a high NPK ratio, such as 15-15-10 or 16-8-24, encourages substantial vegetative growth.
Successive applications of fertilizer should be made after each cutting or approximately every four to six weeks throughout the active growing period. This prevents nutrient deficiencies, which can manifest as yellowing or stunted leaves. The total amount of nitrogen applied over the season can be substantial, often requiring between 150 to 300 kilograms of Nitrogen per hectare annually.
Elephant Grass can occasionally encounter pest and disease issues. Fungal diseases like rust may appear as reddish-brown pustules on the leaves, usually during periods of high humidity. Spittlebugs are a common pest, often visible by the foamy substance they produce on the stems while feeding. Management involves cultural practices, such as ensuring good air circulation and avoiding overhead watering late in the day.
Managing Growth and Winter Dormancy
Managing Elephant Grass requires regular intervention. Periodic cutting, known as ratooning, encourages the production of new, tender shoots and prevents the stalks from becoming overly woody. For forage use, cutting the stalks down to a height of about 6 inches (15 cm) promotes rapid regrowth and maintains optimal nutritional value.
In regions that experience freezing temperatures or hard frosts, preparing this warm-season grass for winter dormancy ensures the survival of the root crown. Once the first heavy frost has caused the foliage to turn brown and dry, the stalks should be cut back severely, typically to within a few inches of the ground level. Cutting back the stalks prevents disease and simplifies insulation preparation.
The root crown requires protection from deep freezes by applying a thick layer of organic mulch, such as straw, shredded leaves, or wood chips. This layer, ideally 6 to 8 inches deep, helps regulate soil temperature and prevents the crown from freezing solid. The mulch should be pulled back slightly in the early spring to allow the soil to heat up. New shoots will emerge from the protected root crown once the danger of hard frost has passed and soil temperatures consistently rise.