Vetiver Grass 101: The Regenerative Super Plant
About Vetiver Grass
Vetiver grass (Chrysopogon zizanoides) is a sterile, non-running, clumping perennial grass known for its incredibly deep root system. In addition to its amazing erosion control and self-terracing capabilities, vetiver grass is utilized around the world for biological remediation and soil decontamination, sewage treatment, livestock cut forage, crafts, and essential oil making, amongst many other uses. Vetiver grass is native to India, and is incredibly productive in terms of biomass production – up to 45-60 tons per acre per annum in the tropics. Vetiver grass clumps can grow up to 2 feet in diameter and up to 6’ tall within their first growing season in Central CA, depending on water supply. It is very drought hardy once established, though supplemental irrigation is required to get it well established during its first growing season.
Applications of Vetiver Grass
1. Erosion Prevention And Repair
Vetiver grass is unique in its fantastic ability to completely halt sheet flow erosion. Because the clump is so dense, it creates a backstop behind which sediment can build up. Instead of this killing the plant, vetiver is capable of rooting into this new build up even when buried via nodes on mature stems. In this way, over time vetiver ‘self-terraces’ creating level contour paths of sediment held in place by its thick culms and dense, deep root system.
For erosion control on moderate-steep slopes, vetiver grass slips are typically planted on contour in a narrow trench (4-6” wide), approximately one every 4″. When planted at this spacing and provided with establishment irrigation, the vetiver slips will grow into a solid wall of culms that acts as a ‘biological retaining wall’ – a self-repairing structure that gets stronger and more effective as it gets older instead of vice versa. Once the planting trench is dug, it is underlain with burlap (mainstream methods suggest using aviary wire to hold back ground vermin until plants are establish, but this is non-biodegradable and good success has been observed using burlap for the same purpose) and then filled with compost or rotted steer manure (1 cubic foot of rotted manure fills ~ 6’ of trench). The high nitrogen compost or manure helps the young slips to grow rapidly and set their roots.
Below are images and videos from a pathway installation and slope stabilization project designed and installed by 7th Generation Design during the summer of 2017. Vetiver was planted on contour in rows separated by ~ 24″ vertically (actual distance between rows varied slightly due to terrain undulation). The slope was a fill slope (created during the leveling of the pad for the house) with very fragile, hydrophobic soils, and the grade ranged from between 55-65% (29-33 degrees). The edge of the slope had been steadily eroding due to wind and ground squirrel activity, leaving the homeowner with less yard each passing year. The vetiver was installed to halt this erosion process, provide some visual privacy from public walking paths below the house, anchor a gravity-glued stone pathway, and beautify the previously barren hillside.
Vetiver grass has countless examples of how it has been applied to stabilize and repair incredibly steep and damaged slopes. See the TVNI presentation on steep slope stabilization and rehabilitation for more examples.
2. Living Terrace Formation
Vetiver grass planted along contour at 4″ spacing will grow together to create a thick wall of stems, behind which sediment and organic material borne by water and wind will collect and build up. Vetiver culms root at nodes, and when a node gets buried or is put in contact with accumulated sediment, it will root into that sediment, stabilizing it and allowing the continued growth of the grass. In this way vetiver is self-terracing, and the terraces it creates will become broader and more level with time, unlike non-living terraces made with rock or masonry materials, which themselves will move with the shifting earth, eventually failing.
This amazing quality of vetiver grass is tremendously beneficial at jumpstarting revegetation and ultimately reforestation of barren, steep, eroded slopes where previously no organic material or seeds could be held long enough to take root and grow. Any vetiver line planted on contour, provided the slope is at a reasonably traversable angle, will create a level pathway across the slope’s face, which can be used to access parts of steep slopes that previously were too difficult to reach to utilize in a productive manner.
If you live some place that is steep and sunny, consider employing the self-terracing nature of vetiver as one potential way to create more usable and accessible land.
3. Livestock Cut Forage And Bedding
Vetiver grass is a nutrient and mineral rich livestock feed for horses, cattle, sheep, goats. It makes an excellent bedding for pigs and other livestock systems. Vetiver grass can be ensilaged to make hay. It can also be grazed free-range. In areas where free-range grazing is not possible, vetiver makes a tremendously productive and completely renewable source of high-quality cut forage that can be brought to penned animals.
Vetiver grass makes an excellent forage given its high yield, nutritional density, tolerance of extremely adverse conditions (drought, flood, fire etc), high adaptability to different soil types (clay, hardpan, sand etc), tolerance for a broad range of growing conditions (extreme pH, alkalinity, salinity, sodicity), tolerance to most agricultural insecticides and herbicides, and most pests and diseases. See the TVNI presentation on Vetiver Forage and Biomass for more examples.
4. Essential Oil And Crafts
The roots are used to make a high value essential oil, and can be woven into mats, bags, and screens used for filtering water. They can even be made into shoes! The blades of grass, when dried, are woven into screens and floor mats. See the TVNI presentation documenting the use of vetiver roots and shoots for crafting around the world.
Vetiver is useful in reclaiming toxic or damaged landscapes, and is capable of binding heavy metals and other persistent pollutants. These pollutants and heavy metals are retained in its root mass, leaving the shoot mass contaminant free and usable as fresh or dry feed for livestock.
Vetiver can be cut several times a year after the first year, using a simple rice knife. The grass can be lain in thick bundles around the bases of newly planted trees to provide an excellent evaporation-blocking, mineral-rich mulch, or it can be used as a non-woody bulk carbon input for thermophilic compost piles or Johnson-Su BioReactors.
The grass can also be let to grow. It will eventually reach a maximum height based on the growing conditions (just over 6′ tall in Coastal Southern CA). If you wish to keep vetiver grass green throughout Central and Southern California summers, some supplemental irrigation is recommended (though very little is needed). The plants will go dormant and turn brown during drought if not irrigated. Dead stems and blades of grass can be left to stand through the winter rainy season, an excellent form of bio-impedance to intercept raindrops before they impact bare or exposed soil.
Once temperatures warm enough for the vetiver to resume actively growing, the dead material should be cut and used as mulch or utilized in some other fashion. During the late fall and throughout the winter, the grass will take on a burgundy hue (if kept green throughout the summer), and send up bright green new blades upon resumption of growing conditions in the spring.
Vetiver grass is capable of growing in both very acidic (pH = 3.0) and very alkaline conditions, and can thrive in a wide range of soil types, from dense clay to steep volcanic hillsides to sandy and sodic soils. It is highly salt tolerant, and can be grown in brackish water, on beaches to help stabilize sand dunes, and as part of a biological wetland system for purifying human or livestock effluent. It can be burned to the ground and it will regenerate from the roots. Once established for a full growing season, vetiver grass clumps are effectively drought and frost hardy due to their deep root system (which can grow up to 9-15’ deep depending on the soil type), and can withstand temperature as low as 10 oF provided the ground doesn’t freeze too deeply.
In drier climates with cold, wet winters, vetiver slips should be planted immediately after spring rains cease and the danger of heavy frost has passed. Establishment irrigation is recommended during the first dry season to help the slips grow vigorously and set deep roots. Each line of vetiver should have its own designated ¼” drip line with emitters spaced every 6”. These can be effectively run up to 50’ lengths if supplied from both ends. Each line can have its own ¼” valves to make seasonal shut off very simple.
Vetiver grass is relatively simple to propagate if you wish to grow your own supply. See the detailed step-by-step vetiver propagation guide provided by TVNI for details.
If you are in central or southern California and are looking for a vetiver grass source we recommend Doug Richardson’s Drylands Farming Company, based in Santa Barbara, CA.