Origin
Achnatherum lemmonii (Swallen) Barkworth var. lemmonii, commonly known as Lemmon's needlegrass, is a native perennial grass species that originated from North America. It is commonly found in California, Arizona, Nevada, and New Mexico in the United States.
Common Names
Lemmon's needlegrass is also known by several other common names such as Lemmon's oatgrass, slender oatgrass, and Lemmon's Stipa.
Uses
Achnatherum lemmonii is used for ecological restoration, soil stabilization, and erosion control. It is known to create soil structures that are ideal for the germination of other plant species, and its deep roots penetrate deep into the soil, increasing water infiltration and binding the soil together, thus reducing the chances of soil erosion. Additionally, it is an important forage grass for livestock.
General Appearance
The plant is a slender, erect bunchgrass that can grow up to 60 cm tall. Its leaves are yellow-green, long, and narrow, ranging from 1-3 mm wide. The inflorescence of the Achnatherum lemmonii is a dense and narrow spike-like node that contains small flowers. It has a characteristic silver or bronze hue that adds to its overall attractiveness. The seeds of the Achnatherum lemmonii are small and have awns that make them ideal for dispersal by wind currents.
Light Requirements
Achnatherum lemmonii requires full sun exposure to thrive. It can tolerate some shade, but it will not grow as vigorously or produce many flowers in low light conditions. Therefore, it is best to plant A. lemmonii in a location that receives direct sunlight for several hours every day.
Temperature Requirements
A. lemmonii is native to the western United States, where it grows in a variety of different climates. However, it prefers cool to moderate temperatures and does not do well in hot, arid conditions. The ideal temperature range for A. lemmonii is between 50 to 80 degrees Fahrenheit.
Soil Requirements
A. lemmonii grows best in well-draining, nutrient-rich soil. It can tolerate a wide range of soil types, from sandy to clayey, as long as it is not waterlogged. A. lemmonii is adapted to thrive in soils with a neutral to slightly acidic pH (6.0-7.5). If planting in heavy soil, add organic matter or sand to improve drainage and prevent the roots from becoming waterlogged.
Cultivation
Achnatherum lemmonii (Swallen) Barkworth var. lemmonii, also known as Lemmon's needlegrass, grows well in a variety of soils, including sandy, loamy, and clay soils. It prefers a well-drained soil and can tolerate drought, heat, and cold weather conditions. The ideal location for planting Lemmon's needlegrass is in an area with full sunlight exposure, but it can also grow in partially shaded areas.
Watering Needs
Lemmon's needlegrass is quite drought tolerant, and therefore requires minimal watering. It is a hardy plant that can withstand long periods of drought, especially once established. However, for optimal growth, it is recommended to water deeply but infrequently. Only water when the soil has completely dried out, and avoid overwatering as it may lead to root rot.
Fertilization
Achnatherum lemmonii requires minimal fertilization, as it is adapted to grow in nutrient-poor soils. In case the soil is nutrient-poor, a slow-release fertilizer can be added once a year during the growing season. However, it is important to ensure to avoid fertilizers that are high in nitrogen, as they may promote excessive leaf and stem growth, leading to decreased drought tolerance.
Pruning
Pruning is not necessary for Lemmon's needlegrass, as it is typically left in its natural form. However, it is important to remove any dead or damaged stems or foliage to keep the plant healthy and tidy. This can be done yearly, typically in early spring, before new growth begins.
Propagation Methods of Achnatherum lemmonii
Achnatherum lemmonii (Swallen) Barkworth var. lemmonii, commonly known as Lemmon's needlegrass, can be propagated through various methods such as seed propagation, division, and stem cuttings.
Seed Propagation
The most commonly used method for propagating Achnatherum lemmonii is through seeds. The seeds of the plant are easily available, and they can be sown directly into the ground where the plant is intended to grow. The ideal time for sowing seeds is in the fall when the soil is still warm from the summer sun. The seeds require light to germinate, so they must not be buried too deep in the soil. Once sown, the seeds take 2-4 weeks to germinate.
Division
Achnatherum lemmonii can also be propagated through division. This method involves removing a clump of the plant from the ground, dividing it into smaller sections, and planting them separately. Division is best done in spring or fall when the plant is not actively growing. The soil should be kept moist until the divisions become established.
Stem Cuttings
Propagation through stem cuttings involves taking a stem of the plant, cutting it into smaller sections, and planting them in soil or water. This method is not commonly used for Achnatherum lemmonii, but it can be useful for propagating smaller sections of the plant.
Disease Management
Achnatherum lemmonii var. lemmonii is generally a healthy and hardy plant with few disease problems. However, the plant can occasionally develop problems with some fungal and bacterial diseases.
Crown rot, caused by the fungus Fusarium spp., can cause the plant to wilt and eventually die. To manage crown rot, avoid planting in poorly drained soils and provide adequate water and nutrients to the plant.
Leaf spot, caused by the bacterial pathogen Pseudomonas syringae, can cause yellowing and browning of the leaves. To manage leaf spot, prune and remove infected plant parts and maintain good plant hygiene.
Pest Management
There are also a few pests that can affect Achnatherum lemmonii var. lemmonii. Here are a few common pests and management strategies:
Noctuid moths, such as the armyworm and cutworm, can feed on the foliage and stem of the plant, causing significant damage. To manage these pests, handpick them and use Bacillus thuringiensis (Bt) insecticide.
Grasshoppers, including the differential grasshopper, can also feed on the foliage of the plant and cause damage. To manage grasshoppers, use insecticides, such as pyrethrin, and install barriers to prevent them from damaging the plant.
Spider mites can be a problem in hot and dry conditions and can cause the plants' leaves to turn yellow and eventually fall off. To manage spider mites, wash the leaves with water or insecticidal soap, or use predatory mites or ladybugs to control them.
