Overview:
Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata is a flowering plant that belongs to the Brassicaceae or Mustard family. It is also known by other common names like Smooth Rock-cress, Smooth Rockcress, and Smooth Rockcress Mustard.
Origin:
The plant is indigenous to North America, and it is commonly found growing on rocky slopes, ledges, and crevices in the eastern United States. It is particularly prominent in states like Massachusetts, New Hampshire, Maine, and Vermont.
Appearance:
The Smooth Rock-cress can grow up to 30 cm tall, and its stems are branching, slender, and hairless. Its leaves are alternate, simple, entire, and oblong to linear in shape. The leaves are also glossy, with a dark green color and no hairs on the surface. The flowers of the Smooth Rock-cress are small, with four white petals arranged in a cross shape. The plants bloom in the spring, and the fruits are oblong capsules that contain many tiny seeds.
Uses:
Traditionally, Native Americans used the plant to treat various ailments like stomachache, fever, and wounds. The plant also has some culinary uses, and it can be eaten raw or cooked. Nowadays, the plant is primarily used for ornamental purposes, especially in rock gardens or as a ground cover plant. It is also used in ecological restoration projects to stabilize rocky soils and prevent soil erosion.
Light Requirements
Arabis laevigata var. laevigata requires full sunlight to grow. It is not tolerant of shade and requires at least six hours of direct sunlight per day to thrive.
Temperature Requirements
This plant is native to North America and can tolerate a wide range of temperatures. It is most commonly found in USDA hardiness zones 3-8, which equates to an average minimum temperature range of -40 to 20 °F (-40 to -6.7 °C). However, Arabis laevigata var. laevigata can withstand temperatures as high as 90 °F (32.2 °C) as well.
Soil Requirements
Arabis laevigata var. laevigata prefers well-draining soil that is neutral to slightly acidic. It can grow in a range of soil textures, including loamy, sandy, and clay soils. The plant is also tolerant of poor soil conditions and can grow in rocky or gravelly soils. It is not particularly drought-tolerant, so regular watering is necessary, especially during dry spells.
Cultivation Methods:
Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata is best grown in well-drained, loamy soil, which is slightly acidic. The plant should be grown in full sun, though it can also tolerate partial shade. It's best to sow the seeds indoors in the late winter or early spring, and then transplant them outside once they have sprouted and grown to a reasonable size. The plant is also tolerant of drought, so it doesn't need to be watered frequently.
Watering Needs:
The plant is drought-tolerant and can adapt to different water conditions. However, it does need to be watered during the early stages of growth, and during periods of extended dryness. Over-watering the plant can lead to root rot and damage, so it's important to strike the right balance when watering Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata. It's best to water the plant deeply, allowing the water to penetrate the soil to a depth of several inches.
Fertilization:
Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata doesn't require much fertilization and can thrive in low-nutrient soil. However, adding some compost or organic matter to the soil will help support the growth of the plant and provide the necessary nutrients. You can also add a balanced fertilizer to the soil every few months, but be careful not to over-fertilize the plant. Too much fertilizer can cause the plant to grow too quickly, which can lead to weak stems and a decrease in overall plant health.
Pruning:
To encourage healthy growth and bushiness, it's a good idea to pinch back the tips of Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata to promote branching. Deadheading the plant after it has finished blooming can also help encourage continued growth and promote the development of new blooms. Occasionally pruning out stems that are damaged or diseased will help keep the plant healthy and prevent the spread of disease.
Propagation of Arabis laevigata var. laevigata
Arabis laevigata var. laevigata, commonly known as smooth rockcress, can be propagated through different methods, including seeds, cuttings, and division.
Seed Propagation
Seeds can be collected from the plants in late spring and early summer, and can be sown immediately or stored in a cool, dry place until ready to be used. The seeds can be sown directly outdoors, or indoors in trays, pots, or a seed bed. Sow the seeds on the surface of the soil and cover them lightly with a thin layer of soil. Keep the soil moist and place the containers in a well-lit area. The seeds will germinate in 2-3 weeks.
Cutting Propagation
Cuttings can be taken from the plant during the growing season. Select a healthy stem, about 10 cm long, and remove the lower leaves. Dip the cut end in rooting hormone and plant it in a pot with a well-draining soil mix. Cover the pot with a plastic bag to maintain humidity and place it in a bright, warm location. When the cutting produces new leaves, it can be transplanted into a larger pot or directly in the ground.
Division Propagation
Division is another way to propagate Arabis laevigata var. laevigata. This method is best done in the spring, when the plant is actively growing. Carefully dig out the plant and gently separate the clumps into smaller sections, each with roots attached. Replant the divisions in a prepared bed or pot with well-draining soil mix and keep them moist until they establish roots and begin to grow.
Disease Management
Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata is prone to various types of diseases, which can affect its growth and yield. Here are some of the common diseases affecting the plant and ways to manage them.
Black rot
Black rot is a fungal disease that causes blackened lesions on the stem. The lesions decrease the plant's ability to uptake water and nutrients, leading to wilting and death. To manage black rot, prune off the infected area, and spray the plant with a fungicide. Be sure to observe proper sanitation practices, such as sterilizing pruning tools, to prevent the spread of the disease.
Downy Mildew
Downy mildew is a fungal disease that causes yellow blotches on the plant's leaves and results in stunted growth. It thrives in moist conditions. To manage downy mildew, remove affected plant parts and get rid of them. Increase air circulation by spacing out the plants to reduce moisture. Use a copper fungicide as a preventive or curative measure.
Pest Management
Arabis laevigata (Muhl. ex Willd.) Poir. var. laevigata is also susceptible to pests that can damage the plant's growth and yield. These are some of the common pests and ways to manage them
Aphids
Aphids are insects that feed on the plant's sap, causing it to wilt and die. To manage aphids, spray the plant with neem oil, which acts as an insecticide, fungicide, and miticide. You can also introduce beneficial insects, such as ladybugs, which feed on aphids.
Root maggots
Root maggots are small, white-colored larvae that feed on the plant's roots, causing stunted growth and wilting. To manage root maggots, use a nematode or a biological insecticide-based on Bacillus thuringiensis var. tenebrionis (Btt). Increase the soil's fertility and drainage to promote strong root growth. Practice crop rotation annually.
