Origin
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins, commonly referred to as the "denseflower rockcress" or "sparsely-flowered rockcress," is a species of flowering plant that belongs to the mustard family, Brassicaceae. It originates from western North America, specifically in the Pacific Northwest region of the United States in Alaska, California, Idaho, Montana, Nevada, Oregon, Washington, and Wyoming.
Common Names
Arabis sparsiflora Nutt. var. atrorubens is commonly known as the "denseflower rockcress" or "sparsely-flowered rockcress." Other names for the plant include "western rockcress," "redstem rockcress," and "purple rockcress."
Uses
Arabis sparsiflora Nutt. var. atrorubens is commonly used in horticulture as a groundcover or border plant, particularly in rock gardens. Its delicate pink-purple flowers, which bloom in early spring, make it a beautiful addition to any garden. The plant is also used for erosion control due to its ability to thrive in poor soil conditions.
General Appearance
Arabis sparsiflora Nutt. var. atrorubens is a low-growing perennial plant that typically reaches a height of 5-15 cm. It has a compact, mat-forming growth habit and produces spreading branches that are covered with small, slightly hairy, blue-green leaves. The flowers of the plant, which appear in clusters at the end of the stems, are a pinkish-purple color and have four petals that measure 4-5 mm in length. The plant blooms in early spring, usually from March to May, depending on the location. The roots of the plant form a shallow taproot system, which enables it to survive in rocky or gravelly soils that are well-draining.
Light Requirements
Arabis sparsiflora Nutt. var. atrorubens thrives in partial shade to full sunlight. It can grow under full sun exposure but may need more water to avoid heat stress. On the other hand, too much shade may hinder its flowering process. Ideal light exposure for this plant is around 4-6 hours of direct sunlight a day.
Temperature Requirements
This plant species prefers cooler growing conditions, with an ideal temperature range of 50-75°F (10-24°C). It is known to tolerate extreme winter temperatures as low as -30°F (-34°C) and summer temperatures of up to 90°F (32°C), but it may require extra care during extreme weather conditions.
Soil Requirements
Arabis sparsiflora Nutt. var. atrorubens prefers well-draining, slightly acidic to neutral soil with a pH between 5.5-7.5. It can tolerate dry soil, but the soil must be well-drained to prevent root rot. Slightly sandy soil is preferred, as it retains moisture well while also allowing for proper drainage.
Cultivation and care of Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins, also known as the purple rockcress, is a herbaceous perennial plant that is native to western North America. It produces erect stems that bloom with purple flowers in the spring.
Cultivation
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins grows best in full sun to partial shade. It prefers well-drained soil that is slightly acidic. Before planting, prepare the soil by adding compost or other organic matter to improve the soil's structure and fertility. Plant the purple rockcress in the fall or early spring.
Watering needs
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins is drought-tolerant and does not require frequent watering once established. Water the plant deeply when the soil is dry to the touch, but do not overwater, or the roots may rot.
Fertilization
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins may benefit from a light application of a balanced fertilizer in the early spring when new growth appears. Use a slow-release fertilizer at half the recommended strength. Avoid overfertilizing, as this can cause the plant to produce excessive foliage at the expense of flowers.
Pruning
Pruning Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins is not necessary. However, you can deadhead the plant after flowering to encourage reblooming and maintain a tidy appearance. Cut back the plant by one-third in the fall to promote bushier growth and improve its overall appearance.
Propagation of Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins can be propagated through several methods such as seeds, division, cuttings, and layering.
Propagation by Seeds
The easiest method to propagate Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins is by seed. Collect the seeds from the dried seedpods in late summer or early fall. After collecting the seeds, clean them properly and store in a cool and dry place until the time of sowing. Sow the seeds indoors in the early spring or sow them directly in the ground in the fall by digging shallow trenches and scattering the seeds thinly. Cover the seeds with a thin layer of soil and keep them moist until they germinate. Germination of Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins can take from 14 to 28 days.
Propagation by Division
Division is another method to propagate Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins, which involves dividing clumps of mature plants into several new plants. This method is best done during the early spring before the new growth emerges. Dig up the plants carefully and shake off the excess soil. Use a sharp knife or a spade to divide the clumps into smaller sections, making sure that each section has a healthy root system. Replant the new sections in a well-prepared bed with good drainage and water them well.
Propagation by Cuttings
Cuttings are also a viable method of propagating Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins. Take stem cuttings from healthy plants during the early summer or late fall. Cut about 4-6 inches of stem bearing some leaves, and remove any leaves from the bottom half of the stem. Dip the cut end in rooting hormone powder and plant in a well-draining soil mix. Water and cover with a clear plastic bag to maintain moisture and humidity. Place the cuttings in a bright, but indirect light, and watch for new growth in about 4-6 weeks.
Propagation by Layering
Propagation by layering involves bending a low-growing stem of Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins to the ground and burying a section of it while still attached to the parent plant. Make a small wound on the buried part of the stem to enhance rooting, and cover the area with soil. Water the buried stem regularly to keep it moist, and wait for new roots and shoots to emerge, usually within a few months. Once the new plant becomes established, carefully cut it off the parent plant and transplant it to a new location.
Disease Management
Arabis sparsiflora Nutt. var. atrorubens (Suksdorf ex Greene) Rollins is generally a healthy plant, but like all plants, it is susceptible to certain diseases. These include:
Fungal diseases
Black spot, downy mildew, leaf spots, and powdery mildew are fungal diseases that can affect Arabis sparsiflora. Fungi thrive in warm and humid conditions, so it is best to water the plants early in the morning to allow the leaves to dry out before the sun goes down. In cases of fungal infection, remove the infected parts of the plant, dispose of them properly, and treat the remaining plant with a fungicide.
Bacterial diseases
Bacterial diseases such as bacterial stem canker and leaf spot can also affect Arabis sparsiflora. These diseases can cause wilting, yellowing, and decay of the plant. The best way to manage bacterial infections is by promptly removing the affected plant parts and using a copper-based bactericide treatment.
Viral diseases
Arabis sparsiflora is also susceptible to viral infections such as cucumber mosaic virus. These diseases can cause stunted growth and distortion of the leaves. Unfortunately, there is no cure for viral infections, so it is best to remove the infected plants to prevent the spread of the disease.
Pest Management
Arabis sparsiflora can be affected by several pests. The most common pests that can infest these plants include:
Aphids
Aphids are small, pear-shaped insects that can be found on the undersides of leaves. They suck the sap from the plant, causing stunted growth and deformities. To manage aphids, use a strong jet of water to wash them off the plant or use an insecticidal soap spray.
Spider mites
Spider mites are tiny, eight-legged pests that cause yellow stippling on the leaves. They thrive in dry conditions, so regularly misting the plant can help to deter mites. Use an organic miticide treatment if necessary.
Mealybugs
Mealybugs are small, white, cottony insects that can be found on the leaves and stems of the plant. They suck the sap from the plant and can cause yellowing and wilting. To manage mealybugs, use an insecticidal soap spray or horticultural oil to suffocate the pests. You can also use a cotton swab dipped in alcohol to remove them manually from the plant.
Regular monitoring of the plant's health can prevent or mitigate pest and disease problems. Prompt action and proper treatment are key to managing and preventing infestations and infections.
