Plant Description:
Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins, commonly known as Arctic rockcress, is a small perennial plant that belongs to the Brassicaceae family. The plant is native to Alaska and the North Pacific region, including parts of Russia and Canada.
General Appearance:
The plant grows up to a height of 10-20 cm and has a clumping, cushion-like habit. The leaves are evergreen, dark green, and form a basal rosette. The leaves are spoon-shaped and have a glossy texture on both sides.
The flowers of Arabis holboellii var. pinetorum appear from May to June and are white or pink in color. The flowers are small, with four petals arranged in a cross shape. The plant is self-fertile and produces small seeds that are dispersed by wind and water.
Common Names:
Arctic rockcress is also commonly known by other names, including Holboell's rockcress, Holboell's arabis, and Alaska rockcress.
Uses:
The plant has no known medicinal or commercial uses. However, it is valued for its ornamental value in alpine gardens and rock gardens. It is also used in native and wildlife gardens to attract pollinators such as bees and butterflies.
Growth Conditions for Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins
Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins is a perennial herb that grows in mountainous areas. It requires specific conditions for optimal growth.
Light
This plant requires full sun to partial shade. It grows best in locations with plenty of natural light, but it can also grow in areas with partial shade. The plant needs a minimum of six hours of sunlight daily for optimal growth.
Temperature
The plant is adapted to cool and moist environments. It requires cool temperatures for optimal growth. The ideal temperature range is between 40°–70°F (4°–21°C). The plant cannot tolerate excessive heat, and under extreme heat, it can wither and die.
Soil
The plant requires well-drained soils that are moderately rich in organic matter. The pH of the soil should be slightly acidic, ranging from 5.8 to 6.5. Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins requires moist soil, but it cannot tolerate waterlogging. The soil must be consistently moist, but not waterlogged to ensure optimal growth.
Cultivation Methods for Arabis holboellii Hornem. var. pinetorum
Arabis holboellii Hornem. var. pinetorum is commonly known as Holboell's rockcress. This plant requires a well-drained soil that is enriched with organic matter. It grows well in full sun or partial shade. It is best to plant this species in late spring or early fall. Prepare the soil well by removing weeds and any rocks that may impede root growth. This plant is not prone to many pests or diseases.
Watering Needs for Arabis holboellii Hornem. var. pinetorum
This species requires regular watering during its first growing season to establish its roots. Once established, it should be watered regularly, but not excessively. Watering should be done at the base of the plant and not on the foliage to avoid leaf spots and fungal diseases. It is advisable to water early in the morning or later in the afternoon to avoid water evaporation. Mulching around the plant can help keep the moisture locked in the soil, and reduce the frequency of watering.
Fertilization of Arabis holboellii Hornem. var. pinetorum
During the growing season, Holboell's rockcress requires a balanced fertilizer that is rich in nitrogen, phosphorus, and potassium. A slow-release fertilizer is preferable as it releases nutrients gradually over a long time. The frequency of fertilization depends on the soil type and the growth rate of the plant. It is always best to test the soil prior to fertilization as over-fertilization can lead to leaf burn, and in extreme cases, cause the plant's death.
Pruning Arabis holboellii Hornem. var. pinetorum
Pruning of Holboell's rockcress is unnecessary as it is a low-growing plant that does not require shaping. Deadheading is recommended, however, to encourage continuous blooming and prevent the plant from self-sowing. Prune any dead or diseased branches, or any that detract from the plant's overall appearance, at any time of the year. If the plant outgrows the intended area, it can be divided in late summer or early fall.
Propagation of Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins
Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins is a herbaceous plant that belongs to the Brassicaceae family. The plant is native to North America and is known for its small white flowers that bloom in early spring.
Seed Propagation
One of the most common methods of propagating Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins is through seed propagation. The plant produces small seeds that can be harvested and directly sown into the soil in early spring. The seeds should be sown at a depth of approximately 3 mm and spaced apart by around 10 cm. The soil should be well-draining and kept moist until the seeds germinate.
Alternatively, the seeds can be sown in seed trays filled with a soilless mix. The trays should be kept in a warm, well-lit location and watered regularly. Once the seedlings have developed their true leaves, they can be transplanted into individual containers or directly into the garden.
Vegetative Propagation
Another method of propagating Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins is through vegetative propagation. This can be achieved through division or stem cuttings.
To propagate through division, dig up the plant in early spring and gently separate the clumps into smaller sections. Replant the sections in well-draining soil and water thoroughly.
To propagate through stem cuttings, take cuttings from healthy plants in mid-summer. Remove the lower leaves from the cutting and dip the cut end into rooting hormone. Plant the cutting in a soilless mix and keep it moist until roots have formed.
Regardless of the propagation method used, it is important to provide the new plants with adequate water and sunlight to ensure their healthy growth and development.
Disease Management
Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins is susceptible to various disease-causing pathogens such as fungi, bacteria, and viruses. Here are some of the common diseases that might affect the plant and ways to manage them:
Downy Mildew
Downy mildew is a fungal disease that leads to yellowing and curling of leaves, stunted growth, and premature leaf drop. To manage the disease, remove infected plant parts, improve air circulation by spacing out plants, and avoid overhead watering. Fungicides containing copper or mancozeb can also be used to control the disease.
Black Rot
Black rot is a bacterial disease that causes yellowing and wilting of leaves, dark lesions on stems and petioles, and eventual death of the plant. To control the disease, remove and destroy infected plant parts, avoid overwatering and overcrowding, and disinfect pruning tools between cuts. Copper-based fungicides can also be used to manage the disease.
Mosaic Virus
Mosaic virus causes mottled leaf discoloration, stunted growth, and deformed flowers. The virus is transmitted through sap, infected tools, and insects. There is no cure for mosaic virus, and infected plants should be removed and destroyed right away to prevent spread. To avoid infection, use only healthy plant material, disinfect tools between cuts, and control insect vectors.
Pest Management
Various pests can also attack Arabis holboellii Hornem. var. pinetorum (Tidestrom) Rollins and cause damage to the plant. Here are some of the common pests that might affect the plant and ways to manage them:
Aphids
Aphids are small, sap-sucking insects that can cause leaf curling, stunted growth, and yellowing of leaves. To manage aphids, wash them off with a strong stream of water, introduce natural predators like ladybugs and lacewings, and use insecticidal soap or neem oil.
Spider Mites
Spider mites are tiny, eight-legged pests that feed on plant sap, causing yellowing and stippling of leaves. To manage spider mites, increase humidity levels by misting the plant, prune affected plant parts, and use insecticidal soap or neem oil. Biological control agents like predatory mites can also be used to manage spider mites.
Cabbage Worms
Cabbage worms are smooth, green caterpillars that can cause damage to leaves, stems, and flowers. To manage cabbage worms, pick them off by hand, use row covers to prevent adult moths from laying eggs, and use Bacillus thuringiensis (Bt) to control the larvae.
