Arabis holboellii Hornem.
Arabis holboellii Hornem, also known as Holboell's rockcress, is a species of flowering plant in the family Brassicaceae.
Origin
The plant is native to North America, specifically in the Northern Arctic and Subarctic regions of Canada, as well as Alaska and Greenland.
Common Names
Besides Holboell's rockcress, the plant is also known as Holboell's arabis and Arctic rockcress.
Uses
Arabis holboellii Hornem is a common plant in rock gardens and wildflower meadows. It is also used in landscaping and erosion control projects.
General Appearance
The plant grows up to 30 cm tall and has small white flowers that bloom from May to September. The leaves are generally narrow and oblong-shaped and are covered in soft hairs. Its stem is thin and wiry and can grow to be several centimeters long.
Growth Conditions for Arabis holboellii Hornem.
Arabis holboellii Hornem., commonly known as Holboell's rockcress, is a herbaceous perennial plant belonging to the Brassicaceae family. The plant is native to Greenland and North America and can be found growing in rocky areas, coastal cliffs, and alpine tundra regions.
Light Requirements
Arabis holboellii Hornem. thrives in full sunlight and requires at least six hours of direct sunlight per day. However, the plant can also tolerate some shade, but it may reduce flower production.
Temperature Requirements
The plant prefers cold climates and can survive in USDA hardiness zones 2 to 7. The optimal temperature range for growth is between 10-15°C, but it can tolerate temperatures as low as -20°C. However, hot temperatures can harm or even kill the plant. Therefore, it is advisable to cultivate Arabis holboellii Hornem. in shaded locations in warmer regions.
Soil Requirements
The plant prefers well-drained soil with a pH range of 6.0 to 8.0. The soil should be rich in organic matter and have good water-holding capacity. Arabis holboellii Hornem. can tolerate soils in different textures, including clay, loamy, and sandy soils. However, heavy or compacted soils can hinder root growth and reduce nutrient uptake, leading to stunted plant growth.
Cultivation of Arabis holboellii Hornem.
Arabis holboellii Hornem. is a hardy and adaptable plant that can grow in a variety of soil types. It prefers well-draining, slightly acidic soil with a pH of 5.5 to 7.5 but can tolerate alkaline soil up to pH 8.
Sow the seeds of Arabis holboellii Hornem. indoors in early spring under fluorescent lights. Keep the soil moist and maintain a temperature of 65 to 75°F. When the seedlings have three sets of true leaves, transplant them into individual pots and grow them until the last frost.
After the last frost, you can move the plants outside, digging a hole twice the size of the root ball, and plant the seedling. Space them approximately 4 to 6 inches apart in the garden bed.
Watering Needs
Arabis holboellii Hornem. thrives in moist soil, but it can tolerate dry conditions. During the first year of growth, water the plants regularly, preferably once a week, and avoiding overwatering. In subsequent years, watering can be reduced, particularly during the hot months, but ensure the soil never gets too dry.
Fertilization
Arabis holboellii Hornem. grows well without fertilization. However, fertilization encourages growth, especially during the flowering period. Consider providing nutrients to the plants in early spring, such as organic matter like compost or a balanced fertilizer with an NPK of 10-10-10. Use the fertilizer at a rate of 1 pound per 100 square feet and water it in thoroughly.
Pruning
Arabis holboellii Hornem. doesn't require much pruning, but it benefits from deadheading, which is the removal of spent flowers. This practice helps to encourage the growth of new flowers, extend the flowering period, and maintain the shape of the plant. If the plant becomes too crowded, thin it out in the spring.
Propagation of Arabis holboellii Hornem.
Arabis holboellii Hornem. can be propagated through three methods: through seeds, stem cuttings, and division.
Propagation through Seeds
Seeds of Arabis holboellii Hornem. can be collected from the plant when they are mature and dry. The seeds can then be planted in well-drained soil or seedling trays that have a good potting mix. The seeds should be covered lightly with soil and kept moist until they germinate.
It is important to note that Arabis holboellii Hornem. has a low germination rate and may take up to a year to germinate. Therefore, it is best to start the seeds indoors and ensure that they receive consistent moisture and light.
Propagation through Stem Cuttings
Stem cuttings of Arabis holboellii Hornem. can be taken from a healthy plant during the growing season. The stem cuttings should be approximately 5-7 cm long and should have at least two nodes. The lower leaves should be removed, and the cutting should be dipped in rooting hormone and planted in a well-draining potting mix.
It is important to keep the soil moist and provide the cutting with filtered light until it develops roots. Once the cutting has established roots, it can be transplanted to a larger container or directly into the garden.
Propagation through Division
Arabis holboellii Hornem. can also be propagated through division. The plant should be dug up carefully, and the roots should be divided into smaller sections. Each section should have at least one strong shoot and root system.
The divided sections should be planted in well-draining soil and watered thoroughly. It is important to keep the soil moist and provide the newly divided plants with filtered light until they establish themselves in their new location.
Disease Management
Arabis holboellii Hornem. is commonly affected by various fungal and bacterial diseases. One of the most common diseases that affect the plant is powdery mildew, characterized by white powdery spots on leaves, stems, and flowers. To manage powdery mildew, it is essential to employ cultural control measures such as proper spacing of plants to promote air circulation, removal of diseased plant parts, and watering the plants in the morning.
Another disease that can affect Arabis holboellii Hornem. is downy mildew, which is characterized by yellow spots on the upper surface of the leaves and a grayish-white, fuzzy growth on the lower surface. To manage downy mildew, it is crucial to avoid overwatering the plants and to provide adequate air circulation. Fungicides such as copper-based products can also be used to manage the disease.
Pest Management
Arabis holboellii Hornem. is susceptible to infestation by pests such as aphids, spider mites, and caterpillars. Aphids can cause damage by sucking sap from the leaves, flowers, and stems, leading to stunted growth and deformation of plant parts. To manage aphids, it is advisable to employ physical control measures such as handpicking or using a strong stream of water to dislodge them from the plants. Insecticidal soap or neem oil can also be used to manage severe infestations.
Spider mites are tiny pests that can cause yellowing, wilting, and dropping of leaves, leading to reduced plant vigor. To manage spider mites, it is crucial to maintain high humidity levels around the plants and to remove any debris that may harbor the pests. Insecticidal soap or neem oil can also be used to manage severe infestations.
Caterpillars can cause significant damage to Arabis holboellii Hornem. by feeding on the leaves and flowers, leading to defoliation and deformation of the plant. To manage caterpillars, it is essential to employ physical control measures such as handpicking or using a Bacillus thuringiensis (BT) insecticide, which is a bacterium that infects and kills the pests.
