Overview
Lobelia krookii Zahlbr. is a rare species of herbaceous perennial plant belonging to the family Campanulaceae. It is endemic to New Zealand and is characterized by its unique appearance and medicinal properties.
Common Names
The plant is commonly known as Krook's lobelia, Krook's bluebell, or by its Maori name, Heketara.
Appearance
The plant features bright blue flowers with a white throat, grouped in large clusters on stems that grow up to 40cm tall. The leaves are lance-shaped, grayish-green, and grow alternately along the stems. The plant generally blooms in spring and summer.
Uses
Lobelia krookii Zahlbr. has been traditionally used by the Maori community as a medicinal herb for treating respiratory illnesses such as asthma and bronchitis. The plant contains alkaloids that act as respiratory stimulants and are known to have anti-inflammatory and analgesic properties. However, caution should be taken as the plant can be toxic if ingested in large doses.
In addition to its medicinal properties, Krook's lobelia is also an attractive garden plant and is grown for ornamental purposes. The plant prefers moist to wet soils and partial shade, making it an ideal plant for wetland habitats or as a border plant for gardens and landscapes.
Light Requirements
Lobelia krookii Zahlbr. prefers partial shade or filtered sun as it cannot tolerate direct or intense sunlight. Therefore, it should be planted in areas with dappled shade or under the canopy of taller plants or trees.
Temperature Requirements
This plant is native to the highlands of East Africa where it grows in cooler temperatures ranging from 10°C (50°F) to 25°C (77°F). Therefore, it thrives in moderate temperatures and may suffer in hot and humid climates or extreme cold temperatures.
Soil Requirements
L. krookii Zahlbr. prefers well-draining soil with a pH range of 5.5 to 6.5. The soil can be sandy, loamy, or clayey, as long as it is fertile and not waterlogged. Additionally, it benefits from a layer of organic matter added to the soil to improve soil texture and moisture retention.
Cultivation Methods
Lobelia krookii Zahlbr. is a sun-loving perennial plant that thrives in areas with mild temperatures. It prefers well-draining soil, ideally with some organic matter blended in, to grow to its fullest potential. The plant requires a neutral to slightly acidic pH level of between 6.0-7.5. As a tall and leggy-type plant, Lobelia krookii Zahlbr. requires staking, particularly if planted in an open area exposed to strong winds.
Watering Needs
Lobelia krookii Zahlbr. prefers to be kept moderately moist, with watering once a week for plants grown in pots and twice a week for plants grown in the soil. Overwatering can cause root rot, so the soil must not be allowed to become waterlogged. Lobelia krookii Zahlbr. is sensitive to drought, and watering must not be neglected, as prolonged drought can negatively impact the flowers and the quality of the plant.
Fertilization
Lobelia krookii Zahlbr. requires regular fertilization to encourage lush leaves and profuse flowering. Regularly feed the plant with a balanced water-soluble fertilizer every three weeks during the active growing season. Using additional manure or other organic matter rich in nitrogen may help the plant grow. Supplementing with micronutrients such as iron, magnesium, and calcium is necessary to maintain healthy foliage coloration and strong stems.
Pruning
Pruning Lobelia krookii Zahlbr. is necessary to maintain its aesthetic value. Prune anytime during the growing season to remove dead flowers, leaves, and stems. During the growing season, trim back the plant by about 1/3 after the first wave of blooming. This encourages the plant to regrow and bloom again.
Propagation of Lobelia krookii Zahlbr.
Lobelia krookii Zahlbr., commonly known as Krook's lobelia, is a mat-forming perennial plant native to New Zealand. It produces blue-violet flowers in summer and grows up to 5 cm in height. Propagating Lobelia krookii Zahlbr. can be done through various methods, including seed propagation, root division, and cuttings.
Seed Propagation
The most common way to propagate Lobelia krookii Zahlbr. is through seeds. The seeds are small, black, and require gentle handling. Collect seeds from dried seed capsules. Sow the seeds on a seed tray filled with a good quality seed-raising mix. Keep the tray in a warm, sheltered location and mist the soil regularly to keep it moist. The seeds will germinate in 2-3 weeks, and the seedlings can be transplanted to individual pots once they develop their true leaves. Lobelia krookii Zahlbr. does not transplant well from seedlings, so plant them carefully and do not disturb their roots.
Root Division
Root division is another way to propagate Lobelia krookii Zahlbr. This method is best done in early spring or autumn. Dig up the clump of Lobelia krookii Zahlbr. and carefully separate the roots. Each division must have a few healthy roots and a growth point. Replant the divisions in well-draining soil and water them well. Be sure to keep the soil moist until the plant establishes itself.
Cuttings
Propagation of Lobelia krookii Zahlbr. can also be done through cuttings. Select healthy stems from the parent plant and cut them into 5 cm pieces. Remove any leaves from the bottom half of the cutting. Dip the cut end into rooting hormone powder and plant the cuttings in a pot with well-draining soil. Water the cuttings immediately and cover them with a plastic bag or a cloche to maintain high humidity. Keep the soil moist but not waterlogged. The cuttings will root in 2-3 weeks, after which they can be transplanted into individual pots.
Disease and Pest Management for Lobelia krookii Zahlbr.
Lobelia krookii Zahlbr. is a delicate and beautiful flowering plant that requires proper care and management to avoid damage caused by pests and diseases. Here are some common diseases and pests that may affect the plant and suggestions on how to manage them:
Common Diseases
Fungal Diseases: Lobelia krookii Zahlbr. is susceptible to fungal diseases like root rot, powdery mildew, and rust. These diseases can cause the plant's leaves to wilt, turn yellow, and sometimes die. To manage fungal diseases, remove infected plant parts, avoid watering the plant from above, and maintain proper air circulation around the plant. Also, ensure the soil is well-draining and not waterlogged.
Bacterial Diseases: Bacterial diseases like bacterial blight can affect the plant, causing brown spots on the leaves, stems, and flowers. These spots can grow and eventually kill the plant. To manage bacterial diseases, promptly remove and destroy infected plant parts, avoid overhead watering, and apply copper-based fungicides.
Common Pests
Slugs and Snails: Slugs and snails love to feed on the leaves of Lobelia krookii Zahlbr. These pests can leave large holes in the plant's leaves, making it look unsightly. To manage slugs and snails, remove any hiding places around the plant and use beer traps or copper tape barriers as deterrents.
Spider Mites: Spider mites are tiny pests that feed on the plant's sap, leaving discoloration and damage on the plant's leaves. To manage spider mites, remove and destroy any infected plant parts and avoid overcrowding the plant. You can also use insecticidal soap or neem oil to control the pests.
Aphids: Aphids are small, soft-bodied insects that suck sap from plants, causing stunted growth and yellowing of the leaves. To manage aphids, remove and destroy infected plant parts, use strong jets of water to wash off the pests, and use insecticidal soap or neem oil to control severe infestations.
Overall, good plant hygiene, proper watering, regular inspection, and prompt action are essential in managing pests and diseases in Lobelia krookii Zahlbr.
