Origin and Common Names
Calendula rosmarinifolia Houtt., commonly known as Rosemary-leaved Calendula or Rosemary-leaved Marigold, is a species of flowering plant in the Asteraceae family. It is native to areas in China, Korea, and Japan.Appearance
Calendula rosmarinifolia Houtt. is a perennial herb that grows up to 60cm in height. It has numerous branches that form a bushy shrub. The leaves are grayish-green, narrow, and needle-like, with a strong fragrance reminiscent of rosemary. The flowers are bright yellow to orange in color, with a diameter of 3-5 cm, and are borne on a long stem. The plant blooms from May to July.Uses
Calendula rosmarinifolia Houtt. has various traditional medicinal uses. It is used to treat digestive disorders, inflammation, and skin problems. The plant is also a good source of bioactive compounds such as triterpenoid saponins, flavonoids, and carotenoids, which have various pharmacological properties. In addition, the plant is used in some cosmetic products, particularly those that are designed to improve the appearance and health of the skin. In horticulture, Calendula rosmarinifolia Houtt. is often used as a decorative plant. It is an excellent addition to mixed borders or rock gardens and can also be grown in containers. The plant prefers well-drained soils and full sun to partial shade. It is drought-tolerant, making it a suitable choice for hot and dry regions.Light Requirements
Calendula rosmarinifolia Houtt. thrives in locations with ample sunlight. It requires at least 6 hours of direct sunlight per day to grow properly. Insufficient light may result in weak stem growth and delayed blooming.
Temperature Requirements
This plant grows best in warm temperatures ranging from 60 to 75 degrees Fahrenheit (15 to 24 degrees Celsius). It is not frost tolerant and requires protection during winter months when temperatures drop below freezing. If grown in areas with hot summers, it also benefits from afternoon shade.
Soil Requirements
Calendula rosmarinifolia Houtt. thrives in well-draining soil that is rich in organic matter. A slightly acidic to neutral pH level between 6.0 and 7.0 is ideal for optimal growth. Heavy, compacted soil with poor drainage should be avoided, as it can lead to root rot and other diseases.
Cultivation of Calendula Rosmarinifolia Houtt.
Calendula rosmarinifolia Houtt is a herbaceous annual plant that is native to Europe and Asia. It is a member of the Asteraceae family, and commonly known as the rosemary-leaved marigold. Here are a few tips to help with the cultivation of this plant.
Watering Needs
The watering needs of Calendula rosmarinifolia Houtt. vary based on its growth stage and the prevailing climatic conditions. During the growing season, it is essential to make sure that the soil remains moist, but not waterlogged or excessively wet. To avoid waterlogging or overwatering, consider watering the plants once a week, except during heavy rainfall.
Fertilization
Calendula rosmarinifolia Houtt. prefers slightly acidic soil with a pH range of 5.5 to 6.5. It requires adequate nutrients in the soil for optimal growth. To make sure the soil is rich enough in nutrients, apply a balanced granular fertilizer once a month during the growing season. An appropriate fertilizer should have a higher nitrogen content for green growth and healthy foliage.
Pruning
Calendula rosmarinifolia Houtt. requires minimal pruning to encourage bushy growth and increased bloom production. Deadhead spent flowers regularly to promote re-blooming and a more lush appearance. Cut back any yellow or diseased foliage to prevent the spread of disease.
Propagation of Calendula rosmarinifolia Houtt.
There are several methods of propagating Calendula rosmarinifolia Houtt., including seed propagation, stem cuttings, and division.
Seed propagation
Calendula rosmarinifolia Houtt. can be propagated from seeds. The seeds can be sown directly into the soil after the last frost or started indoors six to eight weeks before the last frost. Sow the seeds in well-draining soil, covering them with a thin layer of soil. Keep the soil moist but not waterlogged. The seeds will germinate in seven to 14 days.
Stem cuttings
Stem cuttings can also be used to propagate Calendula rosmarinifolia Houtt. Cut a 4- to 6-inch stem from the plant, making sure it has at least two sets of leaves. Remove the leaves from the bottom half of the stem. Dip the end of the stem in rooting hormone, and plant it in a container filled with well-draining potting soil. Keep the soil moist and the cutting in a warm, humid environment until roots have formed, usually in three to four weeks.
Division
Calendula rosmarinifolia Houtt. can be propagated through division. Dig up the plant, and separate the roots into smaller sections, each with a few stems and healthy roots. Plant the divided sections in well-draining soil, and keep the soil moist until the plants have established.
Disease and Pest Management for Calendula Rosmarinifolia Houtt.
Calendula rosmarinifolia Houtt., commonly known as rosemary-leaved calendula, is a hardy perennial flowering plant that is widely grown for its medicinal and soothing properties. However, like all plants, it is susceptible to several diseases and pests that can impair its growth and performance. It is essential to identify these problems and implement appropriate measures promptly to protect the plant from damage. Here are some common diseases and pests that affect Calendula rosmarinifolia and their management:
Root Rot
Root rot is a common disease in Calendula rosmarinifolia caused by overwatering or poorly drained soils. The fungi Pythium and Phytophthora can thrive in waterlogged soils, causing root rot and other symptoms like wilting, yellowing, and stunted growth. To manage root rot, avoid overwatering or waterlogging the soil, ensure adequate drainage, and remove infected plants promptly to prevent the spread of the disease.
Gray Mold
Gray mold or botrytis blight is a fungal disease that can affect the flowers and leaves of Calendula rosmarinifolia. It thrives in cool and damp conditions and can cause the plant to wither, decay, and drop leaves or flowers. To manage gray mold, avoid overhead watering, provide adequate spacing between the plants to promote air circulation, and promptly remove infected plant parts to prevent the spread of the disease.
Aphids
Aphids are small, sap-sucking insects that can cause significant damage to Calendula rosmarinifolia plants. They usually infest the leaves, stems, and flowers, causing curling, yellowing, and distortion. Aphids can also spread viruses that can weaken the plant. To manage aphids, spray the plant with a strong jet of water to dislodge them, introduce natural predators like ladybugs and lacewings, or apply insecticidal soap or neem oil as a last resort.
Spider Mites
Spider mites are another common pest that can attack Calendula rosmarinifolia, especially in hot and dry conditions. They are tiny insects that feed on the plant sap, causing yellowing, stippling, and webbing on the leaves. If left unchecked, spider mites can cause severe damage to the plant and even kill it. To manage spider mites, increase the humidity around the plant, spray it with a strong jet of water, apply insecticidal soap or neem oil, or introduce natural predators like predatory mites.
Caterpillars
Caterpillars are the larvae of moths and butterflies that can feed on the leaves and flowers of Calendula rosmarinifolia, causing ragged holes and defoliation. They are usually active in the spring and summer months and can quickly multiply if left unchecked. To manage caterpillars, handpick them off the plant, introduce natural predators like birds and parasitic wasps, or apply Bacillus thuringiensis (BT) as a biological insecticide.
Proper disease and pest management are critical for maintaining the health and vigor of Calendula rosmarinifolia Houtt. Implementing preventive measures like maintaining good hygiene, providing proper irrigation and nutrition, and planting resistant varieties can go a long way in reducing the impact of diseases and pests on the plant.
