Origin and Natural Habitat
Pachypodium rosulatum is native to central Madagascar.
Plant Characteristics
Pachypodium rosulatum is one of the most attractive caudiciform Madagascar Pachypodiums. Its main stem or caudex is rounded and bottle-shaped, with multiple elongated stems sprouting from it. It is a medium semi-shrub, with the main caudex usually reaching about 30cm in height with multiple spread ‘arms’. It produces bright-yellow flowers in early summer.
Care Guide
Light
Pachypodium prefers a sunny location in the greenhouse. It can be adjusted to full morning sun, but it is generally best to keep it under at least 40% shade cloth to prevent stress.
Soil
Pachypodium as a genus requires a very well-draining soil mixture with plenty of gritty components. A medium with akadama and pumice is preferred.
Water
In cultivation, Pachypodium can be watered well during the warmer months. However, it is important to keep this plant dry during winter when it is dormant. Stop watering when it loses its leaves in late autumn and resume when it sprouts again in spring.
Pot size
Pachypodium rosulatum can become quite large when mature. A 10cm pot will be sufficient initially for seedlings, but as the plant grows older and the stem widens, it should be planted in a pot that is 3-4cm wider than its main stem.
Temperature
Pachypodium rosulatum’s ideal temperature ranges between 20 – 35°C. It can tolerate 1 – 40°C. This species is semi-tolerant to frost, but only if it is kept completely dry in winter, once temperatures reach 10°C or less. It is however best to protect it from frost completely as survival is not guaranteed.
Humidity
Pachypodium rosulatum is somewhat sensitive to humidity due to their semi-arid natural habitat. Make sure that your growing space has plenty of airflow.
Fertilizing
Use a half-strength diluted general liquid fertilizer only during the growing season. Do not fertilize during winter. Alternatively, a small amount of slow-release fertilizer will be sufficient.
Growing season
Pachypodium rosulatum only grows during spring and summer.
Propagation
Pachypodium rosulatum can be propagated from seed germination. Cuttings are possible, but not advisable as they rarely root.
Seed germination: Seeds should be sown in late spring or in summer. Temperatures need to be 28-30°C at minimum for successful germination. Plant the seeds in a coco peat mix in an airtight container, about 5mm under the soil. Once most of the seeds have germinated, remove the lid of the container to allow airflow. Gently water the seedlings every few days so that the soil does not dry out.