Origin and Natural Habitat
Pelargonium triste is native to South Africa, specifically to the Northern and Western Cape.
Plant Characteristics
Pelargonium triste is a tuberous caudiciform species. The tuber is generally found underground in nature, but can be lifted to create an attractive bonsai-like appearance in cultivation. Produces white and purple flowers from August to February (in South Africa).
Caudex shape may differ from the photos, each plant is unique.
Care Guide
Light
It prefers a lightly shaded location in the greenhouse. If this plant is kept outdoors, but not in a greenhouse, then full morning sun is suitable.
Soil
The Pelargonium triste requires a very well-draining soil mixture with plenty of gritty components. A medium with akadama and pumice is preferred.
Water
In cultivation, Pelargonium triste can be watered well during the cooler months, once it has grown its first leaves. However, keep completely dry in summer when it does not have leaves. Let the plant tell you when to water it: Water when it has leaves, keep it dry when it does not have leaves. This species is extremely prone to rot if it is watered when it is dormant.
Pot size
Pelargonium triste can grow quite large tubers/caudexes, and their pot size should accommodate for this. For the first 2-3 years of life, a 10cm pot will be sufficient. As they grow older, plant this species in a pot that is 5cm wider than its tuber to accommodate new growth. Deep pots are preferred, as they will grow more vigorously if their roots have room to expand into the soil. This species can be grown as garden plants in winter rainfall regions, but care should be taken to provide good quality, well-draining soil.
Temperature
Pelargonium triste‘s ideal temperature ranges between 15 – 25°C. It can tolerate -5 – 40°C. Young plants are susceptible to frost damage to both their tuber and leaves.
Humidity
Pelargonium triste are sensitive to humidity due to their semi-arid natural habitat, and particularly so when dormant. 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 summer. Alternatively, a small amount of slow-release fertilizer will be sufficient.
Growing season
Pelargonium triste grows during autumn, winter and early spring.
Propagation
Pelargonium triste is best propagated by sowing seed.
Seed germination: Seeds should be sown in early autumn. Plant the seeds in a coco peat mix in an airtight container, and cover them with some sifted coco peat. 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. The container should be relatively deep to accommodate their root systems.