The genus Stanhopea, previously also known as Ceratochilus, Stanhopeastrum, Gerlachia, or Tadeastrum, belongs to the Orchidaceae family and was described by William Jackson Hooker in 1829, who named the genus in honor of the fourth Earl of Stanhope (Philip Henry Stanhope), president of the Medico-Botanical Society of London. The natural range of the genus Stanhopea includes Mexico, up to northwestern Argentina, in Central and South America, where it inhabits humid forests at altitudes from sea level to over 5000 m.
Most Stanhopea species bloom in summer and only some during autumn. The flowers, strongly fragrant, have a short lifespan, lasting only 3 – 4 days, and generally emerge through the lower area of the planting baskets, creating the impression that the plants are overturned. The scent suggests spicy notes, and Stanhopea species are known for successive, repeated bloomings several times throughout the year
Stanhopea species have epiphytic growth, occasionally terrestrial. They have ovate pseudobulbs with a single long, elliptical leaf inserted apically. In the natural environment, the aerial roots of species in this genus often grow oriented upwards, forming a nest-like structure where dead leaves and dust accumulate, thus providing nutrients to the plants.
Light intensity requirements of Stanhopea species are in the range of strong diffuse light, approximately 25000 – 30000 lux, similar to species of the genus Cattleya, but avoiding direct sunlight, which can cause severe sunburn on the leaves. It is advisable to provide additional shading during the summer when daytime temperatures exceed 34 degrees Celsius.
Growth temperature, reflecting the origin of Stanhopea species from tropical and subtropical regions, but also occupying some high-altitude mountainous areas, is generally in the range of low temperatures. Some tropical species, such as Stanhopea annulata, avicula, candida, cirrhata, ecornuta, and grandiflora require night temperatures above 18 °C to ensure successful flowering. As a general rule, most tropical species require minimum night temperatures of 12 °C. Higher temperatures can reach the limit of 30 – 35 °C without causing significant problems in the cultivation of these species.
The Stanhopea orchid generally requires a high level of atmospheric humidity throughout the year, which is why frequent misting is recommended during the summer. Due to the high humidity level required by these species, ensuring very good ventilation is recommended to prevent the development of fungal and bacterial diseases.
The ideal growing method for the Stanhopea orchid involves placing the plants in a wire basket with large holes, at least 1 cm in diameter, allowing the pendant flowers to penetrate the base of the growing container. Wooden baskets and standard pots can prevent this, leading to failures in flowering. As a substrate, coconut fiber, medium to fine pine bark, ideally mixed with sphagnum moss, perlite, or Osmunda fern fibers can be used to ensure a loose, airy, light growing medium with very low compaction and strong drainage. The most impressive blooms come from large, vigorous specimens, which is why excessive division of Stanhopea species is not recommended.
Repotting will be done infrequently, approximately every 3 years, and generally avoided, as it can delay flowering by up to 12 months. The ideal time for this intervention is summer, immediately after flowering has finished.
Watering can be done 2 – 3 times a week in the warm season (monitoring the temperature-humidity ratio), and will be accompanied by daily misting during very hot periods to ensure constant humidity. In the cold period, watering the leaves will be avoided, as this can lead to bacterial leaf spots. For species of Central American origin, complete drying of the substrate during winter will never be allowed, as the plants are very sensitive to salt accumulation in the substrate. Some species, such as Stanhopea hernandezii, insignis, jenischiana, leitzei, maculosa, and martiana come from regions with dry winters, which is why it is recommended to reduce watering and provide a high light level during the winter period. For these species, the normal watering schedule will resume once new growth is observed in spring.
Fertilization is done at regular intervals, with a 25% dilution of the recommended dosage on the package, every 2 weeks. For plants grown in bark, a 30 – 10 – 10 formula rich in nitrogen will be used, alternating with a balanced 20 – 20 – 20 formula. For the flowering season, a 10 – 30 – 20 formula will be used to stimulate flowering.
The Stanhopea orchid does not require a resting period to stimulate flowering, nor a rest during the cold season. Failed flowering is most often due to insufficient watering during the summer, weak temperature differences from day to night in spring, or too low humidity.
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