Cattleya speciosissima (luddemanniana) "Stanleyi" FCC/RHS

Light reigns supreme in the cultivation and blooming of cattleyas, whether they're housed in a greenhouse or nurtured indoors. These plants thrive under bright light conditions, but direct sunlight during midday should be avoided. Optimal light sources include east-facing windows or shaded south or west-facing windows indoors. In a greenhouse setting, providing 50 to 70 percent full sun (equivalent to 3,000 to 5,000 foot-candles) is ideal. Healthy cattleyas boast medium green leaves and erect pseudobulbs, often requiring no additional support.

Temperature control is crucial, with nighttime temperatures ranging from 55 to 60°F and daytime temperatures between 70 and 85°F. Seedlings may require slightly higher nighttime temperatures, typically five to 10 degrees above the standard range. Maintaining a 15- to 20-degree temperature differential between day and night, particularly for mature plants, is recommended. While cattleyas can tolerate higher daytime temperatures up to 95°F, increased humidity, adequate air circulation, and shading become essential under such conditions.

Watering should be approached in two ways: through direct pot watering and atmospheric humidity. Various factors, including pot size, temperature, and light exposure, influence watering frequency. Mature cattleyas benefit from drying out completely between watering sessions, whereas seedlings necessitate more consistent moisture levels. Assessing the pot's weight can indicate watering needs, with a lighter pot signaling dryness and a heavier one indicating saturation. When in doubt, it's advisable to wait before watering again. Cold water below 50°F can harm plants, as can water softened by salt additives.

Maintaining humidity levels between 50 and 80 percent is vital for cattleyas. Indoors, this can be achieved by placing plants on trays filled with gravel and partially submerged in water to prevent direct contact. Adequate air circulation is crucial to prevent fungal or bacterial diseases, particularly in high-humidity or cooler environments. In a greenhouse, humidity levels can be augmented using a humidifier, while evaporative cooling simultaneously increases humidity and cools the air.

Fertilization should occur on a regular basis, employing a high-nitrogen formulation (such as 30-10-10) in fir bark or a balanced fertilizer. During active growth periods, fertilize plants at least every two weeks; during dormant phases, fertilize monthly. Alternatively, fertilizer can be applied at a quarter of the recommended dilution with each watering session. Monthly flushing with clear water helps prevent fertilizer salt buildup.

Repotting becomes necessary when plant rhizomes extend beyond the pot edges or when the potting medium deteriorates, typically every two to three years. Repot just before new roots emerge from the rhizome, after flowering, or in spring. Mature cattleyas are typically potted in coarser material compared to seedlings. Division should occur only when a plant has at least six mature pseudobulbs, with three to five pseudobulbs per division. Choose a pot that accommodates approximately two years of growth, placing firm live roots against one side and filling with medium. Maintain humidity and shade until new root growth is observed.