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Growing Cattleya orchids indoors
Few orchids capture the imagination quite like cattleyas. With their dazzling colours, bold flowers, and often intoxicating fragrance, they are known as the Queen of orchids for good reason. While they are spectacular plants, success comes from understanding their natural growth rhythms, cultural needs, and the subtle variations between different species and their hybrids.
OVERVIEW
The genus Cattleya currently includes around 135 recognised species and just over 100 natural hybrids (Source: Kew.org 2025). Many of the species are found in the background of thousands of artificial hybrids that have been created. Historically, orchids with similar features were grouped under Cattleya but DNA studies have reclassified some into related genera such as Guarianthe and Rhyncholaelia. Similarly, many genera that were once separate, such as Sophronitis and the Brazilian laelia have been merged with Cattleya.
Cattleyas are sympodial orchids that grow horizontally (or vertically) along a rhizome, forming enlarged storage organs known as pseudobulbs at 90 degrees to the rhizome. One or two fleshy leaves develop from the top of the pseudobulb and roots grow from the rhizome. Pseudobulbs are designed to store water so that the plants survive dry periods in their natural habitat, as well as nutrients for producing flowers and new growths. Apart from photosynthesis, the leaves also store moisture.
A typical annual rhythm generally follows four stages:
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New growth (spring–early summer) – new growths form from the previous year’s pseudobulbs and elongate, producing leaves
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Maturation (summer) – pseudobulb swells and reaches full size, often producing a bud sheath
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Flowering (autumn or later) – blooms emerge, lasting 2–6 weeks
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Rest (winter) – growth slows or stops as the plant conserves energy
Not all species (and their hybrids) follow this order - some grow during winter, others flower after resting. It’s important to observe your plant’s natural patterns and learn about conditions in their habitat.
Cattleya Valentine 'Coerulia'
Cattleya Rth Robert Strait Tzeng-wen 'Lace'
Growing root tip
Emerging bud on miniature Cattleya
INDOOR CARE ESSENTIALS
■ Light
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Bright, indirect light (3,000–5,000 foot-candles) or a hand held 30cm above the leaves at noon should cast a distinct - but not sharp - shadow
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South or east-facing windows, with sheer curtains to protect from midday sun
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Use grow lights for 12–14 hrs/day in winter. Depending on latitude, supplementary light may also be required in spring and autumn
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Leaf colour: apple green = healthy; dark green = too little light; yellow/red = too much light
■ Temperature
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Daytime average high: 25°C (avoid extended periods of temperatures above 32°C)
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Nighttime average low: 15°C
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Some species and hybrids prefer slightly lower temperatures and others require a slightly warmer overnight temperature
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If temperatures are lower than ideal, keep plants drier
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Maintain good airflow around plants at all times
■ Watering and humidity
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Spring–autumn: water every 7–10 days – if potting medium is still moist, delay till drier
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Winter: water every 10–14 days. If medium is still moist, delay till drier
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Always water thoroughly so it runs out of the bottom of the pot, letting medium dry out slightly before watering again
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Ideally use rain, reverse osmosis (RO), or distilled water. Occasionally tap water will not harm plants. Never use water that has been softened with salts.
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Humidity 50–70% with trays, humidifiers, or by grouping plants together
■ Fertilising
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Growing season: Every week with dilute orchid fertiliser, flushing with plain water every fourth watering
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Rest period: there is no benefit in feeding an orchid that isn’t growing
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Balanced (20N-20P-20k) or high-nitrogen(N) (30N-10P-10K) during growth, switch to high-potassium (K) before flowering
■ Potting and repotting
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Potting Mix: medium to coarse bark mix with horticultural charcoal or perlite. Inorganic media such as leca or lava rock
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Repot every 2–3 years or when medium breaks down or the plant outgrows the pot
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Best time: when new roots begin growing. Take care not to damage emerging root tips as they will not recover. Allow new roots to reach 2-3cm in length before repotting
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Do not cut off old pseudobulbs unless they are soft and discoloured - the same applies to roots
Developing buds on bifoliate Cattleya
VARIATIONS
Unifoliate – one leaf per pseudobulb (e.g. C. labiata, C. mossiae, C. trianae). Large, dramatic blooms once a year. Need bright light and a defined rest.
Bifoliate – two or more leaves per pseudobulb (e.g. C. amethystoglossa, C. bicolor, C. guttata). Many medium-sized flowers, prefer warmth and stable humidity. Roots are delicate—repot with care when there are signs of new root growth.
Miniature and compact – smaller types (e.g. C. walkeriana, C. nobilior, modern hybrids). May bloom more than once a year. Need slightly warmer winters and more frequent watering.
SUMMARY
Bear in mind that as you deepen your knowledge about orchids you will discover many cultural techniques of growing that will contradict with each other, based on the conditions and the type of medium used to grow your plants. For beginners, the hybrids are often a more tolerant option with slightly less rigid requirements than some of the species. The secret, however, to thriving cattleyas is to match care to their natural growth cycle. Whether dramatic unifoliates, floriferous bifoliates, or charming miniatures, each rewards attention with dazzling blooms and often unforgettable fragrance. With the right balance of light, water, feeding, and rest, these orchids will flourish year after year - even on a temperate northern hemisphere windowsill.