Orchids belong to one of the oldest, most highly evolved plant families. No one is absolutely certain how many species exist, but estimates range from 25,000 to 30,000. For centuries, orchids were largely confined to the hothouses of the very wealthy. But the advent of tissue culture—a modern, commercially viable method of propagation—has resulted in an explosion of new cultivars, many of them bred specifically for windowsill growing in any home.
The majority of orchids that can be grown indoors come from tropical regions where conditions are similar to those found in the average Canadian home: consistently moderate to warm temperatures. One element we can’t mimic entirely, though, is the high humidity that most orchids require. To provide the extra moisture they need, place orchid pots in a deep tray lined with gravel or pebbles: fill the bottom of the tray with water, which will evaporate into the surrounding air. (Never allow pot bottoms to sit in water, as this causes root rot.)
Many orchid pots are made from terracotta, but in our relatively dry homes, plastic containers are preferable, as they hold the humidity around the plant better; either way, pots must have drainage holes in the bottom. Fast-draining, bark-based, commercial potting mixtures formulated for orchids are best. Orchids rarely need repotting—generally, the need to repot is brought about by the presence of root rot due to overwatering.
Tips and tricks for your orchids:
Oncidium cvs., such as ‘Gower Ramsey,’ ‘Howeara Lava Burst,’ Sharry Baby (‘Sweet Fragrance’) and Sweet Sugar (‘Emperor’).
Description: Airy sprays of small yellow and brown flowers; new cultivars come in white, purple or vermillion.
Light and temperature: True Oncidium species vary widely in their requirements, so stick to those intended for windowsill culture. Average to high intensity and duration, one hour of direct sun per day, maximum. Place 50 cm from south-, east- or west-facing window Nighttime low 12ºC, daytime high 30ºC; can tolerate up to 38ºC for short periods.
Water: Moderate requirements; irrigate well and allow to dry between waterings so plant does not sit in water; lightly mist leaves in the morning to increase humidity; reduce water if plant goes into a rest cycle during the winter (it will stop producing new leaves, but otherwise appear healthy).
Fertilizer: Orchid fertilizer (19-31-17), or plant food (20-20-20) applied at half-strength, every second watering when plants are in active growth; do not feed during the winter.