Orchids on the Windowsill

The secret to success in growing orchids indoors is choosing plants that are best suited to the growing environment. Most orchids fail to bloom because of inadequate light or temperatures that are too consistent.

Test the light. Here's a quick way to test the light for growing orchids indoors: on a bright, clear summer day, hold your hand about six inches above your orchid to see if a shadow is cast on the leaves. A faint shadow indicates that 'low' light orchids may be grown, while a strong, distinct shadow indicates there is enough sun to grow 'high' light orchids.

What's your exposure? Unobstructed southern exposures offer the most possibilities for growing orchids. However, a wide variety of 'high' light and 'medium' light orchids will thrive on windowsills with a western or partially obstructed southern exposure. Eastern exposures will allow bloom of 'low' light orchids. Northern windows frequently don't provide enough light to bloom orchids well, but artificial light can help supplement.

Water. Most orchids prefer to dry out a bit between waterings, although there are some exceptions. When watering, drench the pot thoroughly and drain completely. Never let the plant sit in water. Tepid water is preferred, and it is best to water early in the day so the foliage dries by nightfall. Keep in mind that far more orchids are killed from over-watering than being too dry.

Cooler nights. Many orchids prefer a nighttime drop in temperature. In some, this helps encourage flowering. For several weeks during the fall, leave the windows cracked open slightly at night to allow the daytime temperatures to drop 10 degrees. This should help your orchids set spikes for winter and spring blooms!

Your local orchid society, such as the National Capital Orchid Society, is a great place to find out which varieties do well in your area.

  • 'Low' light orchids: Paphiopedilum (slipper orchids), Phalaenopsis (moth orchids), Ludisia spp. and other jewel orchids (grown for beautiful foliage)
  • 'Medium' light orchids: Oncidium and many miniature Cattleyas, Miltoniopsis (pansy orchids)
  • 'High' light orchids: Cattleya, Ascocenda, Phragmipedium, Brassia and Dendrobium