University of Maryland Extension

Care of Phalaenopsis orchids (moth orchid)

Phalaenopsis (Phals), also known as moth orchids have probably increased the allure of orchid culture for the general public more than any other orchid genus. They are mass produced and are reasonably priced. Phals are readily available in big box stores and the many hybrids are very easy to grow and flower under most home conditions.

General growth characteristics

  •  In nature, Phalaenopsis orchids grow on tree trunks and branches in the warm sections of the tropics worldwide. They tend to hang on tree bark, and send out aerial roots along their stem. For this reason, most of their roots will be above the pot and will commonly sprawl outside the container and even along the shelf surface. This is perfectly normal so do not cut them off.
  • Flower stalks initiate and grow out from the leaf joints or axils. They often set multiple flower buds. The flowers can last for at least a month or longer if the plant is provided  proper care.
  • Flower spikes can be quite tall. They can possibly form flowering branches off the main spike further extending the flowering period. 

 General Care

 Watering:

  • Often orchids come planted in containers filled with chipped bark for drainage which leads to confusion on how to best water the plants. An easy method is to place the plant in a sink or tub. Run warm water over the plant, bark and aerial roots in a series of 3 or 4 drenches over a 10 minute period allowing the water to be gradually absorbed. Allow the water to drain completely before placing it on a saucer and returning it to a sunny window.
  • Aerial roots will turn from a dull silver or white to a pale green color when you have applied enough water. Under normal home temperatures waterings should not be needed more than once a week.
  • Misting an orchid usually does not provide enough moisture under indoor home growing conditions. Pebble trays placed underneath pots can increase the general humidity around plants; however don’t flood these trays or the roots will stay overly wet and may rot.
  • Low humidity and too little water will result in wrinkled leaves. Phals do not have water storage pseudobulbs as many orchids do.

Temperature and Light:

  • Phalaenopsis orchids do well under normal room temperatures with indirect light from an east or west window. During the short days in the winter they can even be moved to direct light or placed in a south window. Orchids can be placed in an interior room or on an office desk if placed under a grow light. 
  • Plants receiving the proper amount of light will have light green leaves. Low light conditions produces leaves that are dark green and feel very stiff. Under very high light the leaves will develop a pink or reddish color along the margins and will appear yellow green or almost yellow. 

 Staking:

  • Prevent bending of the flower stalk by placing a rigid, thin stake made of bamboo, wood or metal beside the stem that needs support. Push it into the growing media being careful not to damage leaves or roots. Secure the flower the stalk to the stake loosely with small plastic clips (small plastic hair clips) or plant ties.

Fertilizing:

  • Phalaenopsis orchids benefit from light fertilization, however over feeding your plants will often result in lush growth at the expense of flowers.
  • As a general rule fertilize actively growing and flowering plants every third or fourth watering with a commercial orchid fertilizer according to label directions.
  • Skip fertilization during the cooler temperatures and lower light intensity of the winter months.

Re-flowering:

  • Light exposure is important for re-flowering. The most common cause for not flowering is low light levels.  
  • Move plants that are not re-flowering indoors either to a brighter window, or put them outdoors in a shady location during the summer months.
  • Another trick to get them to set buds is allowing your plants to experience cooler night temperatures in the fall before bringing them back indoors. Bring them indoors when evening temperatures dip into the fifties.
  • Since Phalaenopsis orchids have the tendency to form new flowering branches along their old flower spikes watch the old spike closely for signs of new buds after the flowers have faded and have fallen off. Or to promote re-flowering, prune yellowed or brown spikes back to about ½ inch above the second node or swelling along the spike above the foliage.
  • Cut off any old yellowed leaves or old, dried, brown flower spikes at the base of the plant. 

Repotting:

  • Under common indoor growing conditions your orchid can last several years before repotting is needed.
  • Clues for repotting include: when the plant has overgrown its pot or the bark has broken down so that it looks like mulch, drains poorly and holds too much moisture. 
  • The best time to repot is when new growth has started and not necessarily after it has finished blooming.
  • Select a commercial orchid bark mix and a container with excellent drainage. Gently knock the plant out of its old pot. 
  • Phalaenopsis orchids grow along the surface of flower pots sending a few roots into the bark growing medium. But if roots have attached to the pot or old bark medium then soak the plant for a long enough period that they can be gently pried off without damage or breakage. Cut off any dead, discolored, or damaged roots, and rinse away the old degraded bark from the plant.
  • Simply suspend the plant over the larger new pot and gently fill in around the bottom roots with new bark until the plant sits on top. Water the newly re-potted plant to further settle the new bark around the roots.

Authors: Dave Clement, Ph.D., Extension Specialist, Plant Pathology and Mary Kay Malinoski, Extension Specialist, Entomology
Reviewer:
Debra Ricigliano, Extension Program Assistant HGIC

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