Sap on Orchids

Q. My indoor orchids all of a sudden have developed some sticky sap on the underside of the leaves and flower stalks.  Is this bad?  And if yes, then what can I do to eliminate this problem.  I wrote to Sunset magazine twice, but haven’t received an answer. August 2014

I love your articles in the Monterey Herald.  They are always so informative.

A. It’s most likely that the sap is produced by very small pests that suck the plant’s juices. These might be aphids, mealy bugs (cottony blobs) or scale (bumps that slide off). Use a bright light to spot them, looking closely at the new leaves in particular. Eliminate the pests by wiping them with rubbing alcohol on a cotton ball or Q-tip.

If t you can’t see any pests, the sap might be produced naturally by some orchids to attract pollinators. If that’s the case, it’s not a problem, but some growers will wipe off the sap with a damp paper towel.

Best wishes.

Growing Terrestrial Orchids

Most orchids are epiphytes, meaning that they grow on another plant. Epiphytes are not parasites, which are plants that scrounge nutrients from another plant. An epiphyte attaches itself to another plant (a tree, usually) and gets moisture and nutrients from the air and rain and sometimes from debris accumulating around it.

To grow an epiphytic orchid, the gardener must reproduce the temperature, humidity and light level that the plant has evolved to require. This is true for all plants, to be sure, but these orchids have become accustomed to very particular environment that can be difficult for the gardener to provide.

Experienced orchid growers claim that success with epiphytic orchids requires only creating the plant’s preferred conditions. This typically includes planting the plant in coarse bark chips to provide ample access to air.

Without denying the accomplishments of amateur orchid growers, I confess to having killed more than my share of epiphytic orchids.

Given that sad history, I am delighted to have discovered hardy terrestrial orchids. These are plants that thrive in well-drained soil and within a moderate climate like that of the Monterey Bay area. Some terrestrial orchids will even take freezing temperatures.

Terrestrial orchids that are popular for home gardens have been described in three groups according to water needs:

  • Upland species include Lady’s Slipper (Cypripedium), Chinese Ground Orchid or Hyacinth Orchid (Bletilla) and Hardy Calanthe (Calanthe);
  • Transitional species include Grass Pink (Calopogon), Marsh or Spotted Orchid (Dactylorhiza), Egret Flower (Habenaria), Fringed Orchid (Platanthera), Fragrant Ladies’ Tresses (Spiranthes), and Helleborine (Epipactis);
  • Wetland species include Rose Pogonia (Pogonia).

Three years ago, I acquired a small Lavender Chinese Orchid (Bletilla striata), which is widely available, and planted it in semi-shade, assuming that all orchids want shade. Although I never watered or fertilized the plant, it grew well but produced only occasional blossoms. This was disappointing because Bletillas often will have as many as 20 flowers on a single spike.

Then I learned that this plant prefers full sun exposure. I lifted it and discovered it had developed about twenty pseudobulbs, which are storage organs (like tubers) that some orchids produce. These can be planted six inches apart, about three inches deep, so I should have several patches of these plants in bloom in the spring.

Terrestrial orchids can provide an exotic display in the garden without requiring extraordinary care. The Chinese Ground Orchid is particularly easy to grow, and the Lady’s Slipper and Hardy Calanthe are also good choices for most gardens. The Transitional and Wetland species require more moisture, making them inconsistent with water conservation goals, but a small display would be tolerable.

If you enjoy the unique beauty of orchids, but have had poor experiences with epiphytic species, growing terrestrial orchids could be an appealing option.


Here are current books about the  cultivation of hardy orchids.My principal reference for this column was the Mathis book, but other books listed offer additional information and other perspectives.

  • The Orchid Manual: For the Cultivation of Stove, Greenhouse, and Hardy Orchids, With a Calendar of Monthly Operations, and Classified Lists of Species, by Thomas Appleby. Forgotten Books (June 23, 2012) (Note: this is a reprint of a classic book published in 1845.
  • Growing Hardy Orchids, by Philip Seaton, Phillip Cribb, Margaret Ramsay and John Haggar. Royal Botanic Gardens, Kew; Original edition (March 15, 2012)
  • Growing Hardy Orchids, by John Tullock. Timber Press (September 15, 2005)
  • The Gardener’s Guide to Growing Hardy Perennial Orchids, by William D. Mathis. The Wild Orchid Company (2005)
  • Hardy Orchids, by Phillip Cribb and Christopher Bailes. American Orchid Society (December 1989)
  • Hardy Terrestrial Orchids for Perennial Gardens with a focus on Bletilla, Calanthe, and Spiranthes – Excluding Cypripedium, by Dennis Carey & Tony Avent. Plant Delights Nursery Inc.

Selected sources of hardy terrestrial orchids: