Propagation of Temperate Terrestrial Orchids

Vegetative Propagation

Propagation from Seed

Propagation of orchids can be a rewarding pastime for those with the ability to accept delayed gratification! Orchids commonly require four-five years or more from sown seed to first flower! In addition, propagation of many temperate terrestrial orchids from seed remains difficult. However, because Cypripedium and Dactylorhiza are such showy genera, methods have been developed capable of producing thousands of seedlings per year of some species.

Unlike seed of most other plants, orchid seed does not contain nutrients to support the growth of the embryos, and young seedlings of many species of terrestrial orchids have no chlorophyll to capture energy to manufacture their own nutrients. In order to germinate orchid seed, growth media containing simple sugars, amino acids, and a variety of vitamins and hormones is required. Such media also serve as excellent growth media for molds, funguses, and bacteria! Thus, to successfully propagate orchids from seed one must sterilize both the seed and the media in which they are to germinate and grow. While sterile propagation of seed is often done using specialized, expensive equipment, for those who wish to perform only a few crosses, there are very effective methods that require no specialized equipment at all and which may be accomplished in the kitchen. At Gardens at Post Hill, sow many capsules each year, so we do use some specialized equipment and methods so that we can handle several pods each day.

Propagation of orchid seed consists of several steps:

Pollenation
Collecting and Processing Seed
Sowing seed
Reflasking
Deflasking
Vernalization
Planting Out

Pollenation

To propagate seed, a fertile pod is required (actually orchid fruits are capsules but most propagators refer to the fruits as 'pods.' One may depend upon insects to pollenate flowers but this is a hit or miss proposition. It is much simpler to artificially pollenate specimens of interest. Once your flower has been pollenated, the pod will begin to develop. At this point, you must decide whether you will attempt to germinate the seed yourself or instead prefer to send the pod to a flasking service that for a fee will sow your seed and send you seedlings at specified maturity.

Collecting and Processing Seed

Seed ripening in many tropical epiphytic orchids may require many months. However, the seed of temperate terrestrial orchids mature very rapidly since the stems die back each fall.

Immature vs Mature Seed

To avoid germination during the cold winter months the seed of many temperate terrestrial orchids produce "inhibition substances." Once these inhibition substances are present, seed will not germinate even after sowing until they have passed through a winter (called vernalization or stratification). For some species, storage of seed in a refrigerator for several months at 33 F to 39 F is enough to overcome the effects of the inhibitory factors, whereas for other species of orchids, breaking seed dormancy on demand is still impossible. For some of these species, using immature capsules or "green pods" allows embryos to be removed and sown on media before inhibitory factors are produced, and since the embryos are rapidly growing, when they are placed onto sterile medium they develop into seedlings rapidly.