Orchid seed orchid seeds orchid seed germination asymbiotic orchid seed germination

Orchid seed orchid seeds orchid seed germination asymbiotic orchid seed germination

Hi Nadine!

Nadine Vreeland

Media Selection

The selection of the best medium for your purposes can be a frustrating task. Of course, we want to choose the best media for our purposes, and there are several qualifications for what consititutes the “best” medium. These should be discussed briefly.

What do we mean by the “best” results for orchid seed germination? We want:

1) As high a germination rate as reasonably possible

2) Good growth of protocorms to a reasonable size

3) Minimal progression to larger size such that protocorms are of uniform size, producing better replate flasks

4) Good survival for as long a period of time as reasonably possible to give the flasker plenty of time to replate them

All of these characteristics are important; number 3 requires some explanation for the novice. Although germination may occur quickly, some seeds are slower to germinate or slower to grow than others. If protocorms mature at the same size and seedlings develop at a comparable rate, replate flasks will tend to have seedlings that are of similar size. Rather than a replate flask with HUGE seedlings and tiny seedlings mixed together, it is more desirable to have finished flasks with seedlings with relatively little variation in size.

Sometimes it is unavoidable, and seedlings will do what they darned well please; Stanhopeinae (Stanhopea, Peristeria, Gongora, and Coryanthes) will often do whatever they want, and flasks will be a mixed bag of seedlings of different size no matter what is done to the contrary. Other seedlings tend to grow at a surprisingly steady rate, producing uniform crops of Epidendrum or Encyclia seedlings, for example.

Number 4 also deserves some explaining. For those that have not witnessed it, “brown out” is when protocorms turn brown or yellow while still in mother flask- a sign that you did not act fast enough to get them into replate flask. While there are other causes (high temperatures, for example, for plants that cannot tolerate them), brown-out is often caused by “bad” concentrations of sugars. If you have problems with brown-out, try our pre-mix of P668 with B852 banana powder. It has less banana powder in it than replate flask, but not so much that it inhibits germination. Good stuff.

The following is a table that describes in the most general terms possible the different formulae that we sell for the germination of orchid seeds. “Western Media” consists of our Western seed germination formulae, W2.5 and W3. P668 is the commercially available preparation from PhytoTech Labs, which we also resell. P668 + B852 is our own homebrew mix that we use here for general sowing.

The following table describes, in the most general terms possible, performance characteristics of these media with different genera. There are always exceptions and the grower is urged to experiment to determine the best possible formulae for their conditions.

Special note on Phalaenopsis species: We get in a fair number of different phal species, but they almost never germinate for us. I have suspicions that the dry seed does not live very long, so the seed we get is usually dead. Therefore, I have qualified all of the media as “no data” with this genus. However, P668 was formulated specifically for germination of this genus by Dr. Ken Torres, now at PhytoTech Labs. It should prove useful to those that need to germinate this species (probably from green capsule).

Cymbidiums: Not picky (germinate on Western, P668, or modified P668). Also available is Gallup and Stribling. Their media have never worked well for me, but other growers advise that their media is variable, and sometimes works very well for them.

Paphiopedilum: The entire genus is fraught with peril, and is best left to the experienced grower. Many species are extremely difficult to germinate, or requre specialized media or germination conditions. Some of the more difficult genera may be propagated using techniques adapted for cypripediums and other temperate terrestrials. Western media are formulated to successfully germinate a number of genera, and paphs do quite well on these media. Also highly recommended are media from Alan at Tissue Quick Plant Labs in the UK. The use of media with banana (such as the P668 + B852) is apparently contraindicated with paphs; the use of coconut as an undefined component when mixing W2.5 and W3 is suggested over banana or pineapple. They do not appear to be nearly as fussy about replate media as they are with germination media.

Temperate Terrestrial Species, NOS: What a special group of plants this is. Some offer virtually no resistance to asymbiotic germination; it has been my experience that some Spiranthes will germinate very nicely indeed on “typical” tropical formulae (P668 and P668 + B852), and do quite nicely. I have germinated Bletia florida on P668 and P668 + B852 to the surprise of a government official who sent us the seed for conservation, as they were assured by a local grower that it would be “impossible” to germinate! Similarly, Bletilla striata grows very nicely on Western and P668/P668+B852 formulae. For particularly tricky species, it would be good to try relatively dilute media that do not use sucrose (i.e., Western media) first, with P668/P668+B852 as a backup. In fact, we sow just about everything that comes in the door (not just temperate species) on W2.5 + coconut and P668+B852. This combination is just about unbeatable- if it’s going to germinate at all (unless it’s REALLY weird), it’ll come up on one or the other or both. It’s an orthogonal combination- two media that are very dissimilar, but work very well for germination.

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