The Orchid Seedbank Project
PO Box 7042
Chandler, AZ 85246

Sowing Orchid Seeds on Nutrient Media

I get a lot of questions about how to grow orchids from seed. First off, there are two steps: Mother flask, and replate flask.

Mother flasks are used to germinate the orchid seed. The reason is simple: There are chemicals that inhibit germination that are present in replate media. The compounds that help the young plants grow keep them from germinating. In most media, banana is used to grow plants quickly; there is some evidence that banana will inhibit germination of SOME orchids. Unfortunately, there is no way to distinguish those that are inhibited from those that aren't without testing.

The easiest way to propagate relatively large numbers of seedlings very quickly is to use small flasks for germination. You can still use pint or quart jars, or other such flasks, but we find it convenient to use baby food jars. Keep the lids.

For seed germination, we use P-6668 (Sigma) or P-668 (PhytoTech). They are equivalent. The media is inexpensive, reliable, and works for a diverse range of tropical epiphytic orchids- but has also worked for some temperate species, and sometimes for terrestrial or littoral species. The media does not come with agar; you will need to add agar "to flavor." Since it makes it easier to pluck the protocorms from the surface, from 8.5 to 9.0 grams of agar (or even more, if so desired) may be used per liter of mix.

About 30 baby food jars with 30 ml of solution each may be prepared from one liter of mother flask. At $2 per liter of formula, this works out to less than 7 cents per mother flask. Line up the bottles, and prepare the media by adding about 800 ml of distilled water to a flask. Heat the water; when it is steaming hot, add the agar and dissolve it. Make certain there are no clumps. Add the media, stirring briskly. In fact, a magnetic stir plate is the best way to prepare media; we strongly recommend one if you are going to prepare media regularly. Make sure all clumps are broken up and dissolved before pouring.

While hot, pour the media into baby food jars. Swirl the flask between jars, keeping the media homogeneous. The lids should be loose enough that they may vent gas when in the autoclave. Do NOT seal them tightly! Place in autoclave or pressure cooker for 10-15 minutes at 15 psig.

When cool, remove from the autoclave and tighten the lids down with a clean cloth. Number each jar for future reference using a "Sharpie" or other water-resistant marker. Place in glove  box or sterile flow workspace.

Seed is then disinfected, using the techniques outlined elsewhere. Be certain to carefully log which species goes into which flask.

Flasks are placed on a wire rack shelf at 20-25 degrees C, about 4 feet away from a brightly lit window (sorry to be so unscientific). They are examined at least 2x a week for growth. At the first sign of protocorms, the flasks are placed under brighter light: 12" under twin, 40-watt fluorescent tubes.

Depending upon how tolerant the plants are, they may require replate within days, or within months of germination. Best to replate too soon than too late.

Disclaimer: if anything I suggest is illegal, or falls outside the labeling on the products, don't do it. I'm not responsible if you put your eye out.


[OSP] [Technical Data]

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The Orchid Seedbank Project
PO Box 7042
Chandler, AZ 85246