Orchid Flasking

Growing Orchids by John Marvin

Orchid flasking is a procedure in which orchids can be grown from seeds, and is necessary for producing orchid seedlings, since orchid seeds do not have an endosperm and usually require a symbiotic mycorrhizal fungus to germinate.

There are two different techniques for flasking: symbiotic germination and asymbiotic germination. Symbiotic germination requires the isolation of a mycorrhizal fungus which is added to the agar in which the seeds are grown. Asymbiotic germination just uses the nutrients that the seed requires to grow.


  1. Sterile environment: An environment without fungal spores such as a glove box or over steaming water.
  2. Seed pods
  3. The Flask can be any glass bottle
  4. Cap (if using a cap, tape the sides of the container with waterproof bandages or aluminum foil) for flask or rubber stopper (must have a hole in the top which is stuffed with cotton)
  5. Stainless steel rod bent into a hoop at the end
  6. Spray bottle set to 'mist'
  7. Medium (What seeds are planted on)
  8. Sterilizing agent: Bleach, sodium hypochlorite, or ethanol/isopropanol alcohol can be used.


Preparing the flaskEdit

For flasking, all materials must be sterilized first. This is done using a pressure cooker.

  1. First prepare the medium inside a flask. Make sure it is at least 25 mm (about 1 inch) deep. If you are planning to sow the seeds and re-plant into another flask, use 13 mm of medium (about ½ inch) Do not be tempted to make a thinner layer of medium.
  2. Put the lid on the flask and place the flask in the pressure cooker. Pour about 2 inches of water into the cooker and cook the flask for 15 minutes @ 15 psi. A microwave can also be used instead of a pressure cooker, but a dish of water must be added under the flask so it does not boil over.
  3. Place all tools (knife, bleach, container of water) and the flask inside a glove box. Spray the glove box with a mist of 10% bleach solution all over the inside of the case and wait five minutes for the solution to kill all the contaminants.

Seed sowingEdit

Once the flask are prepared, the seeds can be sown in two different ways. They can take from several months to several years to germinate.

Green-pod methodEdit

The green-pod method is a method of sowing orchid seeds before the seed pod is fully mature. Make sure the seed capsule is not broken.

  1. Put the seed capsule into the glove box. If you don't have a glove box, this can be done in area with steam such as over boiling water.
  2. Sterilize the seed capsule by washing it in a 5% bleach solution or a 1:4 solution of 60 - 70% sodium hypochlorite (NaClO) for at least 15 minutes. During the wash, scrub the outside of the capsule with a toothbrush.
  3. After washing it, rinse the seed capsule in distilled water.
  4. Cut open the seed pod with a sterile knife or spatula.
  5. Use the spatula or a steel rod with a ring to spread seeds over the medium. To eliminate fibrous material, seeds can also be washed out of the seedpod with distilled water and pipetted into the mix.
  6. Seal the flask.

Dry pod methodEdit

The dry pod method is used to sow dry seed or seed pods with cracks on them. It is best to sow as soon as possible after harvest. Seeds can be kept for several weeks, but they may gradually lose viability.

  1. Add the seeds to a 50-ml bottle
  2. Create and add 15 ml of a solution of 3.5 - 7 g of Calcium hypochlorite per 100 ml of water to the bottle and one drop of detergent
  3. Shake for 5 minutes and filter the solution with a funnel and filter paper
  4. Filter two more times with sterile water and move the bottle (with the filter paper covering it) and the funnel into the glove box.
  5. Open the flask and use a sterilized spatula (5% bleach solution or a 1:4 solution of 60 - 70% Sodium hypochlorite (NaClO) for at least 10 - 15 minutes) and spread the seeds from the filter paper onto the flask.
  6. Seal the flask.


If the medium dries out due to air exchange or the plants are getting overcrowded, you may want to consider transplanting the protocorms. Start by sterilizing the tools used in transplanting by leaving them in a container of 10% bleach solution for 5 - 10 minutes. Place the flask inside a glove box and mist the area with bleach.

Prepare one or more flasks with medium. Distilled water can be used to remove all protocorms from the flask. If just a few protocorms are desired to be transplanted, use a steel rod with a loop. When transplanting, leave sufficient space between protocorms.

Caring for flasksEdit

Orchid flasks should be kept under fluorescent lights for 8 hours per day. The flask must be kept in an area at 70 - 75 °F. Do not try to simulate daylight hours because it will stress the seeds. Seeds should normally begin to grow in four to six weeks, but some species can take up to a year to germinate. Some plants require different conditions to germinate, such as darkness (Paphiopedilum ciliolare).

If the flask is contaminated, it will usually show up in the first week. If this happens, it is best to discard all its contents and start again.


When the plants have more than three roots, you may de-flask them.

  1. Place the flask in warm water for five to ten minutes to melt the jelly.
  2. Open the jar and pour the seedlings out. Place the plants into a shallow dish of water and use a stick to carefully tease the jelly off the roots. If the flask has a narrow neck, the seedlings can be removed by rinsing the bottle with water.
  3. Prepare a tray with compost and moisten it with some water. Make several depressions in the tray and carefully place the plants in. Cover the roots of the plant. If any roots break, apply fungicide. Plants can also be grown in sphagnum moss. It is best not to fertilize them for two weeks.
  4. Keep the plants in 70% shade. Place a cover over the tray and slowly open it over a four-week period to allow the plants to adjust to the environment's humidity.

External LinksEdit

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