Media Preparation


Phalaenopsis Replate Media Preparation Instructions               (For One Litre)

You will need these ingredients

·         25grams Sigma 6668 Orchid Maintenance Media                                         5 grams white granulated sugar

·         1 litre Distilled water                                                                                      7 grams agar

·         One medium sized banana (not too ripe, with still a little green showing)

·         One medium sized baked potato in microwave

This is a gram scale with 25 grams of Sigma 6668 Orchid Maintenance Media on the tray.  Next you would set the scale to 30 grams, and then add enough white sugar to make the scale balance again. (5 grams of sugar). 










This shows the sugar added to the tray on the scale.  Once the 5 grams of sugar is added, set the scale to 37 grams, and then add enough agar to make the scale balance again. (7 grams of agar)




 This shows the agar added to the tray on top of the media and sugar.









Next you will need to prepare the water.  Pour 1 litre of distilled water into the kettle and turn it on.




Into the electric blender put ½ of a not too ripe, (a few spots is OK), medium sized banana, 1/3 of a medium baked potato, and the weighed media ingredients.  The potato is done in the microwave, and then scooped out with a spoon.  Banana and potato amounts are not too critical.  I used to weigh them as 75 grams of potato and 30 grams of banana, but I don’t do that anymore. (Doesn’t seem to matter enough to worry about)









When the kettle boils, add the boiling water slowly to the blender and put the lid on.  The volume should now be about 1.25± litres.  Wait for a minute or two before pulsing the blender, otherwise steam will be generated, and the whole thing will tend to boil over!!  Pulse the blender for a fraction of a second a few times to start the mixing process.  When safe, blend the mix thoroughly for at least a full two minutes until everything is completely mixed together and the bananas have emulsified.









This is what the final blended media looks like.  It is still near boiling temperature, so be careful!

I do not adjust the pH of the media.  I believe that the 6668 is sufficiently buffered.



Pour the hot media approx 25mm deep into clean rinsed flasks.  I am currently using the poly ones from Sigma because I have about 1000 of them.  The glass Erlenmeyer style of flask grows the best plants that I have seen, but the poly ones work just fine for me.  Once the flasks are filled, set the lid on them to reduce evaporation of the liquid.







This is what the flasks look like prior to autoclaving.  I use the Nexcare Band-Aids for a vent cover over a 1.5 mm round hole, which is covered with a Teflon micropore filter.  In a vented flask a small amount of gas exchanges when the flask is heated and cooled underneath the lights.  The Co2 entering the flask through the vent is enough for the plants to fix carbon from.  I have found that plants usually can be left longer in a vented flask than a non vented flask.  Also the seedlings seem to be able to transition quicker to a community pot when grown in a vented flask.
























The flasks with media are then put into the pressure cooker with the lids resting on the top, not snapped tight.  This is only for poly flasks, as they would implode slightly when taken out if the lid was tight.  Autoclave the flasks at 15lbs pressure for 15 minutes.



Once the flasks are cooked, they are removed from the autoclave carefully so as not to move the lids.  Place them onto a towel and place a towel over the top of them.  Allow them to cool for about one hour, and before removing the towel from the top, press on the top of the towel snapping the lids down.  Once completely cooled and the media has gelled, the edge of the lid is covered with cling film.




The edges of the lid are covered with 3 layers of cling wrap stretched tight. The last little bit is left sticking up vertically which makes it easy to grab the film once in the cabinet.

 I cut the full rolls into 50±mm pieces with power mitre saw.  This is tricky, and takes considerable strength to hold them down.  Take care!!

I used to leave them for a week to check for contamination, but I have nearly zero contamination recently, and now I will use the flasks the next day after making them.