- By Wolfgang H Bandisch
- Posted April 20, 2016
A Beginner's Guide to growing Orchids from Seed: Replating and Seedling Care
Assuming that you have flasked some seeds a couple of months ago, you will find that these have now grown and crowded the flask. They will continue to grow and eventually form tiny little leaves and tiny little roots. At this stage it is recommended to replate. This means that in order to give the little plants more space we will need to place a small number of each in a new flask. The procedure is quite easy to perform and we prepare our work as described before with the exception that we now use a slightly different medium, the replate medium. This will contain nutrients that promote the growth of leaves and roots. Replate media can be purchased ready mixed from a number of suppliers. For preparation follow the instruction of the supplier. I add the following ingredients to speed up growth of the seedlings (this is optional):
To make 1 liter (1000 ml) of medium add 150 ml coconut water from young coconuts, 200 ml banana puree from ripe bananas and 100 ml potato water from freshly boiled, unpeeled potatoes. Also recommended is the addition of 1 gram per liter of activated charcoal (if not included in the premixed medium).
Once your flasks are sterilized and cooled off and your cabinet sterilized you can commence work. You will need a pair of stainless steel forceps, a burner, a jar with bleach solution and your spray bottle.
Wear your gloves and sit in front of the laminar flow cabinet. Spray all bottles thoroughly with bleach solution. Open the motherflask and lie it on its side with the opening facing you. Open a new replate flask and hold it at an angle, again the opening facing you.
The forceps should have soaked in the jar with bleach solution for a while. Grab them and flame them in the open flame of the burner. Insert the forceps in the replate medium to cool off. Then grab a few seeds or a small plant from the motherflask and transfer them to the replate flask. Do not touch the sides of either flask. In the replate flask try and space the plants allowing for them to grow for at least another 6 months (often much longer) until they are ready to be taken out of the flask. An average of 25-30 plants would be more than enough for a flask the size of a jam jar.
When the replate flask is full, close it and thoroughly spray especially under the lid. Replace the forceps in the bleach solution and re-flame before opening another replate flask.
Replate flasks should again be stored in a dry place. The light intensity can be higher than for motherflasks and may speed growth.
Inspect your flasks regularly for contamination and growth progress. Some plants will grow slowly and others faster. Provided they are growing uniformly, growing leaves and most importantly roots, all is in order.
Write in your notebook the date of replating, the number of flasks replated and other details such as additives used.
In most cases the plants will have to remain in the flask for a period of not less than 8 - 10 months before they can be taken out.
Plants are ready for unflasking when they have several pairs of leaves and strong and healthy roots. They will by then have reached a height of about 3 inches or more. The medium is by then practically exhausted. It is a good idea to move those flasks that are ready to be unflasked to the same situation in your greenhouse where you will want to grow the seedlings a couple of months earlier. While still sheltered from pests and diseases the plants can acclimatize the light and temperature conditions and thus 'hardened' before they are taken out of the flask.
To unflask we prepare a dish with water and add a teaspoon of fungicide. An old newspaper will come handy to dry off the plants. Open the flask and carefully remove the plants, taking care that the roots are not damaged in the process. Place the plants in the dish and gently remove the remaining medium from in between the roots. Place plants on the newspaper and let them dry off over night. Place seedlings in a flat tray on insect screening and leave them for about one month. During that time they only need to be watered. Do not fertilize the seedlings during that time.
To ensure that the seedlings will grow nicely we have to prepare a seedling mix for them which will allow them to live in a somewhat sheltered environment until they are large and strong enough to fight for themselves. This is done in a community pot. Mix 4 parts of seedling bark with 1 part of Perlite and 1 part of sphagnum moss. Soak this mixture thoroughly for a couple of hours. Add half teaspoon of fertilizer per 10 liter mix. Soak some sphagnum moss on its own. Then fill a 10 cm plastic pot 2/3rds with the seedling mix and top it up with a layer of 2 cm thickness of sphagnum moss so that the top of the sphagnum moss is about 2-3 cm below the rim of the pot. Depending on the size of the seedlings with a pencil of your forefinger make little holes in the sphagnum moss and gently place seedlings inside. Pack the sphagnum moss around the seedling and repeat until the community pot is full. You can plant seedlings quite closely and should get 30-40 seedlings in a community pot. Place the community pots in a spot in your greenhouse or garden that is well lit without getting direct sunlight.
Seedlings need special care in the first few months. They are the favourite treat of caterpillars, grasshoppers and snails with their nice tender young leaves and the many months of waiting can easily be destroyed in a matter of hours. Weeds like this environment. They thrive in seedling mix and soon take over if left alone.
Seedlings will only need minute amounts of fertilizer in their first months. Fertilizer should be of high nitrogen content to stimulate plant growth.
Seedlings will remain in the community pot for another 12 months and can then be repotted separately in a mix which should perhaps be half seedling, half-adult plant mix until fully established. Before repotting ensure that the seedlings have developed strong roots as otherwise they will not survive.