Is replating always necessary?

[escualida]

I'm thinking about flasking some seeds and have been reading a lot about it and I've seen a lot of people talk about replating and I was wondering if this was always necessary? Is it not feasible to flask the seeds and keep them in the original flask until they are big enough to deflask?

Thanks in advance for your answers!

[NatalieS]

It unfortunately is necessary for most orchids that I've looked into germinating from seed. The most important reasons to replate are:

• To ensure protocorms and seedlings have a continous supply of nutrients
• To reduce over crowding

Regarding the first point, most orchids generally take a couple of years to go from germination to the point where they can be deflasked and there's a finite amount of nutrients in your flasks. Your little plants will eventually use them all up and the only way to give them more is to put them on fresh media. By way of example, you probably fertilise your orchids regularly. You do this because there's no other way for your plant to get nutrients to grow if you grow in a closed environment (i.e. in pots or mounted in your home, or greenhouse) and not growing naturally on a tree in your garden say. Your plant tends to grow better and be more healthy when you do follow a fertilising schedule. It's the same for your baby orchids in their closed flasks.

Also, when you first flask your seeds, they are so tiny that you'll likely get hundreds of seed germinating in one flask. That's too much to grow happily to deflasking stage without competing for resources and weakening each other. When sowing any seed, even in your garden, they will always advise to thin them out once they've reached a certain stage. Thinning your seedlings out ensures more healthy plants.

[Ray]

I am also sure the particular plant makes a difference, too.

Holger Pernar mentioned that he must use a 4-stage replating process to get reasonable survival rate among Paphiopedilum tigrinum, for example.

[orchidsarefun]

there are probably a hundred reasons that would support the need for replating, but if you have the time and seeds I would say go for NOT replating as an experiment.
I have read ( and been advised ) that certain orchids, notably phals, produce a medium pollutant as a consequence of growth and just this fact requires a medium cleaning/change. So there are other reasons that may require you to open the flask.

[NatalieS]

Originally Posted by orchidsarefun

I have read ( and been advised ) that certain orchids, notably phals, produce a medium pollutant as a consequence of growth and just this fact requires a medium cleaning/change. So there are other reasons that may require you to open the flask.

Yes, that is also a good reason. It's why activated charcoal is often added to the media since the charcoal absorbs a lot of the pollutants made by the seedlings.

[escualida]

Got it, thanks! Does anyone have a good tutorial on how and when to replate?