Seedlings aren't thriving - why?

[OzPhal]

Hi Everybody,

I have some phal seedlings growing in a semi-hydroponic setup. I'm using perlite as the medium - a small fish tank as the reservoir. The lid is on the fish tank. There are holes in the side of the pots and about an inch of water in the bottom - to this i add Growth Technology Orchid Focus which has the following constituents (%w/v):

Nitrogen 1.29%
Phosphorous 0.31%
Potassium 1.01%
Calcium 1.00%
Magnesium 0.40%
Sulfate 0.15%
Iron 0.031%
Manganese 0.0095%
Boron 0.0021%
Zinc 0.0020%
Copper 0.0010%
Molybdenum 0.0005%

Humidity is around 75% with temperatures between 20 - 28oC. The unit sits in front of a south facing window (i'm in the southern hemisphere) and there is a small fan in there running on a continuous basis for air movement. I add fertiliser every few weeks (about 7ml per litre) and the reservoir holds about 4 litres...

Why are my little ladies not thriving? I've had them since i deflasked them in may last year... they have put out a few new leaves but that's about it... I have a phal bellina in there that just seems to have gone dormant

Any advice you could offer would be appreciated

[IMG][/IMG]

[Anisa]

Would southern window in southern hemisphere equals north window in northern hemisphere? I wonder if your seedlings get enough light. In your picture it looks like they are a couple feet away from non-light bearing window behind of curtain and protected by glass. Seedlings need bright indirect light. Maybe add a some light? Other than that it looks like you have a good set up.

[King_of_orchid_growing:)]

Why?

Has there been a large die off rate?

The ones in the pic don't look bad.

Have you pulled one of the larger ones out of the pot to see if the roots are still okay?

Seedling die off is usually related to how the roots and leaves are accustomed to living life in a jar. The roots may have died off with no new roots that have been accustomed to growing outside a jar taking their place.

Acclimation to a drier environment is important.

Another thing to try next time, is to do it during the spring with Phals. Phals grow slow, they acclimate slow, and they have a preferred growing season where they do most of their growing (mid to late spring). Deflasking during spring gives them a fighting chance to recover.

Is this your first batch of seedlings?

[King_of_orchid_growing:)]

Maybe instead of placing the pots in the water, try growing them the way they would be grown if they were adults, just with the humidity elevated and gradually taper off the moisture over time, idk.

[OzPhal]

Thanks for your reply mate, much appreciated. There has been a decent die off rate - i started out with about 64 seedlings originally. I haven't pulled any out of the pots to inspect the roots for fear it would do long term damage. They're growing new leaves nicely but to be honest i can't say i have seen any real new root growth above the potting medium.

What can i do to encourage these ones to grow roots/more vigorously?

Originally Posted by King_of_orchid_growing:)

Why?

Has there been a large die off rate?

The ones in the pic don't look bad.

Have you pulled one of the larger ones out of the pot to see if the roots are still okay?

Seedling die off is usually related to how the roots and leaves are accustomed to living life in a jar. The roots may have died off with no new roots that have been accustomed to growing outside a jar taking their place.

Acclimation to a drier environment is important.

Another thing to try next time, is to do it during the spring with Phals. Phals grow slow, they acclimate slow, and they have a preferred growing season where they do most of their growing (mid to late spring). Deflasking during spring gives them a fighting chance to recover.

Is this your first batch of seedlings?

[OzPhal]

Originally Posted by King_of_orchid_growing:)

Maybe instead of placing the pots in the water, try growing them the way they would be grown if they were adults, just with the humidity elevated and gradually taper off the moisture over time, idk.

Sorry, i missed this reply before i posted mine asking what i could do. So would you suggest maybe elevating the pots out of the water, still leaving a reservoir in there for the time being to keep the humidity up, but not giving them wet feet? and then over time moving them across to another potting media such as a bark/spag mix?

[camille1585]

Moving them out of S/H into bark/sphag might not be a good idea since the roots are adapted to wet conditions.

I'd never heard of perlite being used as an S/H medium. Could that perhaps be part of the problem?

One thing that helps stimulate new roots is placing a heat mat under the pots, but I don't see how you'd do that with your tank.

[King_of_orchid_growing:)]

I should've been clearer.

I didn't recommend growing in bark, sorry.

If you had gone the route of growing in bark initially, then fine, but you went with perlite instead, which may still be okay.

Perlite is mostly volcanic glass, and is for the most part fairly inert. It obviously has excellent moisture retention qualities, but it may not dry out evenly - this is something I'm not too sure about, and can't say anything specific.

However, yes, leave a reservoir in there, but just elevate the pots the seedlings are in. See if that'll make a difference over time.

Btw, a high rate of seedling mortality is fairly common after deflasking depending on what species of orchid you're dealing with. Don't fret, you still have some left.

[OzPhal]

Thanks Philip for your clarification... is there a media that maybe i should change to which would be better for the S/H? I'll have a shot at raising them a little and see how it goes...

Originally Posted by King_of_orchid_growing:)

I should've been clearer.

I didn't recommend growing in bark, sorry.

If you had gone the route of growing in bark initially, then fine, but you went with perlite instead, which may still be okay.

Perlite is mostly volcanic glass, and is for the most part fairly inert. It obviously has excellent moisture retention qualities, but it may not dry out evenly - this is something I'm not too sure about, and can't say anything specific.

However, yes, leave a reservoir in there, but just elevate the pots the seedlings are in. See if that'll make a difference over time.

Btw, a high rate of seedling mortality is fairly common after deflasking depending on what species of orchid you're dealing with. Don't fret, you still have some left.

[King_of_orchid_growing:)]

I've only tried growing seedlings in a medium with some (not completely all) S/H materials, just this one time because I ran out of seedling potting media.

I also have some in pumice, which is closer to what perlite is like.

For me, the ones in pumice are doing just as well as the ones in the mix with small bark chips, charcoal, large perlite chunks, and some LECA.

It's just watching how much moisture gets retained and adjusting accordingly.

I'm not really the go-to-guy for semi-hydroponics advice. I'm aware of it. I know some basics, but I'm not the "grand-pimp-daddy" of s/h technique, btw.

Anyways...

Unless you can find more things to tell us, or show us, there's not much anybody really knows about your plants in your particular situation - only you'd know best.

Unfortunately, there's just a time when you gotta put to use the advice you're given, and see what happens; or find a way to figure it out on your own.