Why is armeniacum such a huge pain?

[kentuckiense]

Well, it is for me, anyway.

My armeniacum has slowly been shedding leaves. It is now down to two leaves and I have come to accept the fact that it is going to die. Is there a trick to these things? I grow almost all the other Parvisepalums and, if I do say so myself, I think they like (or tolerate) my conditions. I have no trouble with micranthum (including var. eburneum), malipoense, emersonii, delenatii, and I've even bloomed my vietnamense as well as numerous parvi primaries. I even have trouble with some armeniacum hybrids! I've killed an Armeni White (who does that?!), and my Wössner Vietnam Gold and Fumi's Delight have also been doing the leaf-shedding thing, albeit a bit more slowly than the species.

From looking at the extremely narrow geographic range of armeniacum, I would have to guess that they have fairly narrow ecological requirements and thus the problems with cultivation.

Growing in a standard bark mix about 8 inches under T8 shoplights. Relative humidity is somewhat low, but not bone dry, and I mist all my plants at least 4 times daily. Once summer rolls around, I'm considering picking up a larger plant and trying the basket technique. Any other advice?

 

[NYEric]

Move it further from the light and give more water.

 

[John M]

Is there a trick to these things?Yes.
Growing in a standard bark mix about 8 inches under T8 shoplights. Repot in 50% limestone gravel and 50% your bark mix. Use GroLux Wide Spectrum bulbs mixed with your cool white bulbs. One GLWS to one, two or three cool white is good.Relative humidity is somewhat low, but not bone dry, and I mist all my plants at least 4 times daily. Misting is a temporary solution to a permanent problem. You get to feel that you are doing something to help; but, if your humidity is low, you're not really helping at all. In dry conditions, after you mist, the air is humid for maybe 10 minutes. Better to place the plant inside an open topped, wide mouth glass jar or small aquarium. You want the top completely open to prevent any heat build up and too much humidity; but, the glass sides and bottom will create and hold a microclimate of humidity around the plant. Keep a tiny bit of water in the bottom with the pot above that. After you repot, water thoroughly and then feed with a transplant fert a couple times, a week apart @ 1/4 strength.
I use 10-52-10. Good luck! QUOTE]

 

[SlipperKing]

I really think John is onto something here when he suggest a 50/50% mix.
I lost every armeniacum I ever had in a bark/sponage rock/charcoal mix. Now my plants are doing a 180 degree flip with the same mix in a basket plus I added crushed oyster shell in the mix and as a top dressing. I grow in a GH so I can't give advice for lighting or the humidy aspect of it. The plants definitely like a drier period time in the root zone. That probably why they put out such long stolens.

 

[dan_t]

All the armeniacums I've got are in fine bark/perlite mix in a basket, but the bottom third of the basket is taken up by limestone chippings. I started to do this having read Cribb's paper on its habitat, and it seems to be doing great, so far... I give it plenty of water in the summer, dry and cool in the winter, much like some Dendrobs.

Dan

 

[SlipperKing]

Good points Dan on seasonal changes of water and temp

 

[Rick]

Both John and Dan have good points.

I have always used limestone gravel in the bottom of my parvi pots (except delenatii), and I supplement the mix with oyster shell too. And in the last year I've started using allot of bone meal as a top dressing.

I beleive it was Sanderianum that had some field observations of soil pH around armenicums, and said that the pH was generally above 7 in the younger active growth areas and low around old bloomed out growths that were dying back. Bark mixes start out at pH's less than neutral, and drop to as low as 4 in a fairly short time.

There are several implications to low pH, one of which is the availability of phosphorus drops dramatically below the low 6's, and without p available your plants may be eating themselves up for it even if you are adding it with a fertilzer mix. You'll notice that John's fertilizer choice is a high P bloom booster type. Also limestone rock has a fair amount of P in it, and oyster shell is a P sponge that the plants can access long term.

The humidity bit that John mentioned I think is also very important, and before I started regulating air humidity 24/7, I also saw allot of leaf drop in my paphs in general. The parvis aren't nearly as picky as the barbata, but I say that armenicum would still appreciate a pretty constant 60%.

 

[GaryB]

I think you will get improvement with higher humidity and higher light. In their natural environment, humidity in 80% in the summer and 60% in the winter. Armeniacum do well with 1800 - 2500 fc. Also, cooler night temperatures in the winter (50s) help set buds.

 

[Corbin]

I beleive it was Sanderianum that had some field observations of soil pH around armenicums, and said that the pH was generally above 7 in the younger active growth areas and low around old bloomed out growths that were dying back. Bark mixes start out at pH's less than neutral, and drop to as low as 4 in a fairly short time.

There are several implications to low pH, one of which is the availability of phosphorus drops dramatically below the low 6's, and without p available your plants may be eating themselves up for it even if you are adding it with a fertilzer mix. You'll notice that John's fertilizer choice is a high P bloom booster type. Also limestone rock has a fair amount of P in it, and oyster shell is a P sponge that the plants can access long term.

How do you measure the pH of the bark mix?

 

[Rick]

How do you measure the pH of the bark mix?

You could try soaking the pot in DI water for a half hour and see what the pH of the residual water ends up. There are also soil pH meters, but I'm not sure how effective they are in mixes that are real open (like a bark mix). Most of the soil probes I've seen like good contact between the soil and the probe.

This is a good question Ed. There was an article in Orchid magazine a few years back that tracked mix pH, and it might be good to see if we can pull a protocol out of that. My old man memory seems to recal a pore water approach.

 

[Corbin]

Come to think of it, I have an article, maybe the same one you are thinking about, at the apartment that discuss this. I'll look it up and report back.

 

[jblanford]

Where does one find limestone gravel?. Jim.

 

[NYEric]

Yeah I was wondering the same thing, there seems to be a problem in NYC getting some of the materials listed here!

 

[SlipperKing]

Yeah I was wondering the same thing, there seems to be a problem in NYC getting some of the materials listed here!

Eric, aren't you in the transportation business? Surely you have a friend or two that can get you a dump truck load

 

[NYEric]

I can get quarry material all the time; but how do I know what it is?

 

[SlipperKing]

Google and read the lingo...something about soft vs hard granite like

 

[NYEric]

When's the last time anybody got hit in the head w/ a 'soft' stone!?

 

[Jim Toomey]

Marine fish pet stores sell limestone gravel for salt water tanks.
Just rinse real well!
AHAB

 

[Rick]

Much of the SE is on Karst limestone. If it wasn't so heavy I could send you tons of limestone sand and gravel from a local quarry for cheap.

Maybe I need to start a new business.:wink:

Use of oyster shell is a really good start though:wink::wink:

 

[Eric Muehlbauer]

How about marble chips? I've seen them sold as a topping for potted plants...they are usually about 1-2 cm in diameter. Or the crushed coral sold in pet shops?