Stalled flower spike
 

I received a Phal Tetrapsis Coerulea some months ago. It arrived with a flower spike just starting to poke through, but soon aborted likely due to stress of shipping.

A few months later, another spike started emerging and unfortunately my dog knocked it over and broke the spike.

Some more time passes and a third spike starts to emerge, so clearly this plant is intent on blooming. The spike grew about 7 inches or so, but has now done nothing for probably 2 months. I had started using a generic bloom boosting fertilizer, and in this time it has grown 5 new roots and just started on a new leaf.

I looked at the fertilizer content this morning, and the NPK values are 15-30-15. With the growth of the new leaf and roots, would this indicate too much nitrogen in the fertilizer?

https://imgur.com/a/AwurMaG
Imgur: The magic of the Internet

Plants are going to direct growth into the areas that “make sense” for them at the time under the current conditions. They need to balance their energy inputs and outputs. I have a number of phals that are currently growing leaves, roots, and spikes all at the same time. I have others only growing leaves or only growing roots, and some that don’t show any visible signs of growth. All of my phals get the same 9-2-3 fertilizer year round and are in the same area so their growing conditions are the same.

The use of high phosphorus “bloom booster” fertilizers has been shown to be unnecessary and ineffective to trigger blooming (I think Ray has some info on his site about this), but some people continue to use them for various reasons. Dropping the nitrogen level may encourage blooming in some cases, but it’s really up to the plant.

If it’s growing, that’s a good sign. I’ll bloom when it’s ready if conditions are suitable.

First, Welcome!

Search for posts from Ray, he has addressed this. The takeaway seems to be that high levels of nitrogen may inhibit blooming. So if you lower the nitrogen (which, if you don't change the amounts of the other constituents, they rise proportionally) you may get better blooming. So it would not be "adding" phosphorus, but rather reducing nitrogen that did the trick. And this might be relevant for a commercial grower. But from a practical point of view, the real problem is likely to be over-fertilizing in the first place. Even heavy feeders like Cyms don't do better being bombarded. I just toss a healthy pinch or two of time-release fertilizer on my Cyms in the spring to give them a bit of extra while they are in rapid growth, and then treat them like everything else. And they bloom very well. And most orchids need/want much less fertilizer than Cyms, since they grow more slowly. The details of fertilizer in general don't make a lot of difference until you get all the rest of the cultural factors right. Orchids need a little bit of fertilizer, relatively frequently, but correct light intensity AND duration, watering, potting medium, air flow, temperature, diurnal temperature variation, etc are far more important for good results.

Phal speciosa and tetraspis are known to be among the most finicky and difficult to bloom species as the range of conditions they'll do well in is rather narrow. These are pretty much obligate warm growers and will not bloom if not kept warm. Many Phal species will do well very well in intermediate temps with max temps not much higher than 75F, but for some, like tetraspis, that just isn't warm enough and they do much better if kept over 80F.

A low of 66F is probably pushing it and 76F might not be warm enough during the day.


I have a Phal speciosa hybrid that does exactly the same as yours (despite getting the same food and conditions as all my other Phals), and I really should get a heat mat for it. My temps are ideal for it only about 2 months of the year... I was hoping that hybrid vigor would make it more temperature tolerant but that clearly wasn't the case...


Another point, some Phals do not bloom immediately on new spikes. I have a Phal lueddemanniana which only blooms from 1year+ spikes. The first year the spike looks like yours does, but I don't know if this is typical behavior for tetraspis. My other lueddemanniana behaves normally and blooms right away...

Neat! I wouldn't have thought waiting a year to bloom after expending energy to grow a spike would be a good adaptation strategy, but it must benefit some of them in their natural habitat somehow.

The temp gauge had just been reset, with the lights on during the day it actually gets up to 86 now. So hopefully that will be sufficient.

I didn’t realize Tetrapsis were so finicky when I made the purchase, I guess I’ll have to go down a google rabbit hole.

This is what I have been told by some Phal growers at least, when I was asking why my speciosa cross was never blooming! If you find more information, please do share!

I found this and thought it had quite a bit of excellent information.

https://youtu.be/b60uta78tSM