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Discussion in 'Beginner Zone' started by Phred, May 30, 2019.
Elongated growth... Can anyone tell me why Paphiopedilum grow like this sometimes.
Are you growing under lights? What type of lights?
I do grow under lights. They are SunBlaster T5 - 54 watt high output bulbs with reflectors.
I would suspect insufficient light.
How many bulbs, covering what area? How far above the plants? How old are the bulbs?
There is one 4’ bulb over each shelf which is about 18” wide. The lights are about 8-10” above the plants. They were burning some of the plants so I have them shaded. I leave them on for 10-12 hours.
I'd suspect to less light, too. I grow under two 36 watt each 120 cm bulbs (T8) on shelves of 30cm. They are on for 15 hours a day, additional to daylight from the window. I use fluora, these are optimized for the demands of plants.
I never had the impression that it is too much light.
The Maudiae types sometimes tend to have elongated growth.
BTW your setup is very impressive!
Following in order to learn. Your grow is staggering to me. I grow in windows and I’m limited in terms of space...if I had a room like yours....
I don't think too little light is the reason. The reason does not matter. You will have to re-pot to address the stolonous growth. Nice, neat growing area; thanks for sharing.
Your growing area is very impressive. Inspirational, even.
Download a lux meter onto your phone (I assume you have smart phone, otherwise grab a teenager) and measure the lux. You can estimate about 20 PPFD per 1000 lux. I think Ray or Naoki was suggesting 100 PPFD is fine for our Paphs. The spectrum might be the issue rather than light volume. Too much far-red relative to red and blue light can cause stem elongation. Your shading devices might be filtering out the blue and red and letting too much far red pass?
When I was growing under lights my main bench had four 8' T12 HO bulbs. That was over a 8' x 30in. wide bench at approx. the same distance above the plants as you're discussing and I never had a problem with leaf burn. I also had a two ft. box fan that circulated the air whenever the lights were on. Could the yellowing of the leaves be related to heat rather than too much light? By the way, the lights were on 14hr/day, shortened to 12 in the winter.
The light meter suggestion is a good one. I'll bet your shade has cut the light intensity far more than it appears to the human eye.
I agree that the spectrum might be an issue.
Also you probably would be ok to extend the light interval to 14hrs. I've been growing my plants under 20hrs with no problems aside from the electricity bill (I since stopped).
Plants (in general) tend to have that elongated growth when crowded together or perceive competition from neighboring plants. Your set up doesn't appear to be too crowded but it might help spreading the pots out more, if space allows it.
Also, I'm assuming you haven't been applying any pesticides/chemicals? Some contain growth hormones that might cause similar symptoms.
True enough. If you use a growth stimulant that contains predominately cytokinins (kelp extracts made from Ascophyllum nodosum fall into this category), they will stimulate plant growth first, which in turn stimulates root growth. If the conditions are a bit awry, that plant growth can end up being leggy.
I doubt the spectrum is the issue. Yes, the plant needs light in the PAR (400-700 nm) range of the spectrum, but unless the light is really skewed to either end of that range, it's probably OK. White light is actually reasonably good about that.
Biologically, plants must have a certain "volume" of light, the intensity x time, both of which can be adjusted - within reason - to compensate for a change in the other. Each plant has its own range of volume needed to grow and bloom well. Too little of too much can be a negative.
I agree with what you say about light volume.
However I have reasons to suspect the spectrum could be a factor. In onions (bulb=modified stem, also a monocots), we seen bulb shape greatly affected by light intensity. If you plant an onion by itself and it receives high light intensity of full spectrum wavelengths it will have the tendency to flatten out, whereas in high density plantings under low light intensity with a modified spectrum of light the shape is elongated. Plants "perceive" crowding through the leaf canopy light reflection, ie the light being reflected off another leaf which is a specific ratio of more wavelengths of one over the other.
Of course, this is onion, not orchids, but there may be some relationship.
You changed three things: planting density, light level, and spectrum. How can you possibly know that it was the spectrum that affected the bulb shape?
Passing through a forest canopy, light intensity is diminished and the spectrum changes to having more green in it, due to leaf absorption and reflection properties. In Phred's case, the shading is white, so should have very little influence on the spectrum.
This the 2700k or the 6400k model?
Well we know from several scientific studies. We also know from other studies the effects of blue, red, and far red ratios on plant growth.
But, what you say about the white shading is correct. However the light source doesn't account for the reflected light coming off the neighboring plants.
I don't think light intensity is not a factor here, however, I wouldn't outright dismiss the spectrum influences.
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