Phragmipedium DLI light level.

[gonewild]

I'm interested to hear what DLI (Daily Light Integral) phrags grow best with.

Would light to hear about actual experience for Phrags not based on a general light requirement table for moderate light levels.

 

[terryros]

I have grown Pharagmipediums for about 15 years, the last 13 under LED lights. I have decreased my Phrags over the years as I increased Cattleyas. I currently have only two plants of a tetraploid Jason Fischer, two plants of a triploid Fritz Schomburg, a seedling of a diploid Robert-Jan Quene, two plants of a triploid Yoko W. Fischer, one plant of schlimii/fischeri, and a kovachii seedling. My experience is heavily concentrated on hybrids of the species besseae and kovachii.

Besseae and kovachii are native at a latitude about 6 degrees south of the equator. This location has a 12.4-hour mid-summer day length and an 11.7-hour mid-winter day length. I do not have a separate growing area for Phragmipediums, so they receive the 11.5 to 13.0-hour yearly day length variation that all my plants receive.

The natural change in the sun's angle from mid-summer to mid-winter in the besseae/kovachii latitude results in a modest 10% change in light intensity.

However, I do not vary the light intensity for my Phragmipediums to compensate for the modest excessive day length variation and keep a steadier daily light integral (DLI).

In the August 2021 AOS journal, Kelly McCracken reported results using LED lighting in her commercial grow houses in Arizona. She used the Apogee 500 light meter (which I also use) to measure light intensity as peak photon flux density (PPFD) in the photosynthetically active range (PAR). She noted that a constant PPFD of 150 micromoles/meter squared/second (probably at the mid-leaf zone) and a steady 12-hour day length throughout the year was successful with Phragmipediums. This would be a daily light integral (DLI) of 6.5.

My Phragmipediums receive a steady 125 PPFD throughout my varying day length year, resulting in a yearly average DLI of 5.75. My plants grow and bloom well. My two Jason Fischer and my schlimii/fischeri plants are now blooming. A Fritz Schomburg and Yoko W. Fischer are in spike and the other two plants of these hybrids recently finished flowering. My kovachii and Robert-Jan Quene still need to reach blooming size.

My plants might grow better if I modestly increased the DLI by lowering my lights several inches. However, I avoid this because, with my current LED fixture, headroom for spikes would be modestly compromised.

A steady 12-hour day and 100-150 PPFD should accommodate excellent Phragmipedium growth and flowering, at least with besseae, kovachii, and hybrids.

 

[gonewild]

Thanks for the detailed explanation! That's exactly what I wanted to know.
I don't have an Apogee meter to measure with. I've used an FC meter and the mathematical formula to convert. And recently the Photone phone app. Both give similar results. Have you by any chance compared your Apogee to the Photone so as to know the potential margin of error?

 

[terryros]

I have not. I think an important issue is measuring the photons in the PAR range. I don’t think most FC meters and phone apps will not be filtering to the PAR range. For some light sources you will be measuring light intensity falsely high. I know the Apogee meters are relatively expensive, but I decided that the cost (money and time) of growing expensive plants with incorrect light intensity were worth buying the meter. I always thought that a group of growers (even an orchid society) could pool money and buy one that they share.

 

[southernbelle]

Thanks for the detailed explanation! That's exactly what I wanted to know.
I don't have an Apogee meter to measure with. I've used an FC meter and the mathematical formula to convert. And recently the Photone phone app. Both give similar results. Have you by any chance compared your Apogee to the Photone so as to know the potential margin of error?

Be sure your Apogee meter measures what you want it to. Only the upper level ones measure the spectrum of LEDs. I has a lower level one that measured 20% low.

 

[southernbelle]

I have grown Pharagmipediums for about 15 years, the last 13 under LED lights. I have decreased my Phrags over the years as I increased Cattleyas. I currently have only two plants of a tetraploid Jason Fischer, two plants of a triploid Fritz Schomburg, a seedling of a diploid Robert-Jan Quene, two plants of a triploid Yoko W. Fischer, one plant of schlimii/fischeri, and a kovachii seedling. My experience is heavily concentrated on hybrids of the species besseae and kovachii.

Besseae and kovachii are native at a latitude about 6 degrees south of the equator. This location has a 12.4-hour mid-summer day length and an 11.7-hour mid-winter day length. I do not have a separate growing area for Phragmipediums, so they receive the 11.5 to 13.0-hour yearly day length variation that all my plants receive.

The natural change in the sun's angle from mid-summer to mid-winter in the besseae/kovachii latitude results in a modest 10% change in light intensity.

However, I do not vary the light intensity for my Phragmipediums to compensate for the modest excessive day length variation and keep a steadier daily light integral (DLI).

In the August 2021 AOS journal, Kelly McCracken reported results using LED lighting in her commercial grow houses in Arizona. She used the Apogee 500 light meter (which I also use) to measure light intensity as peak photon flux density (PPFD) in the photosynthetically active range (PAR). She noted that a constant PPFD of 150 micromoles/meter squared/second (probably at the mid-leaf zone) and a steady 12-hour day length throughout the year was successful with Phragmipediums. This would be a daily light integral (DLI) of 6.5.

My Phragmipediums receive a steady 125 PPFD throughout my varying day length year, resulting in a yearly average DLI of 5.75. My plants grow and bloom well. My two Jason Fischer and my schlimii/fischeri plants are now blooming. A Fritz Schomburg and Yoko W. Fischer are in spike and the other two plants of these hybrids recently finished flowering. My kovachii and Robert-Jan Quene still need to reach blooming size.

My plants might grow better if I modestly increased the DLI by lowering my lights several inches. However, I avoid this because, with my current LED fixture, headroom for spikes would be modestly compromised.

A steady 12-hour day and 100-150 PPFD should accommodate excellent Phragmipedium growth and flowering, at least with besseae, kovachii, and hybrids.

I’d love to see the Jason Fischers and others.
I’ve just revisited Kelly McKracken’s info on PAR and have increased the light on phrags and miltoniopsis. We shall see…

 

[terryros]

Be sure your Apogee meter measures what you want it to. Only the upper level ones measure the spectrum of LEDs. I has a lower level one that measured 20% low.

Deborah, that was an older version that we had. All the new 500 series now accurately measure within the PAR range.

 

[southernbelle]

Deborah, that was an older version that we had. All the new 500 series now accurately measure within the PAR range.

I know, but somehow when I got my new one I got a MQ 510 by mistake. It is designed with an adjustment for the refraction of measuring through water for use in aquariums. So not accurate for my use. I just ordered the DLI 600 and will sell the 510 on eBay. The new 600 measures ePAR and automatically logs the DLI if you run it all the time.

 

[terryros]

I know, but somehow when I got my new one I got a MQ 510 by mistake. It is designed with an adjustment for the refraction of measuring through water for use in aquariums. So not accurate for my use. I just ordered the DLI 600 and will sell the 510 on eBay. The new 600 measures ePAR and automatically logs the DLI if you run it all the time.

Sorry, I didn’t know that. The automatic DLI part is very useful the natural light (including green house grower) where the light intensity changes greatly throughout a day. The constant change in day length is also being measured. With LED lighting, the intensity is constant and the calculation of DLI is an easy one. Maybe I will post a grid that shows the DLI for different day lengths and light intensity.

 

[terryros]

A simple table shows the DLI achieved with various light intensities (peak photon flux density, PPFD) and two different day lengths. DLI is moles of photons per day.

 

[FrankRC]

You are seriously overthinking this. Two reasons. First, besseae is highly adaptable to light levels. In nature, plants grow in exposed locations and under a heavy a canopy of surrounding plants and all produce flowers and show very happy plants. Don’t sweat light levels with besseae and its primary hybrids. This is one of the reasons you see so many besseae hybrids. They adapt well to northern and changing light levels. Second, kovachii likes bright light year round, but no direct sunlight. While there are some growers with spectacular plants in northern latitudes, the vast majority of kovachii plants rot and die this far north. That species needs supplemental light in the winter for greenhouse growers up here. If your hybrids have besseae in them, don’t over think this so much. It’s really not necessary.

Best,

 

[southernbelle]

Sorry, I didn’t know that. The automatic DLI part is very useful the natural light (including green house grower) where the light intensity changes greatly throughout a day. The constant change in day length is also being measured. With LED lighting, the intensity is constant and the calculation of DLI is an easy one. Maybe I will post a grid that shows the DLI for different day lengths and light intensity.

I just realized recently that I’d gotten the wrong one. I was interested that now they say ‘extended PAR’. The spectral range of PAR (what plants use) has been extended it seems. This meter measures the ePAR and as an aside came with the DLI feature. I like it because it doesn’t have a separate light sensor on a cord. The sensor is integral like the first one I had.

 

[Nelson Wong]

I grow my Phrags with my Multifloral paphs. 150 to 200 PPFD 10 to 13hrs a day.

I have had consistent blooming in my multifloral Paphs.

For the Phrag, I have been EXTREMELY unsuccessful with blooming them, despite constant watering and fertilization (20-20-20). While they grow ENORMOUS leaves around 1.5 feet to 2 feet long vibrant, green leaves, new growths (around 2 mature growths each year) and root system that wraps around my 5 and 6 inch pot within 6 months. I was told by multiple other nursery and growers that Phrags can take higher amount of nutrients of Paphs. To bloom they need temperature change and extremely high amount of phosphorous, potassium, calcium and magnesium) So I have increase phrag fertilization/ watering to (27-64-29), We will see if the coming fall weather outside will trigger blooms anytime soon.

For my paphs I fertilize/water the same 27-67-29, but just about 30% more diluted.

p.s. all my fertilizer is measured in approximately 1 liter. Paphs 0.5g (20-20-20) + 0.2g (7-47-9) over 1L. Phrag 0.6g (20-20-20) + 0.3g (7-47-9) over 1L. I do a wash with 0.2g + 0.1g once every other week or once a month.

 

[gonewild]

Back on PAR....
Obviously not assuming the Photone home app would be accurate I considered ordering an Apogee from Amazon. I spotted a less expensive PAR meter and checked reviews online. I found several side by side comparisons on a few cannabis forums. Some said it measured the same as the Apogee and some said it varied about 2%.
The wavelengths are measured in the 400-700 range
I ordered one cost $85.


To test it my lights measured 159.9 ppfd.
Measuring with the Photone app gave a reading of 178 ppfd. So the Photone shows more 12% more light, which is misleading.
I think the this Danoplus should be accurate enough.

 

[terryros]

It seems to be measuring the correct thing. It doesn’t have to be perfectly accurate to guide you so it may work for you. I wish you could compare it to the Apogee for 15 minutes and you would know.