Once upon a time, after wishing for more quality Paphiopedilum seedlings, we rubbed the magic eBay lantern, and a flask of Paphiopedilum fairrieanum arrived at our house. Not content with one wish, we kept wishing, and more flasks of Paphiopedilum species appeared in the coming year. One shelf of orchid seedlings became two shelves of orchid seedlings. Two shelves of orchid seedlings became three shelves of orchid seedlings …
In this article, I will introduce our orchid seedling growing area setup, and why we made the switch to using LED lights for growing our Paphiopedilum seedlings. We are very pleased that we did!
The debut of the “orchid seedling station”
We began our Paphiopedilum seedling project by converting one shelf of a three tier, vertical vegetable seedling shelving unit that my husband Paul used for garden starts. The seedling station, as we liked to call it, was located in his home office, which, quite conveniently, is the warmest room of our house.
With that feature, we were already off to a good start for creating a designated “orchid warm room” for recently deflasked seedlings. From my prior experience, and reflections from an orchid society talk by Brandon Tam about the Huntington Garden Paphiopedilum collection, it was impressed upon me that warmer, and more humid, conditions accelerate Paphiopedilum seedling growth.
The small office easily accommodated a small electric heater to bump the temperature up a few degrees at night, to 61-62F (16C), and a room humidifier maintains the humidity at 50-70%. We use an oscillating fan to circulate air in the room, plus small USB powered fans on ever shelf. During winter rainy periods, which are both very humid and cool, a tower fan runs 24 hours a day for additional air movement over the lower two shelves of the seedling station.
I initially placed the Paphiopedilum seedlings on seedling heat mats for extra warmth, but determined that it was easier and more consistent to simply use the electric heater a few hours a night. And, of course, other orchids moved into the room. The Phalaenopsis heard about the 62F (16C) nights and nearly came running.
T5 HO fluorescent lights for orchid seedlings
All of the seedling and blooming size orchid shelves were initially illuminated with T5 HO florescent fixtures, the carryover from the original vegetable seedling setup, and my small growing area for Phalaenopsis. As our endeavor grew, we started to observe some challenges with the T5 HO fluorescent fixtures.
We began deflasking our first orchid seedlings in the cooler part of the year. And, back then, there was only one shelf of Paphiopedilum seedlings. As months went on, it both grew warmer outside, and as more shelves (and lights) were used, it began to grow warmer inside. While the small size of the office was beneficial for maintaining humidity and warm temperatures in the cooler part of the year, it also accumulated heat more rapidly.
By early autumn, it was reaching into the mid 80s (30C) in the “warm room” in the afternoon, despite only being in the low 70s (22C) outside. We needed to cut the heat load in the room, and the fluorescent lights were the obvious target. My initial foray into LED grow lights for the mature Paphiopedilum and other warm growers in the room is detailed in another article on the ups and downs of converting T5 HO fluorescents to LED lights.
In summary, growing was so much improved with the LED conversion tubes for T5 HO fluorescent bulbs, that my attention soon turned to the Paphiopedilum seedlings. They shouldn’t be left out of the LED grow light benefits!
The benefits of LED grow lights for orchids
LED grow lights for orchids has become a bit of a passion of mine, after understanding — and observing — the benefits of full spectrum, white light LEDs over fluorescent lights. Look at the diagram below and you will see a dramatic difference in the light spectrum between fluorescent lights and full spectrum LED grow lights. Having sporadic wavelengths across the natural light spectrum (like the fluorescent lights) is very different than actually providing a continuous spectrum of “plant usable light,” known as photosynthetically active radiation (PAR).
In another article, I describe in detail new ways of understanding LED lights for orchid growing. Suffice to say, the quality (spectrum) and quantity (intensity and duration) are key to simulating an optimal indoor orchid growing environment.
I currently have six different manufacturers of LED light bulbs, strips, and panels in use, and my favorite after a few years of use is Active Grow. The root growth on all of the orchids that I have converted to the Active Grow LEDs has been outstanding. Within a few weeks of the LED conversion from T5 HO fluorescents, I noticed many new roots on the majority of plants (I use clear pots). Root growth has continued into the winter, and leaf color is vibrant.
All of the blooming size Paphiopedilum and Phalaenopsis have flowered, or are in spike, at their regular timing under the LED grow lights. Our Kefersteinia tolimensis and Angraecum didieri bloomed as well, with a few Dendrobium also beginning their first buds at this writing.
(Note: I did not receive any free products or compensation from any manufacturer as part of writing the articles on LED horticultural lighting. My views are from our own orchid growing experience. We’ve incurred our own time and expense in researching and trialing many LED lights for orchid growing.)
LED grow lights for the orchid seedling station
Back now to the orchid seedling station. With the impressive results from my initial first trials of growing blooming size Paphiopedilum under LED lights, I wanted to extend the light spectrum benefits to the seedling Paphiopedilum.
However, there was a stumbling block. My older Sun Blaster T5 HO fixtures did not work with any of the conversion LED tubes on the market. Sun Blaster is developing its own conversion LEDs, but they are higher intensity and 38W per bulb. For comparison, Active Grow LED conversion bulbs are 24W each, and a T5 HO fluorescent tube is 54W.
We were at a technology turning point. I wanted the proven and high quality spectrum of the Active Grow LEDs AND the energy and heat savings of a lower wattage unit. To my surprise, there was a solution: a non-ballasted fixture called the Propagation Luminaire by Active Grow. Effectively, it is two LED fluorescent conversion bulbs in a dedicated fixture that only uses 40W of electricity. A two bulb T5 HO florescent fixture uses 108W. Need I say more?
Yes, actually, there is another important detail about the Propagation Luminaire! I learned this from the owner of Active Grow, with whom I spoke after working out the T5 HO LED conversion issues with my Sun Blaster fixtures. The ballasts of T5 HO fluorescent light fixtures increase the wattage of each bulb by 4-6W when in use. This is a downside to using T5 HO conversion LED tubes: they are actually 24W + 4-6W when in use. Also, the ballast will very likely have a shorter life span than the LED conversion bulbs.
LED technology is evolving towards non-ballasted fixtures, but this has yet to be fully developed in horticultural lighting. The Active Grow two bulb fixture is an example of the new non-ballasted LED fixtures with notably lower energy usage. However, like similar LED strip lights, the LEDs in the two bulb Propagation Luminaire are not replaceable.
In the future, Active Grow will be making non-ballasted T5 LED units with replaceable LED bulbs — a much more environmentally sustainable and energy efficient solution. To date, they only have a 4 bulb, T8 HO LED non-ballasted light fixture available. It might be my next choice for a larger LED lighting fixture …
The difference: our orchid seedlings under LED grow lights
I noticed two immediate differences after replacing all three of my T5 HO fluorescent fixtures with the Active Grow LED light fixture. First, the temperature in the room dropped at least five degrees during the day. Second, the seedling pots did not dry out as quickly, an obvious result of reduced heat radiation from the LED grow lights compared to the fluorescent bulbs.
The reduction in surface drying will likely be as significant as the improved light spectrum for the seedlings, particularly the recently deflasked seedlings. The root system of most Paphiopedilum seedlings is relatively shallow. I’ve noted that many Paphiopedilum seedlings, particularly smaller ones, have horizontally structured roots coming out of flask. Until they develop longer, deeper roots, they are more susceptible drying out.
While I’ve noticed that all of the Paphiopedilum seedlings are vigorous and have good leaf color under the LED grow lights, the smallest seedlings appear stronger. And some seedlings that I did not think would survive seem to be starting to grow now. I have a high survival rate when deflasking, about 95% for all Paphiopedilum species I’ve deflasked (except Paphiopedilum adductum). Which means that there are many smaller seedlings in our care, and I am hoping that they will now have a greater chance of growing and reaching blooming size.
Summary: LED grow lights for orchid seedlings
While this article and my experience has emphasized the benefits of LED grow lights for Paphiopedilum seedlings, I see no reason that other genera would not thrive as well. Although lower intensity LED grow lights, like the conversion T5 HO tubes and strip lights, are ideally suited to lower light orchids, I am also having blooming success with species that have higher light requirements. Furthermore, higher light levels are generally not necessary for vegetative growth, or even beneficial for newly deflasked seedlings.
The bottom line is that light — whether natural or human-made — must be the right quality and quantity to support plant growth. Well designed LED light spectrum is enabling indoor orchid growing to have access to a quality of light comparable to natural sunshine. This is a remarkable new opportunity for orchid growing and all horticulture.