You could purchase a pre-made lighting system, but there is usually no way to automatically control the amount of light, choose the frequencies of light being used, or be able to adjust the location of the LEDs. Adjusting the light levels will be important in experimentation to see what the orchids like.
I opted to build a lighting system from scratch, especially after finding out how easy it was with instructions from ledgardener.
Components
- 4 CREE CXB3590 (3500K 80 CRI) 36 volt 1.2 ampere COB LEDs. These are full spectrum LEDs.
- Emerson Effect booster board. This has photo red LEDs in the 660NM light range, far red LEDs in 730NM. Both types of LEDs can be controlled independently with PWM signals. The Emerson Effect can be used to make the vanda orchids grow much faster (they are usually one of the slowest growing orchids). The far red LEDs can be left on for 15 minutes after sunset to promote flowering.
- Mean Well HLG-240H-C1400B LED driver. The 240 designates watts. This is a bit too much power, but the closest power level for four LEDs. This will result in the inability to dim the LEDs through the whole light intensity range. The 1.400 is the current in amps. The B is for adjusting the light intensity using Pulse Width Modulation (PWM).
- LED reflectors to focus the light downwards.
- 34″ canopy rail to mount the LEDs with heat sinks. These rails allow the LEDs to slide along and adjust where the light is placed.
- Thermal pads to make sure that heat is transferred from the LEDs to the heat sinks.
- Pin-style heat dissipation heat sinks
- One wire coat hanger, cut into four hooks to “secure” the rails to the the top of the orchidarium (I drilled four holes half-way into the top, and stuck the coat hangers in the hole and created a hook at the other end to attach the light canopy railing). The LED canopy is suspended above the polycarbonate top so that heat can escape from the reflectors. This is a temporary solution until I can make more solid brackets. So many uses for wire coat hangers! But probably the only place you can get them anymore is at a dry cleaners.
Light Spectrum
I choose full spectrum CREE 3500K 80 CRI LEDs so that the blue range at 450nm is high, but there is still a lot of red at 590nm. The Emerson board then boosts the photo red and far red.
Assembly
I wired the COB LEDs in series, so the total voltage is 144 volts. No soldering is necessary. I used wire cable clips to fix the LEDs in place on the rail so they don’t slide around.
Emerson Effect Board
For the emerson effect board I took thin aluminum sheet metal, cut it to the length of the board and bent it into this shape around the board. This will protect the LEDs from damage (yes, my first accident), and also focus the red light downwards.
The sheet metal also acts as a heat sink, although the LEDs do not get hot enough to require one.
Putting the booster board at the front of the orchidarium will help turn the flowers forward for better viewing. I found this out by accident, not by design. However the flower stalk likes to follow the main LED, so put the orchids as far back in the orchidarium as you can.
Unfortunately the booster board is so long that the LED drivers stick out to the side of the orchidarium. This makes adding crown molding on top difficult, but not impossible (for hiding the heatsinks and water tubing). It just means that the crown molding will have to be custom instead of the standard 45 degrees miter joint. I’ll leave that till last.
Light Levels
I run the main LEDs at 20 to 30 percent intensity. Anything more than that burns the leaves if left on all day. I have a control for sunrise and sunset that takes this mid-day level and ramps it up or down over the period of an hour. I will try ramping up to a higher level throughout the day. For vanda orchids, the way to tell if they are getting enough light is if the leaves are greenish yellow (not deep dark green like many other species of orchids). The red LEDs are run at 30 to 40 percent.
A problem with having a 36″ terrarium is that there is very little room for vanda orchids which require around 36″. The orchids end up being too close to the lights unless mounted as low as possible. Otherwise the radiant heat from the LEDs will wrinkle the flowers.
I also put a TSL2591 light sensor outside the orchidarium underneath the jungle backing print. This can be used to make sure that the LEDs are not fading or burnt out.