JANUARY 2011

PRINCIPLES OF LIGHTFOR

ORCHID GROWERS

STAN BETTER

LIGHT PRISMWHEN THE SUN’S RAYS HIT A PRISM

THE VISIBLE LIGHT SPECTRUM IS REVEALED

PRINCIPLES OF LIGHT• LIGHT CAN INFLUENCE ALL ASPECTS OF ORCHID

PLANT GROWTH AND FLOWERING.• LIGHT PROVIDES THE ENERGY FOR

PHOTOSYNTHESIS WHICH IS THE PLANT’S ABLILITY TO CONVERT CARBON DIOXIDE (CO2) AND WATER (H2O) INTO SUGARS AND OXYGEN (O2).

• LIGHT (AS STEVE HELBLING SAYS) IS “FOOD FOR ORCHIDS”.

LIGHT DURATION

• DURATION OF LIGHT IN A 24 HOUR PERIOD IS KNOWN AS DAYLENGTH OR PHOTOPERIOD.

• PHOTOPERIOD CHANGES THROUGHOUT THE YEAR.• MAGNITUDE OF CHANGE DEPENDS ON LATITUDE: AT

THE EQUATOR THE CHANGE IS LESS (ABOUT 40 MINUTES) FROM WINTER TO SUMMER. IN CINCINNATI (40 DEGREE NORTH LATITUDE) THE PHOTOPERIOD CHANGE IS ABOUT 7 HOURS (9 HOURS DAY LENGTH IN WINTER AND 16 HOURS DAY LENGTH IN SUMMER).

WHY IS DURATION IMPORTANT?

• PHOTOPERIODS ARE A CONSISTANT ENVIRONMENTAL PARAMETER WHEN GROWING ORCHIDS. YOU CAN PLAN HOW AND WHAT YOU WANT TO GROW BASED ON YOUR REGION.

• MANY ORCHIDS USE THE CHANGE IN PHOTOPERIOD AS A FACTOR IN SIGNALING THE INDUCEMENT OF FLOWERING.

HOW HAS THE ORCHID GROWER ADDRESSED LIGHT DURATION?

• ORCHID GROWERS HAVE MANIPULATED THE PHOTOPERIOD BY THE USE OF ARTIFICIAL LIGHT EITHER TO SUPPLEMENT NATURAL LIGHT OR AS THE SOLE LIGHT SOURCE AS IN BASEMENT GROWING.

• BY CONTROLLING THE AMOUNT OF LIGHT, BOTH IN INTENSITY AND DURATION, THE ORCHID GROWER CAN CONTROL THE AMOUNT OF FOOT CANDLES, COLOR, AND PHOTOPERIOD REQUIRED FOR A PARTICULAR ORCHID TO GROW AND THRIVE.

• SUNLIGHT (IN TOTAL OR IN PART) IS THE FIRST CHOICE FOR GROWING OPTIMALLY.

WHAT PHOTOPERIOD SHOULD YOU PROVIDE YOUR ORCHIDS?

• THERE IS NO ONE ANSWER. IT DEPENDS ON THE PARTICULAR ORCHID YOU ARE GROWING AND ITS CULTURAL REQUIREMENTS.

• CONTINUOUS ARTIFICIAL LIGHTING (24 HOUR) IS NOT RECOMMENDED FOR ORCHIDS. THEY REQUIRE AT LEAST A 6 HOUR DARK PERIOD AT EACH 24 HOUR INTERVAL.

LIGHT QUALITY

• LIGHT CONSISTS OF INDIVIDUAL PARTICLES OF ENERGY CALLED PHOTONS.

• EACH PHOTON WITHIN THE VISIBLE LIGHT SPECTRUM HAS THE POTENTIAL TO DRIVE PHOTOSYNTHESIS.

• LIGHT QUALITY REFERS TO THE SPECTRAL DISTRIBUTION OF LIGHT RAYS HITTING THE PLANT.

LIGHT QUALITY

• THE ENERGY OF EACH PHOTON IS DEPENDENT ON ITS WAVELENGTH. FOR EXAMPLE, RED LIGHT HAS A LONG WAVELENGTH BUT LESS ENERGY PER PHOTON; BLUE LIGHT HAS A SHORTER WAVELENGTH BUT MORE ENERGY PER PHOTON.

• APPROXIMATELY ONE HALF OF THE ENERGY OF THE SUN’S RAYS FALLS WITHIN THE PLANT’S ABILITY TO PRODUCE PHOTOSYNTHESIS. THIS OCCURS MAINLY IN THE VISIBLE SPECTRUM OF LIGHT. THE REMAINING AMOUNTS ARE NON-VISIBLE SHORTER WAVELENGTHS SUCH AS UV LIGHT, OR LONGER WAVELENGTHS SUCH AS INFRA-RED RADIATION.

LIGHT QUALITY

• PLANTS HAVE A GREEN PIGMENT CALLED CHLOROPHYLL WHICH ABSORBS THE LIGHT ENERGY AND THEN TRANSFERS THIS ENERGY TO DRIVE PHOTOSYNTHESIS.

• CHLOROPHYLL MAINLY ABSORBS BLUE AND RED LIGHT.

• THE REASON LEAVES LOOK GREEN IS THAT GREEN LIGHT IS NOT ABSORBED, BUT RATHER REFLECTED BACK OUT. THAT IS WHY YOU SEE LEAVES AS GREEN.

HOW DOES LIGHT WAVELENGTH AFFECT ORCHIDS?

• RED LIGHT INFLUENCES STEM ELONGATION

AND FLOWERING.• BLUE LIGHT INFLUENCES LEAF AND

PSEUDOBULB GROWTH ( MOSTLY EVERYTHING EXCEPT THE FLOWER).

• GREEN, YELLOW, UV, AND INFRA-RED LIGHT DO LITTLE TO INITIATE PHOTOSYNTHESIS.

LIGHT MEASUREMENT TERMINOLOGY

• FOOTCANDLE: MEASURABLE UNIT OF ILLUMINANCE (BRIGHTNESS) EQUAL TO ONE LUMEN PER SQUARE FOOT.

• LUMENS: A QUANTITATIVE MEASURE OF THE HUMAN VISUAL RESPONSE TO OPTICAL POWER.

• IN OTHER WORDS, LUMENS ARE WHAT A LIGHT BULB EMIT. FOOTCANDLES ARE THE MEASUREMENT THAT CAN BE TAKEN WHEN THE “LUMENS” STRIKE A PLANT SURFACE.

• WATTS: A PHYSICAL UNIT OF POWER OR THE FLOW OF ENERGY.• MANY TIMES WHEN YOU BUY A LIGHT BULB, IT WILL BE COMPARED

TO THE STANDARD INCANDESCENT LIGHT BULB. FOR EXAMPLE: A FOUR FOOT FLUORESCENT BULB MIGHT BE DESCRIBED AS EMITTING LIGHT EQUAL TO A 40 WATT INCANDESCENT LIGHT BULB.

DIFFERENT TYPES OF LIGHT BULBS

• INCANDESCENT: A BULB WHICH PRODUCES LIGHT BY THE ELECTRICAL HEATING OF A MATERIAL (INCANDESCENCE). THESE BULBS PRODUCE HEAT AND CONSUME WATTAGE.

• FLUORESCENT: A BULB WHICH PRODUCES LIGHT BY ELECTRICALLY CHARGING GAS-FILLED TUBES. THESE BULBS PRODUCE LITTLE HEAT, NEED LITTLE WATTAGE, BUT EMIT RELATIVELY WEAK LUMENS.

• HID: HIGH INTENSITY DISCHARGE: BULBS INCLUDE MERCURY VAPOR, HIGH PRESSURE SODIUM, AND METAL HALIDE. THESE BULBS ARE LONG LASTING, ENERGY EFFICIENT, PRODUCE A LARGE AMOUNT OF LIGHT, BUT GENERATE A LOT OF HEAT AND WATTAGE.

• LED: LIGHT EMITTING DIODES: THESE BULBS ARE RELATIVELY NEW AND HAVE TREMENDOUS POTENTIAL IN ORCHID GROWING.

A Light Emitting Diode (LED) is conceptually a laminate of special chemistry which emits light in response to passing electrons.

Different chemistry/filters produce different colors.

Today’s LEDs are complex, multilayered micro-structures.

What is an LED?

Light produced can be limited to plant usable spectrums

Low heat (without requiring the usual electrically heated filament to bring the elements to heated incandescence) 4-10 times more usable light per watt

Longer life- 5-11 times longer life(50,000-70,000 hours vs. 5,000 + hours)

Advantages of LEDs

Replace existing supplemental HPS lights in both cool and intermediate sections with 500 watts red and blue LEDs approx (15% of total HPS) watts of used for east facing lean to greenhouse with Odont/Masd growing temperatures and intermediate for Minicats and others.

Run lights 15 hours/day with photo cutoff during bright sun.

Experiment

Experiment

Saved 1000 Kwhrs/month lights and AC cooling for 6 months/year. About half that in the winter.

About a 5 year payout with LEDs as purchased. Today LEDs are more powerful and affordable.

Results(After 20 months/ 15 hours a day)

Most Odonts have multiple leads and about half of those with multiple full size mature spikes in contrast to previous growing producing only single leads and spike.

Oda. Lavender Lace x Aviewood

Results

Increasing percent of plants with super sized pseudobulbs and multiple leads.

Beginning to get good seedling growth when under bench lights are within inches of leaf tips (awkward watering)

Possible unexpected negative or positive- three Odonts out of approx 20 in spike have apical spike from top of pseudobulb in contrast with previous experience of one of about 200 in 30 years.

Results

Intermediate side results are good but not quite so obvious

Results

Pot. Free Spirit ‘Amy’ AM4 leads open 3 more hidden

Blc.Precious StonesMultiple leads 4” pot

Hknsa. Keepsake ‘Denver Gold’ AM

ResultsPlants do take on a different color at night.

1. LEDs can supplement natural lighting at lower cost than other choices and because of lower heat can very advantageous for cool growing.

2. Red and blue LEDs light supplement combination appears to increase new leads and subsequent flowering and pseudo bulb size

3. For basement cool growing and aquarium growing LED lights appear to be the best choice at this time.

4. Recent performance/cost improvements are real over the last two years.

Conclusions and Recommendations: