What is Light?What is Light?
-Light is electromagnetic radiation that has a wavelength between 4,000 (violet) to about 7,700 (red) angstroms
-Utilized by plants during photosynthesis
- Measured in Lumens and Foot Candles (for our purposes)
Foot CandleFoot Candle
Basic unit of light intensity
Measured in Square Feet
One lumen per sq.ft. = 1 foot candle (500 lumens per sq.ft. = 500 fc)
How Much Light to ExpectHow Much Light to Expect
Average lit room is about 7 foot candlesAverage lit room is about 7 foot candlesSummer days can be close to 12,000 Summer days can be close to 12,000
Foot CandlesFoot CandlesCloudy days can vary from around Cloudy days can vary from around
1,000 to below 300 Foot Candles1,000 to below 300 Foot CandlesFull Moon Light- .02 Foot CandlesFull Moon Light- .02 Foot CandlesStarlight- .000011Starlight- .000011
Why Light is important?Why Light is important?
When light is absorbed by a plant leaf, it is used as the main energy source to start extremely important processes such as photosynthesis (Light, CO2, and Water)
It also aids in the maintaining of homeostasis.
http://www.bbc.co.uk/gardening/htbg/videos/the_importance_of_light.shtml
200 - 280 nm
UVC ultraviolet range which is extremely harmful to plants because it is highly toxic.
280 - 315 nm
Includes harmful UVB ultraviolet light which causes plants colors to fade.
315 - 380 nm
Range of UVA ultraviolet light which is neither harmful nor beneficial to plant growth.
380 - 400 nm
Start of visible light spectrum. Process of chlorophyll absorption begins.
400 - 520 nm
Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis. (promotes vegetative growth)
520 - 610 nm
green, yellow, and orange bands - less absorption by pigments.
610 - 720 nm
red band. Large absorption by chlorophyll occurs, most significant influence on photosynthesis. (promotes flowering and budding)
720 - 1000 nm
There is little absorption by chlorophyll here. Flowering and germination is influenced.
1000+ nmTotally infrared range. All energy absorbed at this point is converted to heat.
Determine Your Lighting Needs!Determine Your Lighting Needs!
KnowKnow what the requirements are for your crop
KnowKnow the type of weather you haveIf beginning in a new area, looklook at old
weather data to determine the number of cloudy days for years past.
What are the options?What are the options?
Natural… you get it whether you like it or not!
Artificial…like a Loan Shark… you may need one, but its gonna cost you.
Shading… A good dark side???
Natural Lighting Natural Lighting
Cheap source of lighting and is the first choice for most growers
In the South, sunlight is usually not a problem… usually!usually!
Intensity Can Be Controlled (with labor with labor and or investment)and or investment)
Helps warm a greenhouse during winter.It is what most plants are accustomed to.
Negative Aspects of Negative Aspects of Natural LightingNatural Lighting
Uncontrollable- We must accept what nature gives us. (Cloudy, dark)
Not all plants are sun lovers and can tolerate full sun- African Violets (only about 1000 fc)
Artificial LightArtificial LightEnables a grower to extend the
growing dayCan be used for night breaks on
plants(shortens day length)Can be utilized on cloudy days, so
plants can perform betterCan provide red light or blue lightRedRed for flowering/BlueBlue for Vegatative
Not So Good ThingsNot So Good Things About Artificial Light About Artificial Light
Initial Cost is sometimes extreme Your greenhouse may need upgrades (electrical,
support for lights, rearrangement, etc) Use electricity Electricity may not always be available
(Thunderstorms in the South) All add up to $$$$$$$$$$$$$$$$
What are the options?What are the options?
Metal Halide Lighting ComparisonMetal Halide Lighting Comparison
Wattage
Lumens/Watt
Total Lumens
Light Intensity(in foot candles)
175 80 14,000 650
250 82 20,500 950
400 100 40,000 1875
1000 120 120,000 5600
What are the options?What are the options?
Sodium Vapor Lighting ComparisonSodium Vapor Lighting Comparison
Wattage
Lumens/Watt
Total Lumens
Light Intensity(in foot candles)
150 106 16,000 750
250 110 27,500 1718
400 100 50,000 1875
600 150 90,000 4218
1000 140 140,000 8750
COSTCOST
Around $2.65ft² for High Intensity Discharge
(light wattage / 1000) x electricity cost per kilowatt hour = Operating cost per hr
operating cost per hour x hours used per month = Operating cost per month
HID Light Output
Primary Growing
Area
Supplemental Growing
Area
100 watts 2' x 2' 3' x 3'
250 watts 3' x 3' 5' x 5'
400 watts 5' x 5' 8' x 8'
600 watts 6' x 6' 10' x 10'
1000 watts 8' x 8' 12' x 12'
Unifier 400 MH (36,000 lumens)
Price: $215$215
Unifier 1000 MH (110,000 lumens)
Price: $255$255
Unifier 400 HPS (50,000 lumens)
Price: $229$229
Unifier 1000 HPS (140,000 lumens)
Price: $319$319
30x75 GH=2250ft²: 2250/ 144= 15.625 or 1616 1000w HPS lights
16 x $319= $5104$5104/2250= $2.27$2.27 ft² for a good supplemental light system (Initial Cost)
Benefits and DrawbacksBenefits and Drawbacks
Can be used to keep plants from burning up Can be used to lower the temperature of
greenhouse Can grow certain plants outside in a shade house
(Low overhead) Pulling shade can be labor intensive $$$$ Can be automated Sometimes it is unwanted (Too much
Superstructure)
A Few Recommendations By A SupplierA Few Recommendations By A Supplier
-30%30% Chrysanthemums, Asters, Snapdragons, Chrysanthemums, Asters, Snapdragons, GeraniumsGeraniums
--47%47% Various Vegetables & Herbs, Iris, Lilies, Various Vegetables & Herbs, Iris, Lilies, Gloxinias, Misc. Bedding PlantsGloxinias, Misc. Bedding Plants
--55%55% Bromeliads, Ficus, Orchids Bromeliads, Ficus, Orchids--63%63% Orchids Orchids ––73%73% Ferns, Philodendron, Orchids Ferns, Philodendron, Orchids--78%78% Ginseng (Special lath weave fabric for ginseng Ginseng (Special lath weave fabric for ginseng
growers) growers) --80%80% Similar to 73% Similar to 73% --92%92% Aglaonema (Chinese Evergreen) Aglaonema (Chinese Evergreen)
CostCostof of
ShadeShade
30%30% $.13sq/ft $.13sq/ft
40%40% $.15sq/ft $.15sq/ft
50%50% $.16sq/ft $.16sq/ft
60%60% $ .18sq/ft $ .18sq/ft
70%70% $.20sq/ft $.20sq/ft
80%80% $.24sq/ft $.24sq/ft
90% 90% $.25sq/ft $.25sq/ft