Green House LightingGreen House Lighting

Shannon Lawrence

HORT 6050

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)

LumensLumens

It is the basic unit of light

Describes the total amount of light present

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 LightingArtificial Lighting

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?

What are the Options?What are the Options?

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)   

ShadeShade

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

What is right for you?What is right for you?

Evaluate your crop lighting needs

Determine if you are in a low/medium/high light intensity grower

Weigh the costs- can extra expenses be justified?