Hobby GreenhousesHobby Greenhousesand and

Other Growing StructuresOther Growing Structures

Ward Upham

Questions That Must be AnsweredQuestions That Must be Answered

What do you want to accomplish with your What do you want to accomplish with your greenhouse or other structure?greenhouse or other structure? Start plants earlyStart plants early Extend the seasonExtend the season Overwinter plantsOverwinter plants Grow year-roundGrow year-round

What can you afford?What can you afford?

Start Plants EarlyStart Plants Early Light Garden for Germination and early Light Garden for Germination and early

growthgrowth

Light GardenLight Garden May want to use May want to use

bottom heat bottom heat

Light GardenLight Garden Use fluorescents 2 inches above top of Use fluorescents 2 inches above top of

plants (18 hours light, 6 hours darkness) plants (18 hours light, 6 hours darkness)

What if Plants Leggy?What if Plants Leggy?

Increase lightIncrease light Decrease Decrease

temperaturetemperature

Fluorescent LampsFluorescent Lamps T-12 lampT-12 lamp

1500–1700 lumens last 10,000 to 20,000 hours1500–1700 lumens last 10,000 to 20,000 hours Use 40 watts for 48 inch lampUse 40 watts for 48 inch lamp

T-8 lampT-8 lamp 3400 lumens and lasts 40,000 hours3400 lumens and lasts 40,000 hours Use 32 watts for 48 inch lampUse 32 watts for 48 inch lamp

T-5 lampT-5 lamp 5000 lumens and lasts 30,000 hours5000 lumens and lasts 30,000 hours Uses 54 watts for 48 inch lampUses 54 watts for 48 inch lamp

Start Plants EarlyStart Plants Early Light Garden for Germination and early Light Garden for Germination and early

growthgrowth Cold Frame and Hotbed to grow to Cold Frame and Hotbed to grow to

transplant size.transplant size.

Coldframes & HotbedsColdframes & Hotbeds

ColdframesColdframes No supplemental heatNo supplemental heat

HotbedsHotbeds Supplemental heat. Supplemental heat.

Supplemental HeatSupplemental Heat 12 to 18 inches of manure under hotbed 12 to 18 inches of manure under hotbed

with 4 to 6 inches of soil on topwith 4 to 6 inches of soil on top Plant when soil temp drops to 85 degreesPlant when soil temp drops to 85 degrees

Supplemental HeatSupplemental Heat ManureManure Electric cableElectric cable

Coldframe & HotbedColdframe & Hotbed

Conserving EnergyConserving Energy

Conserving EnergyConserving Energy

Extend the Growing SeasonExtend the Growing Season Hoophouses (High Tunnels) are relatively Hoophouses (High Tunnels) are relatively

inexpensive (compared to greenhouses)inexpensive (compared to greenhouses) Greenhouses ($20/sq ft) High Tunnels Greenhouses ($20/sq ft) High Tunnels

($.50/ sq ft)($.50/ sq ft)

High TunnelsHigh Tunnels Single layer of plasticSingle layer of plastic No heat or cooling (other than venting)No heat or cooling (other than venting) Irrigation a mustIrrigation a must

High TunnelsHigh Tunnels Tomatoes ripen 3 to 4 weeks earlier in Tomatoes ripen 3 to 4 weeks earlier in

springspring Tomatoes can be harvested an additional Tomatoes can be harvested an additional

3 weeks in the fall.3 weeks in the fall.

Overwintering PlantsOverwintering Plants

ColdframesColdframes

Overwintering PlantsOverwintering Plants Gus’s GreenhouseGus’s Greenhouse

Gus’s GreenhouseGus’s Greenhouse Wood from discarded cratesWood from discarded crates Did buy plasticDid buy plastic

Overwintering GeraniumsOverwintering Geraniums

HeaterHeater

Growing Year-RoundGrowing Year-Round

ConsiderationsConsiderations Winter growing difficult due to limited quantity Winter growing difficult due to limited quantity

and intensity of lightand intensity of light Winter growing expensive due to fuel costsWinter growing expensive due to fuel costs Summer growing difficult due to temperature Summer growing difficult due to temperature

control and watering demands. Need to have control and watering demands. Need to have some type of shading.some type of shading.

Hobby greenhouses often lack adequate Hobby greenhouses often lack adequate heating and cooling to grow plants year-roundheating and cooling to grow plants year-round

Locating a GreenhouseLocating a Greenhouse

Sun all day (or most of the day) is best for Sun all day (or most of the day) is best for most (not all) plantsmost (not all) plants

Locating a GreenhouseLocating a Greenhouse

Sun all day (or most of the day) is best for Sun all day (or most of the day) is best for most (not all) plantsmost (not all) plants

If must choose between morning sun and If must choose between morning sun and afternoon sun, choose morning sunafternoon sun, choose morning sun

Normally want full sun but may help to Normally want full sun but may help to shade late afternoon sun during the shade late afternoon sun during the summersummer

Types of Greenhouses: Lean-toTypes of Greenhouses: Lean-to

Line Drawing Courtesy of West Virginia University

Lean-To GreenhouseLean-To Greenhouse

AdvantagesAdvantages Least expensiveLeast expensive Easy accessEasy access Insulation for and from adjoining structureInsulation for and from adjoining structure

DisadvantagesDisadvantages Size limited by structureSize limited by structure Dirt and insects tracked into adjoining structureDirt and insects tracked into adjoining structure MoistureMoisture

Types of Greenhouses: Types of Greenhouses: Free-StandingFree-Standing

Line Drawing Courtesy of West Virginia University

Free-Standing GreenhouseFree-Standing Greenhouse

AdvantagesAdvantages More flexibility in location and useMore flexibility in location and use Easy expansionEasy expansion Private Get-awayPrivate Get-away

DisadvantagesDisadvantages More difficult accessMore difficult access Separate utilities must be runSeparate utilities must be run Higher energy costsHigher energy costs

Types of Greenhouses: PitTypes of Greenhouses: Pit

Pit GreenhousePit Greenhouse

AdvantagesAdvantages Less energy required to heat and coolLess energy required to heat and cool Temperature more constantTemperature more constant

DisadvantagesDisadvantages Access more difficultAccess more difficult Need sump pump to get rid of excess waterNeed sump pump to get rid of excess water More expensive to buildMore expensive to build

GlazingsGlazings

The more light transmitted, the betterThe more light transmitted, the better For every 1% reduction in light received, For every 1% reduction in light received,

there is a 1% reduction in plant growth there is a 1% reduction in plant growth (unless you are over 3500 foot candles of (unless you are over 3500 foot candles of light)light)

Types of Greenhouse CoveringsTypes of Greenhouse Coverings

GlazingGlazing $/Sq Ft$/Sq Ft LifeLife Light TransLight Trans

GlassGlass $2 - $7$2 - $7 > 25 yrs> 25 yrs 77% double77% double

Sheet PolySheet Poly $.18 - $.20$.18 - $.20 3 – 4 yrs3 – 4 yrs 76% double76% double

PolycarbonatePolycarbonate $1.75 – 2.50$1.75 – 2.50 20-25 yrs20-25 yrs 83% double83% double

AcrylicAcrylic $1.50 – 3.50$1.50 – 3.50 20-25 yrs20-25 yrs 90% double90% double

Above info from University of Arkansas

Other CommentsOther Comments

Glass:Glass: Heavy and subject to breakage Heavy and subject to breakage Poly film:Poly film: Cheap but short-lived. Must be Cheap but short-lived. Must be

UV treated. Best if inner layer is IR film that UV treated. Best if inner layer is IR film that is anti-condensate.is anti-condensate.

Polycarbonate:Polycarbonate: Can be scratched but more Can be scratched but more resistant than acrylic. Also, less flammable resistant than acrylic. Also, less flammable than acrylic. High expansion and contractionthan acrylic. High expansion and contraction

Acrylic:Acrylic: Easily scratched, flammable, lower Easily scratched, flammable, lower impact resistance than polycarbonate. Also, impact resistance than polycarbonate. Also, high expansion & contractionhigh expansion & contraction

Greenhouse EnvironmentGreenhouse Environment

HeatingHeating CoolingCooling Air circulationAir circulation VentilationVentilation

VentilationVentilation

Roof vents can be operated by solar Roof vents can be operated by solar powered powered

Need vent for cool air (doors or dedicated Need vent for cool air (doors or dedicated vents.vents.

Air CirculationAir Circulation

FansFans

Helps cut down on Helps cut down on diseasedisease

HeatingHeating

Gas (7,000 BTU @ $649)Gas (7,000 BTU @ $649) Electric (7,600 BTU @ $324) 240 voltElectric (7,600 BTU @ $324) 240 volt WoodWood

Heater BTU Rating Heater BTU Rating Needed Varies WithNeeded Varies With

Size of greenhouse (Sq ft and height)Size of greenhouse (Sq ft and height) ExposureExposure Coldest temperature expectedColdest temperature expected Free-standing or lean-toFree-standing or lean-to

CoolingCooling Shade clothShade cloth Often reduces sunlight by about 50%.Often reduces sunlight by about 50%.

CoolingCooling Evaporative (Swamp) Cooler for Evaporative (Swamp) Cooler for

greenhouses 200 sq ft or smaller.greenhouses 200 sq ft or smaller. How well works depends on relative humidityHow well works depends on relative humidity Cost $550 to $1500 for “box” models.Cost $550 to $1500 for “box” models.

CoolingCooling

Can also place evaporative pads along one side Can also place evaporative pads along one side of greenhouse for greenhouses over 200 square of greenhouse for greenhouses over 200 square feet.feet.

BenchesBenches

How to Water ProperlyHow to Water Properly

Allow enough time between watering to allow most of the water to be used. Roots must have oxygen.

Apply 10-15% more water than container will hold to leach salts. All fertilizers are salts.

The EndThe End