Hobby Greenhouses and Other Growing Structures Ward Upham

Questions That Must be Answered What do you want to accomplish with your greenhouse or other structure? What do you want to accomplish with your greenhouse or other structure? Start plants early Start plants early Extend the season Extend the season Overwinter plants Overwinter plants Grow year-round Grow year-round What can you afford? What can you afford?

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

Light Garden May want to use bottom heat May want to use bottom heat

Light Garden Use fluorescents 2 inches above top of plants (18 hours light, 6 hours darkness) Use fluorescents 2 inches above top of plants (18 hours light, 6 hours darkness)

What if Plants Leggy? Increase light Increase light Decrease temperature Decrease temperature

Fluorescent Lamps T-12 lamp T-12 lamp 1500–1700 lumens last 10,000 to 20,000 hours 1500–1700 lumens last 10,000 to 20,000 hours Use 40 watts for 48 inch lamp Use 40 watts for 48 inch lamp T-8 lamp T-8 lamp 3400 lumens and lasts 40,000 hours 3400 lumens and lasts 40,000 hours Use 32 watts for 48 inch lamp Use 32 watts for 48 inch lamp T-5 lamp T-5 lamp 5000 lumens and lasts 30,000 hours 5000 lumens and lasts 30,000 hours Uses 54 watts for 48 inch lamp Uses 54 watts for 48 inch lamp

Start Plants Early Light Garden for Germination and early growth Light Garden for Germination and early growth Cold Frame and Hotbed to grow to transplant size. Cold Frame and Hotbed to grow to transplant size.

Coldframes & Hotbeds Coldframes Coldframes No supplemental heat No supplemental heat Hotbeds Hotbeds Supplemental heat. Supplemental heat.

Supplemental Heat 12 to 18 inches of manure under hotbed with 4 to 6 inches of soil on top 12 to 18 inches of manure under hotbed with 4 to 6 inches of soil on top Plant when soil temp drops to 85 degrees Plant when soil temp drops to 85 degrees

Supplemental Heat Manure Manure Electric cable Electric cable

Coldframe & Hotbed

Conserving Energy

Extend the Growing Season Hoophouses (High Tunnels) are relatively inexpensive (compared to greenhouses) Hoophouses (High Tunnels) are relatively inexpensive (compared to greenhouses) Greenhouses ($20/sq ft) High Tunnels ($.50/ sq ft) Greenhouses ($20/sq ft) High Tunnels ($.50/ sq ft)

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

High Tunnels Tomatoes ripen 3 to 4 weeks earlier in spring Tomatoes ripen 3 to 4 weeks earlier in spring Tomatoes can be harvested an additional 3 weeks in the fall. Tomatoes can be harvested an additional 3 weeks in the fall.

Overwintering Plants Coldframes Coldframes

Overwintering Plants Guss Greenhouse Guss Greenhouse

Guss Greenhouse Wood from discarded crates Wood from discarded crates Did buy plastic Did buy plastic

Overwintering Geraniums

Heater

Growing Year-Round Considerations Considerations Winter growing difficult due to limited quantity and intensity of light Winter growing difficult due to limited quantity and intensity of light Winter growing expensive due to fuel costs Winter growing expensive due to fuel costs Summer growing difficult due to temperature control and watering demands. Need to have some type of shading. Summer growing difficult due to temperature control and watering demands. Need to have some type of shading. Hobby greenhouses often lack adequate heating and cooling to grow plants year-round Hobby greenhouses often lack adequate heating and cooling to grow plants year-round

Locating a Greenhouse Sun all day (or most of the day) is best for most (not all) plants Sun all day (or most of the day) is best for most (not all) plants

Locating a Greenhouse Sun all day (or most of the day) is best for most (not all) plants Sun all day (or most of the day) is best for most (not all) plants If must choose between morning sun and afternoon sun, choose morning sun If must choose between morning sun and afternoon sun, choose morning sun Normally want full sun but may help to shade late afternoon sun during the summer Normally want full sun but may help to shade late afternoon sun during the summer

Types of Greenhouses: Lean-to Line Drawing Courtesy of West Virginia University

Lean-To Greenhouse Advantages Advantages Least expensive Least expensive Easy access Easy access Insulation for and from adjoining structure Insulation for and from adjoining structure Disadvantages Disadvantages Size limited by structure Size limited by structure Dirt and insects tracked into adjoining structure Dirt and insects tracked into adjoining structure Moisture Moisture

Types of Greenhouses: Free-Standing Line Drawing Courtesy of West Virginia University

Free-Standing Greenhouse Advantages Advantages More flexibility in location and use More flexibility in location and use Easy expansion Easy expansion Private Get-away Private Get-away Disadvantages Disadvantages More difficult access More difficult access Separate utilities must be run Separate utilities must be run Higher energy costs Higher energy costs

Types of Greenhouses: Pit

Pit Greenhouse Advantages Advantages Less energy required to heat and cool Less energy required to heat and cool Temperature more constant Temperature more constant Disadvantages Disadvantages Access more difficult Access more difficult Need sump pump to get rid of excess water Need sump pump to get rid of excess water More expensive to build More expensive to build

Glazings The more light transmitted, the better The more light transmitted, the better For every 1% reduction in light received, there is a 1% reduction in plant growth (unless you are over 3500 foot candles of light) For every 1% reduction in light received, there is a 1% reduction in plant growth (unless you are over 3500 foot candles of light)

Types of Greenhouse Coverings Glazing $/Sq Ft Life Light Trans Glass $2 - $7 > 25 yrs 77% double Sheet Poly $.18 - $.20 3 – 4 yrs 76% double Polycarbonate $1.75 – yrs 83% double Acrylic $1.50 – yrs 90% double Above info from University of Arkansas

Other Comments Glass: Heavy and subject to breakage Glass: Heavy and subject to breakage Poly film: Cheap but short-lived. Must be UV treated. Best if inner layer is IR film that is anti-condensate. Poly film: Cheap but short-lived. Must be UV treated. Best if inner layer is IR film that is anti-condensate. Polycarbonate: Can be scratched but more resistant than acrylic. Also, less flammable than acrylic. High expansion and contraction Polycarbonate: Can be scratched but more resistant than acrylic. Also, less flammable than acrylic. High expansion and contraction Acrylic: Easily scratched, flammable, lower impact resistance than polycarbonate. Also, high expansion & contraction Acrylic: Easily scratched, flammable, lower impact resistance than polycarbonate. Also, high expansion & contraction

Greenhouse Environment Heating Heating Cooling Cooling Air circulation Air circulation Ventilation Ventilation

Ventilation Roof vents can be operated by solar powered Roof vents can be operated by solar powered Need vent for cool air (doors or dedicated vents. Need vent for cool air (doors or dedicated vents.

Air Circulation Fans Fans Helps cut down on disease Helps cut down on disease

Heating Gas (7,000 $649) Gas (7,000 $649) Electric (7,600 $324) 240 volt Electric (7,600 $324) 240 volt Wood Wood

Heater BTU Rating Needed Varies With Size of greenhouse (Sq ft and height) Size of greenhouse (Sq ft and height) Exposure Exposure Coldest temperature expected Coldest temperature expected Free-standing or lean-to Free-standing or lean-to

Cooling Shade cloth Shade cloth Often reduces sunlight by about 50%. Often reduces sunlight by about 50%.

Cooling Evaporative (Swamp) Cooler for greenhouses 200 sq ft or smaller. Evaporative (Swamp) Cooler for greenhouses 200 sq ft or smaller. How well works depends on relative humidity How well works depends on relative humidity Cost $550 to $1500 for box models. Cost $550 to $1500 for box models.

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

Benches

How 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.

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