1
Q
Why use protected environments?
A
Within a protected environment a gardener has some level of control to enable photosynthesis to occur at a favourable rate, therefore growth rate of plants is improved.
2
Q
Protected environment creates a microclimate distinct from outdoors in which ways?
A
- Light intensity can be reduced with shading
- Temperature is higher
- Air turbulence is reduced - shelter from winds reduces transpiration stress on plants
- Relative humidity is difference
- Rainfall is absent so need irrigation
3
Q
Benefits of environmental control
A
- Potentially higher crop yields
- improved quality of product
- Able to grow greater variety of cultivars
- Can extend the growing season
4
Q
Describe a greenhouse
A
- Wooden or galvanised steel framework with aluminium or wooden glazing bars to retain the sheet horticultural glass. Permanent structure with reasonable headroom and growing space. May have enclosed base (reduces heat loss in winter)
- Give gardener most control over growing environment
- Smaller the greenhouse volume, the more difficult it is to control the environment within a tight range
- A heated greenhouse provides an environment enabling growers to propagate and grow plants throughout the year, and to over-winter frost-tender species e.g. sowing seeds.
- Can be used for growing tomatoes, cucumbers, Poinsettias, cyclamen.
- Crops can be grown on benches or on the ground
- Cold greenhouses also extend the season and range of plants that can be grown.
5
Q
Greenhouse protection provides:
A
- Control over temperature range, and other environmental factors; wind and rain
- Light; quality and density
- Water; humidity and soil water
- Pests and Diseases
- Air; movement of air, oxygen and carbon dioxide levels
6
Q
Single span green house
A
- A-shaped roof with vertical sides and vents
- Good all purpose greenhouse
- Permanent structure with reasonable headroom and growing space
- May have enclosed base (reduces heat loss in winter)
- Best use of space for least cost
- Best suited for raising seedlings in spring, growing plants with additional care during summer e.g. tomatoes
7
Q
Describe a Dutch light greenhouse
A
- Large glass panes and sloping sides for maximum light transmission
- Excellent for growing border crops e.g. tomatoes
8
Q
Describe a lean to greenhouse
A
- Has one side against wall - saves heat as wall absorbs heat during day and releases it at night
- Light transmission restricted (as non from side of wall)
9
Q
Describe a Mansard / curvilinear greenhouse
A
- Curved roof shape and high eaves maximise light transmission during winter months - whatever time of year some part of glass is at 90 degrees to sunlight
- Expensive to build
- Curved sides not optimal for vertical growth
10
Q
Describe a cold frame
A
- Box-like structure with solid walls made of wood, metal or brick
- Glass or plastic ‘lights’ which are angled to maximise light transmission
- ‘Lights’ must be moveable for ventilation and temperature regulation
- Unheated
- Based direct on the soil, or shingle bed
- Used to harden off plants, overwinter tender plants
- Ideally orientated east to west with lights sloping to south.
11
Q
Describe a polythene tunnel (walk-in polytunnel)
A
- Steel hoops clad in polythene
- Economic alternative to greenhouse
- Normally non-heated but can be heated if required.
- Less flexible structure compared to glasshouse.
- Limited lifespan
- Retains a high level of humidity; condensation may be a problem without adequate ventilation
- Main use; crops at ground level in the soil or grow bags, pots on ground e.g. celery, strawberries, raspberries, peppers, lettuce
12
Q
Describe a cloches
A
- Low, portable structures of glass or plastic, act like mini greenhouses
- Provide sheltered environment for plants; can extend growing season pre-warming soil in spring and protect plants from early frosts in autumn
- Inexpensive and durable
- Easily installed and removed
- Temperature control limited, cloche either on or off, no half-way
- Also protect plants from drying effect of wind
- Tent cloche: e.g. two pieces of glass placed to form a a tent shape
- Barn cloche: have nearly vertical sides topped with tent-shaped cap. Capable of protecting larger plants but more expensive than tent cloches
- Low tunnel cloches: made from polythene, fleece, mesh or bendable plastic panels with metal hoop support to make continious tunnel
- Floating cloches: sheet of horticultural fleece or perforated polythene placed directly over ground where crops have been sown or planted. Permeable materials e.g. horticultural fleece and perforated polythene allow water to penetrate to the soil
13
Q
Uses of cloches
A
- Protection of newly sown crops in spring and end of season
- Hardening off
- Protection from weather, pests and diseases
- Protecting tender plants
*
14
Q
Describe conservatories
A
- Usually attached to the house
- Higher light levels than other indoor spaces
- Provide moderate climate
- Plants can be exhibited on permanent staging
- May be expensive to heat during winter
- may require shading in summer months to prevent temperatures getting too hot.
- Uses: displaying tender perennials and houseplants
15
Q
Describe horticultural uses for protected environment structures
A
16
Q
Describe how to maximise light transmission in a protected structure
A
- Site selection:
- Site not shaded by trees or existing buildings
- Structure oriented east to west to maximise surface of structure facing south
- Selection of structure:
- Curvilinear or mansard shape with high eaves to optimise angle of incidence for maximum light transmission
- A structure with stronger construction materials e.g. steel and aluminium requires less material which would block out light
- Horticultural glass has greater light transmission than polythene film.
- Growing within structure:
- Use of staged benching will enable several tiers of plants to be accommodated and avoid shading of some plants
- Use of training and support systems to ensure maximum light reaches crop.
17
Q
Name and describe main structural features of these structures
A
Protected environments
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