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🏠 Types of Greenhouse: Classification by Shape, Material & Temperature

Types of greenhouse based on shape (lean-to, even span, ridge & furrow, quonset, sawtooth, gothic arch), covering material (glass, polyethylene, polycarbonate, FRP), temperature, and ventilation — with comparison tables for exams, NABARD, ICAR, and exams.

What is Protected Cultivation?

Protected cultivation is the technique of growing crops under a controlled or modified environment — shielding plants from adverse climatic conditions and both biotic (pests, diseases) and abiotic (temperature, wind, rain, hail) stresses.

IMPORTANT

Protected cultivation allows year-round production of high-value crops irrespective of season, making it a key topic in IBPS AFO, NABARD Grade A, and FCI exams.

Key Objectives

  • Extend the growing season beyond natural limits
  • Protect crops from extreme weather, pests, and diseases
  • Improve yield quality and quantity
  • Enable off-season production of vegetables, flowers, and fruits
  • Efficient use of water, fertilizers, and land
Comparison of naturally ventilated polyhouse, fan-and-pad greenhouse, shade net house and low tunnel
The main structures differ in ventilation, cooling cost, and crop suitability, so this comparison is worth fixing visually.

Greenhouse / Glasshouse

A greenhouse (also called a glasshouse) is a framed structure covered with transparent or translucent material (glass, plastic, polythene, or fiberglass) in which crops are grown under controlled conditions of temperature, humidity, and light.

How a Greenhouse Works — The Greenhouse Effect

Step Process
1 Short-wave solar radiation passes through the transparent covering
2 Radiation is absorbed by plants, soil, and surfaces inside
3 These surfaces re-radiate energy as long-wave radiation (heat/infrared)
4 Long-wave radiation cannot pass back through glass/plastic — it is trapped inside
5 Temperature inside rises above ambient — the greenhouse effect

TIP

Remember: Short wave enters → converted to long wave (heat) → trapped inside. This is the most frequently asked concept in exams.

Greenhouse effect in protected cultivation showing short-wave light entering a greenhouse and long-wave heat trapped inside
Solar radiation enters as short-wave light, but the re-radiated long-wave heat is retained inside the structure, raising the internal temperature.

Translucent Glass Type

  • Provides uniform diffused light to all plants
  • Preferred for high-value floriculture and vegetable crops

Temperature Management

Season Problem Solution
Winter Heat loss through roof Double layer polythene sheeting over glass roof
Summer Overheating Large evaporative cooling units (fan-and-pad system)
Night Temperature drop Night temperature maintained at 13–15°C

Types of Greenhouse Based on Shape

Greenhouses are classified by four main axes: shape/structure, covering material, temperature regime, and frame material. Shape-based classification is the most tested in exams.

Type Shape Description
Lean-to Right triangle Built against an existing wall/building; one sloping roof side; cheapest; limited to small areas
Even Span Symmetrical gable Both roof slopes equal in length and angle; most common free-standing type
Uneven Span Asymmetric gable Two roof sides of unequal width; used on hillsides to maximize light capture
Ridge and Furrow Joined gable series Multiple even-span units connected at the eave/gutter; saves heating cost; large commercial operations
Quonset (Hoop) Semicircle Half-moon arch; GI pipe frame; low cost; most common polyhouse shape in India
Gothic Arch Pointed arch Stronger than quonset; better rain and snow shedding; improved light at peak
Sawtooth Asymmetric ridges Series of roof ridges each with one near-vertical face; excellent passive ventilation; preferred for hot tropical climates

NOTE

Even span is most common globally. Quonset is most common in India (polyhouse form). Sawtooth is ideal for India's hot plains — the near-vertical face acts as a chimney vent without fans. Ridge and furrow is preferred for large commercial farms as shared walls reduce heating cost.

Shape-based greenhouse comparison showing lean-to, even span, uneven span, ridge and furrow, quonset, gothic arch, and sawtooth structures
Exam questions often test roof geometry, so noticing the silhouette difference between quonset, gothic arch, sawtooth, and gable types helps fast recall.

Shape Comparison — At a Glance

Type Relative Cost Best Climate India Usage
Lean-to Lowest Temperate Small farms, home gardens
Even Span Low–Medium Universal Common free-standing type
Uneven Span Medium Hilly/sloped terrain Hill stations, NE India
Ridge & Furrow High Cool climates Large commercial farms
Quonset Low All (with ventilation) Most common in India
Gothic Arch Low–Medium Heavy rain/snow Hills, flood-prone areas
Sawtooth Medium Hot tropical Recommended for plains India

Types of Greenhouse Based on Covering Material

Material Durability Light Transmission Cost Key Feature
Glass 25+ years ~90% Very high Best clarity; heavy; breakable; traditional
Polycarbonate (twin-wall) 10–15 years 80–85% High Strong; lightweight; excellent insulation
Polyethylene (LDPE/UV film) 2–3 years 85–88% Lowest Cheapest; most widely used in India; UV-stabilized
Fiberglass (FRP) 15–20 years 70–85% Medium Rigid; diffused light; yellows over time
PMMA / Acrylic glass 10+ years ~92% Very high Highest light transmission; costly; specialized use

IMPORTANT

Polyethylene (PE) film — specifically 200-micron UV-stabilized LDPE film — is the most widely used greenhouse covering material in India. It lasts 2–3 years and is replaced periodically. Polycarbonate is used in high-end commercial greenhouses. Glass is reserved for export-quality floriculture and research greenhouses.

Protected cultivation covering materials comparison showing glass, polycarbonate, polyethylene film, fiberglass, and acrylic panels
The key memory hook is that polyethylene film is flexible and low-cost, while glass and polycarbonate suit higher-investment protected structures.

Types of Greenhouse Based on Temperature

Type Minimum Night Temp Crops / Use
Cold / Unheated Just above freezing Frost protection only; hardy plants
Cool greenhouse 4–7°C (or <15°C) Lettuce, spinach, alpine plants, temperate flowers
Warm greenhouse 13–16°C Tomato, capsicum, cucumber, roses, gerbera
Hot / Tropical (Hothouse) 18°C+ Tropical orchids, anthurium, foliage plants

TIP

A "hothouse" implies artificial heating; a "glasshouse" implies glass cladding. These terms are distinct in botany and often tested in exams.

Greenhouse temperature classes showing cold, cool, warm, and hot houses with representative crops
Reading the crop examples with the temperature classes makes it easier to separate frost-protection houses from warm vegetable houses and true tropical hothouses.

Types of Greenhouse Based on Frame Material

Frame Material Durability Cost Notes
Bamboo / Timber ~5 years Very low Low-tech; widely used in tribal/hilly areas; biodegradable
GI (Galvanized Iron) Pipe 15–20 years Medium Most common in Indian polyhouses; rust-resistant
Mild Steel (MS) 20+ years Medium–high Stronger; suited for large structures
Aluminium 25+ years High Corrosion-resistant; used in export-quality greenhouses
PVC Pipe 5–8 years Lowest Ultra-low cost hoop houses; suitable for small farms
Greenhouse frame material comparison showing bamboo or timber, GI pipe, mild steel, aluminium, and PVC pipe structures
Frame questions usually ask you to link cost and durability, and the visual contrast between bamboo poles, GI hoops, and metal trusses helps that stick.

Types of Greenhouse Based on Ventilation

Type Mechanism Cost When to Use
Naturally ventilated Passive — side vents + ridge vents; hot air rises and exits Low Most of India; adequate where summer temp <40°C
Fan-and-pad (Evaporative) Exhaust fans pull air through wet cellulose pads; evaporation cools air Medium–high Arid zones (Rajasthan, Gujarat, Maharashtra plains) where temp regularly exceeds 40°C
Fog/Mist cooling High-pressure nozzles mist water inside; evaporation cools air High High-value crops; tissue culture hardening labs
Sawtooth passive Asymmetric roof creates chimney effect; hot air exits through near-vertical face Medium Hot, humid tropics; preferred over fan-pad for low running cost

IMPORTANT

ICAR/NHB recommendation for India: Naturally ventilated polyhouses are recommended for most parts of India. Fan-and-pad systems are needed only in regions where summer temperatures regularly exceed 40°C.

Protected cultivation ventilation comparison showing naturally ventilated, fan-and-pad, fog or mist cooling, and sawtooth passive systems
Notice how each system removes heat differently: vents rely on buoyancy, fan-pad uses evaporative airflow, mist cools inside the house, and sawtooth roofs vent passively.

Which Type of Greenhouse is Best for India?

India's vast climate diversity means no single type suits all regions:

Region Recommended Type Reason
Plains (UP, Bihar, MP) Naturally ventilated Quonset polyhouse Low cost; adequate passive ventilation
Arid zones (Rajasthan, Gujarat) Fan-and-pad Quonset or Sawtooth Active cooling needed in extreme heat
Hills (Himachal, Uttarakhand, NE) Even span or Uneven span (glass/polycarbonate) Temperature retention in cold winters
Coastal (Kerala, Tamil Nadu) Sawtooth with shade net integration High humidity + heat = max passive ventilation
Commercial floriculture Even span or Gothic arch (polycarbonate) Light uniformity + structural strength

NOTE

The Quonset polyhouse with UV-stabilized PE film and GI pipe frame is India's de facto standard — low cost, NHM subsidy eligible, and suitable for 70% of the country.

India climate-region guide for protected cultivation showing suitable greenhouse types for plains, arid zones, hills, and coastal regions
Regional recommendations become easier when you pair plains with low-cost quonset structures, arid zones with active cooling, hills with temperature-retentive houses, and coasts with sawtooth ventilation.

Polyhouse

A polyhouse is the most common type of protected structure in India. It is a greenhouse covered with UV-stabilized polyethylene film.

Key Specifications

Parameter Detail
Covering material UV-stabilized polyethylene (PE) film
Common thickness 200 micron
Life of PE film 2–3 years
Frame material GI pipes / MS angle / bamboo

Types of Polyhouses

Type Ventilation Cost Area Best For
Naturally ventilated Passive (side & top vents) Low cost < 1000 sq m Tropical & subtropical India
Fan-and-pad Active cooling (exhaust fans + wet cellulose pads) Medium–high Any Arid/hot regions
Fog cooling High-pressure fog nozzles inside High Any High-value crops, tissue culture labs

IMPORTANT

Naturally ventilated polyhouses are recommended for most parts of India by ICAR/NHB due to low cost and suitability to tropical conditions. Fan-and-pad systems are needed only where summer temperatures exceed 40°C regularly.

Indian polyhouse diagram showing UV-stabilized polyethylene film, GI pipe frame, side vents, and naturally ventilated versus fan-and-pad types
The standard Indian polyhouse is easiest to remember as a quonset GI frame covered with UV-stabilized PE film, then modified by either passive or active cooling.

Advantages of Polyhouse Cultivation

  • Year-round production independent of season
  • 5–10 times higher yield compared to open-field cultivation
  • Quality produce — uniform size, color, free from blemishes
  • Water saving of 40–50% through drip irrigation integration
  • Reduced pesticide use — physical barrier against many pests
  • Premium market price for off-season produce
  • Employment generation in rural areas

Shade Net House

A shade net house is a structure covered with knitted nets made of HDPE (High-Density Polyethylene) or polypropylene that filters sunlight to reduce light intensity and temperature.

Shade Net Specifications

Parameter Options
Material HDPE or polypropylene (UV-stabilized, knitted)
Shade intensity available 25%, 35%, 50%, 75%
Most common color Green
Temperature reduction inside 5–8°C below ambient
Other colors available Black, white, red, yellow

Shade Intensity Selection Guide

Shade % Suitable Crops
25% Fruit vegetables (tomato, capsicum) in hot areas
35% Nursery raising, chrysanthemum, gerbera
50% Orchids, ferns, anthurium, leafy vegetables
75% Tissue culture hardening, foliage plants

Uses of Shade Net House

  • Nursery raising — most important commercial use
  • Floriculture crops — gerbera, orchids, anthurium
  • Leafy vegetables — spinach, lettuce, coriander
  • Hardening of tissue-cultured plants
  • Spice crops in tropical areas

TIP

Green shade net is the most commonly used. For exam purposes, remember: shade net reduces temperature by 5–8°C and comes in 25%, 35%, 50%, and 75% shade intensities.

Shade net house for protected cultivation showing nursery use and comparison of 25, 35, 50, and 75 percent shade levels
Different shade percentages are best understood as a practical nursery choice: lighter shade suits vegetables, while heavier shade fits orchids, hardening, and delicate plants.

Mulching

Mulching is the practice of covering the soil surface around plants with organic or inorganic material to conserve moisture, suppress weeds, and regulate soil temperature.

Types of Mulch

A. Organic Mulch

Material Source Key Benefit
Straw/paddy husk Rice harvest residue Excellent moisture retention
Dry leaves Tree leaf fall Adds organic matter on decomposition
Grass clippings Lawn/field trimming Quick decomposition, adds nitrogen
Compost/FYM Decomposed organic matter Improves soil structure & fertility
Sawdust Wood processing Good for acid-loving crops (blueberry)
Coconut coir Coconut husk fiber Long-lasting; good water holding

B. Inorganic/Plastic Mulch

Color Key Function Best Used For
Black Weed suppression (blocks light completely) Most commonly used; all vegetables
Silver/Reflective Insect repellent (reflects light, confuses aphids/whiteflies) Virus-prone crops (tomato, chilli)
Red Reflects far-red light → increases tomato yield Tomato, strawberry
Transparent/Clear Soil solarization (heats soil to kill pathogens/weed seeds) Pre-planting soil treatment
Yellow Attracts & traps insects Integrated pest management
Blue Attracts thrips (used with sticky traps) Floriculture

IMPORTANT

Black plastic mulch is the most commonly used plastic mulch worldwide. It blocks sunlight completely, preventing weed growth. Transparent mulch is used specifically for soil solarization — it heats the soil to 50–60°C to kill pathogens and weed seeds.

Plastic mulch comparison showing black mulch for weed suppression, silver reflective mulch for insect management, red mulch for tomato crops, and transparent mulch for solarization
Mulch colour matters because each film changes the soil and pest environment differently, with black for weeds, silver for reflection, red for crop response, and clear mulch for solarization.

Benefits of Mulching

  • Moisture conservation — reduces evaporation by 25–50%
  • Weed control — suppresses weed germination and growth
  • Soil temperature regulation — keeps soil warm in winter, cool in summer
  • Reduced fruit rot — prevents direct contact of fruit with wet soil
  • Prevents soil erosion and crusting
  • Improves fruit quality (cleaner, less disease)
  • Enhances fertilizer use efficiency

Hydroponics

Hydroponics is the science of growing plants without soil, using a mineral nutrient solution in water.

NOTE

The term "Hydroponics" was coined by W.F. Gericke in 1929 at the University of California. The word comes from Greek: hydro (water) + ponos (labor) = "water working."

Types of Hydroponic Systems

System Mechanism Key Feature
NFT (Nutrient Film Technique) Thin film of nutrient solution flows through shallow channels Most widely used commercial system; continuous flow
DFT (Deep Flow Technique) Plants float on deep pool of nutrient solution Simple; good for leafy greens (lettuce)
Drip / Dutch Bucket Nutrient solution dripped to individual plant containers Best for large fruiting crops (tomato, cucumber)
Aeroponics Roots suspended in air, misted with nutrient solution Most advanced; highest oxygen to roots; fastest growth

TIP

Aeroponics is the most advanced hydroponic technique — roots hang in air and are periodically misted with nutrients. It provides maximum oxygen to roots and is used for high-value crops and seed potato production.

Hydroponic systems comparison showing NFT, DFT, drip bucket, and aeroponics with nutrient solution flow
The fastest way to separate hydroponic systems is to track where the roots sit: thin flowing film, deep solution, individual buckets, or suspended roots in mist.

Advantages of Hydroponics

  • No soil required — can grow on rooftops, deserts, space stations
  • Water saving up to 90% compared to soil cultivation (recirculating systems)
  • No soil-borne diseases or nematode problems
  • Precise control of nutrients — no nutrient wastage
  • Higher plant density → higher yield per unit area
  • Faster growth rate due to optimized nutrition and oxygen

Limitations

  • High initial setup cost
  • Requires technical knowledge and monitoring
  • Power failure can damage crops quickly (pumps stop)
  • Disease spreads rapidly through shared nutrient solution

Other Important Techniques

Protected cultivation management techniques showing fertigation setup, drip irrigation emitters, and tissue culture plantlet hardening
These support techniques work together in practice: fertigation feeds through irrigation, drip targets the root zone, and hardened plantlets are prepared for field survival.

Fertigation

Fertigation is the application of fertilizers through the irrigation system, most commonly through drip irrigation.

Parameter Detail
Definition Fertilizer + Irrigation = Fertigation
Most efficient method Through drip irrigation
Fertilizer saving 25–50% compared to conventional application
Water-soluble fertilizers used MAP, MKP, potassium nitrate, calcium nitrate
Advantage Uniform distribution, precise dosage, labor saving

Drip Irrigation

Drip irrigation (also called trickle irrigation) delivers water directly to the root zone through emitters/drippers at low pressure.

Parameter Detail
Water use efficiency 90–95% (highest among all methods)
Compared to flood irrigation Saves 40–60% water
Compared to sprinkler Saves 20–30% water
Invented by Simcha Blass (Israel, 1960s)
Best suited for Wide-spaced crops, orchards, vegetables

NOTE

Drip irrigation has the highest water use efficiency (90–95%) among all irrigation methods. Sprinkler irrigation efficiency is 70–80%, and flood/surface irrigation is only 30–40%.

Tissue Culture / Micropropagation

Micropropagation is the technique of growing plants from very small plant parts (explants) under aseptic (sterile) conditions on an artificial nutrient medium.

Parameter Detail
Nutrient medium MS Medium (Murashige & Skoog, 1962)
Key components of MS medium Macro & micro nutrients, sucrose, vitamins, agar, growth regulators
Growth regulators used Auxins (root), Cytokinins (shoot)
Important crops Banana, orchids, strawberry, date palm, cardamom
Stages Initiation → Multiplication → Rooting → Hardening

IMPORTANT

MS medium (Murashige and Skoog) is the most widely used culture medium in plant tissue culture. Hardening is the final stage where tissue-cultured plantlets are acclimatized to field conditions — often done in shade net houses (50–75% shade).

Quick Reference

Complete Protected Cultivation Quick Reference Table

Comparison of Protected Structures

Parameter Greenhouse (Glass) Polyhouse (PE film) Shade Net House
Covering Glass UV-stabilized PE film HDPE/PP knitted net
Cost Very high Low to medium Lowest
Durability 25+ years 2–3 years 5–7 years
Light control Excellent Good Moderate (shade only)
Temperature control Excellent (heating + cooling) Good (natural/fan-pad) Limited (5–8°C reduction)
Rain protection Complete Complete Partial
Wind protection Complete Complete Partial
Most used in Europe, USA, Japan India, Southeast Asia India (nurseries)
Ideal crops High-value flowers, vegetables Vegetables, flowers, capsicum Nursery, leafy vegetables, orchids

Key Numbers to Remember

Fact Value
PE film thickness (polyhouse) 200 micron
PE film life 2–3 years
Polyhouse yield increase 5–10x over open field
Water saving (polyhouse) 40–50%
Shade net temperature reduction 5–8°C
Shade net intensities 25%, 35%, 50%, 75%
Drip irrigation efficiency 90–95%
Hydroponics water saving Up to 90%
Mulch evaporation reduction 25–50%
Greenhouse night temperature 13–15°C

Key People & Dates

Person/Term Contribution
W.F. Gericke (1929) Coined the term "Hydroponics"
Simcha Blass (1960s) Invented modern drip irrigation (Israel)
Murashige & Skoog (1962) Developed MS medium for tissue culture

Plastic Mulch Color Functions

Summary Cheat Sheet

Concept / Topic Key Details / Explanation
Protected cultivation concept Protected cultivation means growing crops under a modified environment to avoid biotic and abiotic stress and enable year-round high-value production.
Key objectives The main goals are season extension, stress protection, better quality and yield, off-season production, and efficient use of water, fertilizer, and land.
Greenhouse basics A greenhouse or glasshouse uses transparent or translucent covering so short-wave radiation enters, converts to long-wave heat, and gets trapped inside, producing the greenhouse effect.
Greenhouse classifications Greenhouses are classified by shape, covering material, temperature regime, frame material, and ventilation type.
Shape-based greenhouse types Important shape types are lean-to, even span, uneven span, ridge and furrow, quonset, gothic arch, and sawtooth; quonset is most common in India and sawtooth is preferred for hot tropical plains.
Covering and frame materials Glass, polycarbonate, polyethylene, fiberglass, and acrylic are the main covering materials; 200 micron UV-stabilized polyethylene is most common in India, and GI pipe is the common frame material.
Temperature and ventilation classes Temperature classes include cold, cool, warm, and hot greenhouse; ventilation may be natural, fan-and-pad, fog or mist cooling, or sawtooth passive ventilation, with naturally ventilated polyhouses recommended for most of India.
Best greenhouse choice in India Quonset polyhouse with UV-stabilized PE film and GI pipe is the common Indian standard, while fan-and-pad suits very hot arid regions and sawtooth suits humid tropical climates.

Summary Continued

Concept / Topic Key Details / Explanation
Polyhouse A polyhouse is the most common protected structure in India, usually covered with 200 micron UV-stabilized polyethylene and giving about 5-10x yield increase with 40-50% water saving.
Shade net house Shade net houses use HDPE or polypropylene nets, usually green, with shade levels of 25%, 35%, 50%, and 75%, reducing temperature by about 5-8°C and mainly serving nurseries, floriculture, leafy vegetables, and hardening.
Mulching Mulching may be organic or plastic; black mulch is the most common for weed control, transparent mulch is used for soil solarization, and silver reflective mulch helps insect management.
Hydroponics Hydroponics is soilless cultivation; W.F. Gericke coined the term in 1929; major systems are NFT, DFT, Dutch bucket or drip, and aeroponics, with water saving up to 90%.
Fertigation and drip irrigation Fertigation means fertilizer through irrigation, most efficiently drip; drip irrigation gives about 90-95% water-use efficiency and was developed in modern form by Simcha Blass.
Tissue culture and hardening MS medium by Murashige and Skoog (1962) is the main tissue-culture medium; important crops include banana, orchid, strawberry, date palm, and cardamom; hardening is often done under 50-75% shade net.
Quick memory values Important values from the lesson are greenhouse night temperature 13-15°C, PE film life 2-3 years, shade net temperature reduction 5-8°C, and mulch-driven evaporation reduction 25-50%.

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