Greenhouse growing guide
Suggested types:
Starter Fertilization
1. Introduction
1.1 Greenhouse Crops in Soil
Soil greenhouse farming is an intensive production system where plants are grown in a controlled environment that protects them from the outside weather conditions. Unlike hydroponic or aeroponic crops, plants are grown in natural soil, which is improved to meet the nutritional needs of the crops.
Features of conventional greenhouses:
Use of natural soil as a growing medium.
Use of natural soil as a source of nutrients as a substrate.
Flexibility in water and fertilizer management through hydrofertilization.
Protection from adverse weather conditions (frost, hail).
Extended growing season and increased yields.Soil greenhouse crops are an intensive production system where plants are grown in a controlled environment that protects them from external weather conditions. Unlike hydroponic or aeroponic crops, plants are grown in natural soil, which is improved to meet the nutritional needs of the crops.
Characteristics of conventional greenhouses:
Use of natural soil as a growing medium.
Controlled conditions of temperature, humidity and humidity.
1.2 Advantages of Greenhouse Crops
Productivity and Yield
Continuous production year-round, regardless of season
High yields due to controlled growth conditions
Economic Benefits
Extended growing season and the ability to market off-season at premium prices
Improved product quality, enhancing commercial value
Environmental Benefits
Reduced water consumption through targeted irrigation and fertigation
Limited pesticide use via integrated pest management (IPM) systems
Flexibility and Adaptability
Capability to cultivate diverse crops (vegetables, fruits, aromatic plants)
Implementation of modern technologies such as soil sensors and precision systems
2. Crops grown in greenhouses
2.1 Vegetables (Main Crops)
Vegetables account for 70–80% of greenhouse crops due to high demand and the possibility of continuous production.
Tomato (Solanum lycopersicum)
Suitable varieties: High-yield hybrids (e.g., disease-resistant improved varieties).
Nutritional requirements: High in Potassium (K) and Nitrogen (N) for fruit development.
Fertilization: Fertigation with balanced nutrient programs (e.g., N-P-K 10-10-30 + micronutrients).
Cucumber (Cucumis sativus)
Suitable varieties: Parthenocarpic types for greenhouse production.
Nutritional requirements: Potassium (K) for fruit quality and resistance, Calcium (Ca) for crack resistance.
Fertilization: Frequent fertigation applications emphasizing Potassium.
Pepper (Capsicum annuum)
Suitable varieties: Colored and sweet pepper cultivars.
Nutritional requirements: Phosphorus (P) for root development and Potassium (K) for fruit size increase.
Fertilization: Balanced supply of macro- and micronutrients via foliar sprays and fertigation.
Lettuce (Lactuca sativa)
Suitable varieties: Leaf types (Batavia) and Iceberg.
Nutritional requirements: High Nitrogen (N) demand for vegetative growth.
Fertilization: Rapid absorption with foliar feeding to improve growth.
2.2 Aromatic Plants and Herbs
This category is ideal for small-scale cultivation due to the high value and demand for medicinal and aromatic products.
Basil (Ocimum basilicum):
Nutritional requirements: Balanced fertilizers (N-P-K 20-20-20 + micronutrients).
Fertilization: Small, frequent doses for continuous leaf production.
Parsley (Petroselinum crispum):
Nutritional requirements: Nitrogen (N) and Magnesium (Mg) for lush green growth.
Fertilization: Fertigation with nitrate nitrogen and magnesium sulfate.
Rosemary (Rosmarinus officinalis):
Nutritional requirements: Phosphorus (P) for root development.
Fertilization: Foliar application of micronutrients such as iron (Fe).
2.3 Strawberries and High Value Crops
Strawberries are grown in common greenhouses for early production and high market prices.
Nutritional Requirements:
Potassium (K) for fruit development and quality.
Calcium (Ca) for resistance to rot.
Boron (B) for flower development.
Fertilization:
Fertigation with balanced fertilizers (N-P-K 10-10-30 + micronutrients) during fruit set.
Foliar sprays with calcium and magnesium to enhance fruit durability.
2.4 Experimental and New Crops
Blueberries (Vaccinium spp.):
High demand and high yield on acidic soils (pH 4.5–5.5).
Specialized nutrition with potassium sulfate and iron sulfate.
Small-scale Vegetables:
Zucchini, eggplants, and spinach for product variety.
Crop rotation practiced to prevent soil depletion and pathogen buildup.
3. Nutrition and Fertilization in Greenhouses
3.1 Soil Analysis and Nutrient Needs Assessment
Soil analysis is the starting point for proper fertilization management in greenhouses. It provides accurate information about the soil’s chemical composition, nutrient levels, and physical properties, aiding targeted fertilizer application.
3.1.1 Importance of Soil Analysis
Soil analysis determines macronutrients (N, P, K, Mg), micronutrients (Fe, B, Zn, Mn), pH and electrical conductivity (EC), organic matter (OM), and cation exchange capacity (CEC).
Benefits include preventing over-fertilization and toxicity, reducing costs via targeted fertilization, improving crop productivity and quality, and maintaining environmental balance by minimizing nitrate losses.
3.1.2 Sampling and Analysis Methods
Proper soil sampling is essential for accurate results.
Sampling Steps:
Sampling Time:
1–2 months before planting or fertilizer application.
Sampling Point Selection:
Divide the field into homogeneous zones based on use (e.g., different crops or soil conditions).
Collect 10–15 samples from each zone at a depth of 20–30 cm.
Sample Mixing and Processing:
Combine subsamples into a composite sample weighing 1–2 kg.
Laboratory Analysis:
Test for macro- and micronutrients, pH, electrical conductivity (EC), and organic matter.
3.1.3 Interpretation of Soil Analysis Results
Proper interpretation of soil analyses guides fertilization strategies.
Soil pH
Optimal pH: 6.0–6.8 for most vegetables.
Adjustments include adding calcium carbonate (CaCO₃) to raise pH in acidic soils and using ammonium sulfate or iron sulfate to lower pH in alkaline soils.
Electrical Conductivity (EC)
Optimal EC: 1.2–2.5 dS/m.
High EC requires salt leaching via irrigation, while low EC indicates the need for additional fertilization.
Organic Matter (OM)
Ideal content is 2–3% for fertile soil.
This can be improved by adding compost, animal manure, or plant residues.
Macronutrients and Micronutrients
Nitrogen (N): Minimum 20–40 mg/kg for foliage growth.
Phosphorus (P): Ideal 10–30 mg/kg for root development.
Potassium (K): Ideal 150–300 mg/kg for fruit quality.
Calcium (Ca) and Magnesium (Mg): Balanced levels to maintain physiological functions.
3.1.4 Analysis-based lubrication planning
Personalizing fertilization is the next step after analysis.
Program Design:
Production goals and crop needs by growth stage.
Correction of deficiencies with specific fertilizers (e.g., boron, iron).
Fertilizer Calculation:
Nutrient deficiencies identified from analysis.
Determination of net requirement (kg/hectare) for each nutrient.
Application of Fertigation or Topdressing:
Frequent applications of small doses to avoid losses.
Use of fertilizers with inhibitors for uniform supply.
3.2 Macronutrients and trace elements
Plant nutrition in greenhouse cultivation relies on supplying macronutrients and micronutrients essential for growth, fruiting, and overall plant health.
3.2.1 Macronutrients (Macronutrients)
Macronutrients are required in large amounts and form the foundation of plant growth.
1. Nitrogen (N)
Role:
Promotes leaf and shoot growth.
Essential for photosynthesis (chlorophyll synthesis) and protein formation.
Deficiency symptoms:
Yellowing (chlorosis) of older leaves.
Reduced growth and yield.
Sources:
Nitrate nitrogen (NO₃⁻): Fast absorption, suitable for fertigation.
Ammonium nitrogen (NH₄⁺): Slow release, improves root development.
Dose:
15–30 kg/hectare per growing season depending on growth stage.
2. Phosphorus (P)
Role:
Enhances root development and flowering.
Important for energy transfer (ATP).
Deficiency symptoms:
Purple coloration on leaves and shoots.
Reduced root growth.
Sources:
Water-soluble phosphate fertilizers (e.g., MAP – Monoammonium Phosphate).
Dose:
5–10 kg/hectare at planting.
3. Potassium (K)
Role:
Regulates water movement and stress tolerance (drought, frost).
Improves fruit quality (taste, color).
Deficiency symptoms:
Leaf edge burn and chlorosis.
Low resistance to mechanical damage and diseases.
Sources:
Potassium sulfate (K₂SO₄): Low salinity, suitable for sensitive crops.
Potassium nitrate (KNO₃): Combines nitrogen and potassium for rapid absorption.
Dose:
20–40 kg/hectare per growth stage.
4. Calcium (Ca)
Role:
Structural element of cell walls.
Protects against fruit cracking and rot (e.g., tomato blossom end rot).
Deficiency symptoms:
Deformed fruits and signs of rot.
Sources:
Calcium nitrate (Ca(NO₃)₂): Suitable for foliar application.
Dose:
10–15 kg/hectare via fertigation or sprays.
5. Magnesium (Mg)
Role:
Central element in chlorophyll (photosynthesis).
Enzyme activator for energy metabolism.
Deficiency symptoms:
Yellowing between veins on older leaves.
Sources:
Magnesium sulfate (MgSO₄): Water soluble and suitable for foliar applications.
Dose:
3–6 kg/hectare.
6. Sulfur (S)
Role:
Protein and vitamin synthesis.
Enhances disease resistance.
Deficiency symptoms:
Uniform yellowing of young leaves.
Sources:
Ammonium sulfate ((NH₄)₂SO₄) or potassium sulfate (K₂SO₄).
Dose:
5–10 kg/hectare.
3.2.2 Micronutrients
Micronutrients are required in small amounts but are essential for normal plant development.
Iron (Fe):
Chlorophyll synthesis.
Problems in alkaline soils (pH >7.5).
Boron (B):
Flower development and pollination.
Prevents fruit cracking and deformities.
Zinc (Zn):
Hormone and enzyme synthesis.
Shoot development.
Manganese (Mn):
Regulates photosynthesis.
Activates enzymes.
Application:
Foliar sprays with chelated forms (EDDHA, EDTA) for rapid absorption.
Dosages: 0.5–1 kg/hectare per element, depending on soil analysis.
3.3 Fertilisation Programmes by Growth Stage
Fertilization in soil-based greenhouse cultivation must be targeted and tailored to the plants’ needs at each growth stage. Combining base fertilization, fertigation, and foliar applications ensures optimal growth and productivity.
3.3.1 Soil Preparation Stage (Pre-Planting)
Objective:
Improve soil fertility before planting.
Ensure essential nutrients for early growth stages.
Fertilizers and Dosages:
Organic Matter:
Compost or well-rotted manure: 3–4 tons/hectare.
Improves soil structure and water retention capacity.
Phosphorus (P):
10–15 kg/hectare (e.g., Monoammonium Phosphate – MAP).
Promotes root development and young shoot growth.
Potassium (K):
15–20 kg/hectare (e.g., Potassium Sulfate – K₂SO₄).
Ensures stress tolerance and supports fruit quality.
Calcium (Ca):
10–12 kg/hectare (e.g., Calcium Nitrate – Ca(NO₃)₂).
Improves soil structure and reduces acidity (pH).
Preparation Tasks:
Incorporate fertilizers with deep tillage (30–40 cm).
Level the soil for uniform irrigation.
Apply solarization or other techniques to control soil-borne pathogens.
3.3.2 Germination and shoot development stage (0-30 days after planting)
Objective:
Promote vigorous vegetative growth and root system development.
Fertilizers and Dosages:
Nitrogen (N):
10–15 kg/hectare applied as ammonium nitrate or urea.
Fertigation in small, frequent doses for gradual uptake.
Magnesium (Mg):
2–3 kg/hectare (e.g., Magnesium Sulfate – MgSO₄).
Enhances photosynthesis and energy metabolism.
Micronutrients (Fe, Zn, Mn):
Foliar sprays with chelated forms (EDDHA, EDTA).
Dosage: 0.5–1 kg/hectare per element.
Techniques:
Fertigation 1–2 times per week.
Foliar sprays for rapid absorption during critical growth stages.
3.3.3 Flowering and fruiting stage (30-60 days after planting)
Objective:
Enhance flowering, pollination, and fruit set.
Fertilizers and Dosages:
Phosphorus (P):
5–10 kg/hectare (e.g., Monopotassium Phosphate – MKP).
Strengthens roots and plant resilience.
Potassium (K):
15–25 kg/hectare (e.g., Potassium Nitrate – KNO₃).
Improves fruit quality and stress tolerance.
Boron (B):
0.2–0.5 kg/hectare via foliar spray.
Promotes fertilization and fruit set.
Techniques:
Fertigation every 3–4 days with water-soluble fertilizers.
Combined with foliar sprays at critical flowering stages.
3.3.4 Maturing and harvesting stage (60-120 days after planting)
Objective:
Maintain fruit quality and enhance resistance to transport and shelf life.
Fertilizers and Dosages:
Potassium (K):
5–10 kg/hectare (e.g., Potassium Sulfate – K₂SO₄).
Supports sugar accumulation and skin firmness.
Calcium (Ca):
10–12 kg/hectare via calcium nitrate.
Protects against fruit cracking and rot.
Zinc (Zn) and Manganese (Mn):
Foliar sprays at 0.3–0.5% concentration to maintain quality.
3.4 Fertiliser application techniques
Effective fertilization in greenhouse cultivation depends on the correct application method and timing. The main techniques include base fertilization, fertigation, foliar feeding, and the use of fertilizers with urease and nitrification inhibitors.
3.4.1 Basic Soil Preparation Fertilisation
Description:
Applied before planting to improve soil fertility.
The goal is to supply phosphorus (P), potassium (K), and calcium (Ca) for initial plant development.
Application Steps:
Incorporate organic matter by adding compost or manure.
Apply phosphorus and potassium: 10–15 kg P/ha and 15–20 kg K/ha.
Adjust pH using lime (CaCO₃) or ammonium sulfate ((NH₄)₂SO₄).
Deep tillage (30–40 cm) to incorporate fertilizers and enhance nutrient uptake.
Advantages:
Provides long-lasting nutrient availability.
Improves soil structure and moisture retention.
Ideal for plants with demanding root systems.
3.4.2 Fertigation
Description
Combines irrigation with fertilization, enabling uniform nutrient delivery to the roots.
Widely used in greenhouse cultivation due to its precision and flexibility.
Application Steps
Calculate nutrient requirements based on soil analyses and plant growth stage.
Prepare nutrient solution using water-soluble fertilizers such as N-P-K 10-10-30 + micronutrients.
Schedule irrigation with small, frequent applications (e.g., 3–5 times per week).
Monitor electrical conductivity (EC); optimal EC values range from 1.2 to 2.5 dS/m depending on the crop.
Advantages
Uniform fertilizer distribution in the root zone.
Prevents nutrient loss through leaching.
Enables quick correction of deficiencies with immediate absorption.
Ideal for crops with high water and nutrient demands.
3.4.3 Foliar Fertilization (Foliar Fertilization)
Description
Application of nutrients directly to leaves via spraying.
Used for rapid correction of deficiencies or to boost growth during critical stages.
Suitable Nutrients
Micronutrients (Fe, Zn, B): Absorbed quickly through leaves.
Magnesium (Mg): Enhances photosynthesis and energy production.
Calcium (Ca): Prevents diseases like blossom end rot in tomatoes.
Application Steps
Preparation of solution: Use chelated forms (EDDHA, EDTA) for high availability.
Spray timing: Early morning or late afternoon to reduce evaporation.
Solution concentration: Typically 0.1–0.5% (e.g., 100–500 g fertilizer per 100 L water).
Advantages
Immediate nutrient absorption.
Ideal for correcting deficiencies during the growing season.
Used as a supplementary treatment alongside soil fertilization.
4. Irrigation and Water Management
4.1 Irrigation systems in greenhouses
Drip Irrigation
Delivers precise amounts of water directly to the root zone.
Reduces water loss through evaporation.
Allows fertigation (combined fertilization and irrigation).Sprinkler Irrigation
Suitable for crops with high leaf moisture requirements.
Mainly used for leafy vegetables (e.g., lettuce).Substrate Hydroponics
Uses controlled substrates such as perlite or peat, combining water and fertilization.
4.2 Irrigation scheduling
Water Needs Analysis
Calculation based on:
Growth stage.
Climatic conditions.
Soil water retention capacity.
Calculation Methods
Soil moisture sensors: Record real-time moisture levels.
Evapotranspiration (ET) meters: Calculate water loss from plant and soil.
Chlorophyll and NDVI indices: Monitor plant health to detect water deficiencies early.
Irrigation Programs
Vegetative stage: Small, frequent irrigations.
Fruit set stage: Increased water volume to support fruit development.
Ripening stage: Gradual reduction to concentrate sugars and improve fruit quality.
4.4 Relationship between Irrigation and Nutrition (Hydropollution)
Fertigation allows the combined delivery of water and nutrients through irrigation systems.
Advantages of Fertigation:
Targeted nutrient supply directly to the roots.
Reduction of nutrient losses through leaching.
Ability for rapid correction of deficiencies.
5. Plant Protection and Crop Care
5.1 Protection from Diseases and Pests
Soil Pests (Nematodes):
Prevention: Soil disinfection via solarization or steaming.
Control: Biological agents and nematicides.Diseases (Fungi, Bacteria):
Prevention: Good drainage, ventilation, and tool sanitation.
Control: Fungicides and bactericides integrated within an IPM program.Insect Pests (Thrips, Whitefly):
Prevention: Pheromone traps and beneficial insects (e.g., Encarsia formosa).
Control: Biological and chemical insecticides with targeted applications.
5.2 Cultivation Care
Pruning and Trellising:
Enhances ventilation and prevents moisture buildup that favors diseases.Soil Mounding and Cultivation:
Improves root growth and reduces weed pressure.Greenhouse Cleaning:
Removal of plant residues and disinfection to reduce pathogens.Management of New Plantings:
Scheduling planting to minimize infestations from seasonal pests.
