Modern greenhouse production has evolved to include various methods of providing essential nutrients to crops. Two predominant approaches have emerged as frontrunners: hydroponic systems, which deliver nutrients directly through water solutions, and traditional soil-based systems that leverage the natural nutrient cycling processes of soil.
With increasing demands for food production and the challenges posed by climate change and land scarcity, optimizing greenhouse crop nutrition has never been more important. This blog post explores the fundamental aspects of both hydroponic and soil-based nutrition systems, helping growers make informed decisions for their specific needs and conditions.
"The art of greenhouse nutrition is finding the perfect balance between what plants need and what they can effectively utilize in their specific growing environment."
Before diving into specific growing systems, it's crucial to understand the fundamental nutrients that all plants require for healthy growth. Plants need 17 essential elements to properly function, with each playing specific roles in plant metabolism and growth processes.
Needed in larger quantities, macronutrients form the foundation of plant nutrition:
| Nutrient | Symbol | Primary Functions | Deficiency Symptoms |
|---|---|---|---|
| Nitrogen | N | Chlorophyll production, protein synthesis, vegetative growth | Light green foliage, stunted growth, yellowing of older leaves |
| Phosphorus | P | Energy transfer, root development, flowering, fruiting | Purple or reddish coloration in leaves, stunted growth |
| Potassium | K | Enzyme activation, water regulation, disease resistance | Marginal leaf scorch, weak stems, poor fruit development |
| Calcium | Ca | Cell wall formation, cell division, enzyme activity | Tipburn in lettuce, blossom end rot in tomatoes, stunted root growth |
| Magnesium | Mg | Chlorophyll molecule component, enzyme activator | Interveinal chlorosis in older leaves |
| Sulfur | S | Protein synthesis, enzyme production | General yellowing of plant, similar to nitrogen deficiency |
Required in smaller amounts but equally essential for plant health:
| Nutrient | Symbol | Primary Functions | Deficiency Symptoms |
|---|---|---|---|
| Iron | Fe | Chlorophyll synthesis, electron transport | Interveinal chlorosis in young leaves |
| Manganese | Mn | Photosynthesis, nitrogen metabolism | Interveinal chlorosis with small green veins |
| Zinc | Zn | Hormone production, protein synthesis | Shortened internodes, small leaf size |
| Boron | B | Cell wall formation, reproductive growth | Death of growing points, brittle tissue |
| Copper | Cu | Component of enzymes, lignin formation | Twisted new leaves, wilting |
| Molybdenum | Mo | Nitrogen metabolism, enzyme function | Interveinal mottling, leaf margin necrosis |
| Chlorine | Cl | Photosynthesis, osmotic regulation | Wilting, chlorosis, reduced leaf size |
Plants obtain carbon (C), hydrogen (H), and oxygen (O) from air and water. The remaining essential nutrients must be provided through the growing medium or nutrient solution.
pH Influence on Nutrient Availability: The pH level significantly affects nutrient availability. In hydroponic systems, maintaining pH between 5.5 and 6.5 is generally optimal for most crops, as this range maximizes the availability of most essential nutrients. Outside this range, certain nutrients become less available to plants despite being present in the solution.
Hydroponic systems grow plants without soil, with nutrients delivered directly to the roots through a water solution. This approach offers precise control over plant nutrition but requires careful management.
Plants grow with their roots in a shallow stream of continuously flowing nutrient solution. This thin film provides oxygen, water, and nutrients to the root system.
Best for: Leafy greens, herbs, strawberries
Plant roots are suspended in an aerated nutrient solution. Air pumps provide oxygen to the roots, preventing them from drowning.
Best for: Leafy greens, herbs, fast-growing plants
Nutrient solution is pumped through drip emitters to each plant's base, gradually feeding the growing medium and roots.
Best for: Various crops, especially fruiting crops like tomatoes and peppers
Periodically floods growing trays with nutrient solution, then drains back to the reservoir, providing cycles of nutrient delivery and aeration.
Best for: Versatile system suitable for most crops
Creating the right nutrient solution is critical for successful hydroponic growing. Below are some proven recipes for different crop types:
This modified Sonneveld's solution is suitable for most leafy greens:
Tank A (per 100 gallons)
Tank B (per 100 gallons)
This recipe provides approximately: 150 ppm N, 31 ppm P, 210 ppm K, 90 ppm Ca, 24 ppm Mg, plus essential micronutrients.
UA CEAC Recipe for fruiting vegetables:
Tank A (per 100 gallons)
Tank B (per 100 gallons)
This recipe provides approximately: 189 ppm N, 39 ppm P, 341 ppm K, 170 ppm Ca, 48 ppm Mg, plus essential micronutrients.
For those who prefer a simpler approach, commercial formulations like Jack's Hydro-FeED (16-4-17) offer a complete one-bag solution:
Successful hydroponic nutrition management requires careful monitoring of several parameters:
The pH level significantly impacts nutrient availability. For most hydroponic crops, maintaining a pH between 5.5-6.5 provides optimal nutrient availability. Outside this range, certain nutrients become less available despite being present in the solution.
For managing pH:
EC measures the total dissolved salts in the nutrient solution and serves as an indicator of nutrient concentration. Target EC values vary by crop:
Soil-based greenhouse systems utilize traditional growing media enhanced with various amendments to provide optimal nutrition for crops. These systems rely on the complex biological, chemical, and physical properties of soil to deliver nutrients to plants.
In greenhouse production, "soil-based" typically refers to various growing media rather than field soil. Common components include:
| Component | Properties | Nutritional Contribution |
|---|---|---|
| Peat Moss | Excellent water retention, lightweight, acidic pH | Minimal nutrients but excellent CEC (cation exchange capacity) |
| Coconut Coir | Good water retention, neutral pH, sustainable alternative to peat | Low in nutrients, but contains some potassium |
| Compost | Improves soil structure, adds organic matter | Rich source of macro and micronutrients, beneficial microorganisms |
| Vermiculite | Excellent water retention, moderate CEC | Contains some magnesium, potassium, calcium |
| Perlite | Excellent drainage, aeration | Inert, provides no nutrients |
Organic amendments provide nutrients through natural decomposition processes:
Nutrient Content: Varies widely based on source materials but typically provides balanced nutrition including N, P, K, and micronutrients.
Application Rate: 5-20% by volume mixed into growing media or 1-2 inch layer as top dressing.
Nutrient Content: Rich in nitrogen; content varies by animal source (chicken manure is higher in N than cow manure).
Application Rate: 5-10% by volume in potting mixes. Must be well-composted to prevent pathogen issues.
Nutrient Content: 3-15% phosphorus, 15-25% calcium.
Application Rate: 2-3 lbs per 100 square feet or 1 tablespoon per gallon of potting mix.
Nutrient Content: Low but balanced NPK (typically around 1-0-0), rich in beneficial microorganisms.
Application Rate: 5-20% by volume in potting mixes or as top dressing.
Nutrient Content: Rich in micronutrients, plant hormones, and growth stimulants.
Application Rate: 1-2 lbs per 100 square feet or 1 tablespoon per gallon of potting mix.
Nutrient Content: 20-30% phosphorus (slow-release), calcium.
Application Rate: 5-10 lbs per 100 square feet or 2-4 tablespoons per gallon of potting mix.
Before planting, incorporate base fertilizers and amendments into the growing medium:
For ongoing nutrition in soil-based greenhouse systems, fertigation provides regular nutrient delivery:
These provide extended nutrient availability with fewer applications:
Selecting the right nutrition system depends on various factors including crop type, available resources, scale of production, and grower expertise.
Many successful greenhouse operations implement hybrid approaches that combine elements of both systems:
Regardless of which system you choose, monitoring plant nutrition is critical for successful greenhouse production.
Measures acidity/alkalinity of nutrient solution or soil
Testing Frequency: Daily for hydroponics, weekly for soil
Measures total dissolved solids or electrical conductivity
Testing Frequency: Daily for hydroponics, bi-weekly for soil
Laboratory analysis of plant tissue to determine nutrient levels
Testing Frequency: Monthly or when symptoms appear
Symptoms: Light green to yellow older leaves, stunted growth
Hydroponic Solution: Increase nitrogen in nutrient solution by 20-30%
Soil Solution: Apply blood meal, fish emulsion, or balanced fertilizer
Symptoms: Dark green leaves with purple/red tints, stunted roots
Hydroponic Solution: Check pH (should be 5.5-6.5), increase phosphorus
Soil Solution: Apply bone meal or rock phosphate
Symptoms: Blossom end rot, tipburn in lettuce, stunted growth points
Hydroponic Solution: Add calcium nitrate, check pH, improve air circulation
Soil Solution: Apply gypsum or lime (depending on pH needs)
Symptoms: Yellowing between veins in young leaves
Hydroponic Solution: Add chelated iron (Fe-DTPA or Fe-EDDHA)
Soil Solution: Lower pH if high, apply iron chelates
Symptoms: Interveinal chlorosis in older leaves
Hydroponic Solution: Add magnesium sulfate (Epsom salts)
Soil Solution: Apply dolomitic lime or Epsom salts
Excess of one nutrient can inhibit the uptake of others. Common antagonistic relationships include:
When diagnosing nutrient problems, consider both deficiencies and excesses, as symptoms may be caused by antagonistic relationships rather than absolute deficiencies.
Nutrient requirements change with environmental conditions and should be adjusted seasonally:
Whether you choose hydroponic or soil-based nutrition systems for your greenhouse, success depends on understanding plant needs, regular monitoring, and timely adjustments. Each system offers distinct advantages and challenges, and the best choice often depends on your specific goals, resources, and experience level.
Many successful growers begin with soil-based systems to develop their understanding of plant nutrition before transitioning to hydroponics for certain crops. Others maintain both systems simultaneously, leveraging the strengths of each approach for different crops.
Regardless of your approach, investing time in understanding the fundamental principles of plant nutrition and developing a consistent monitoring routine will pay dividends in crop quality and yield. Remember that plants don't care how they get their nutrients—they just need the right elements in the right proportions at the right time.
"The art of greenhouse nutrition is not about providing the most nutrients, but about providing the right nutrients at the right time in the right balance."