Building Microgreen Growing Systems: A Global Guide

Microgreens, those tiny edible seedlings, are packed with nutrients and flavor, making them a popular addition to salads, sandwiches, and smoothies worldwide. Growing your own microgreens is surprisingly easy and can be done in various settings, from small apartments to large-scale commercial operations. This comprehensive guide will walk you through the steps of building your own microgreen growing systems, catering to different needs and budgets.

Why Grow Microgreens?

Before diving into the specifics, let's explore why you might want to grow microgreens:

• Nutritional Powerhouse: Microgreens are often more nutrient-dense than their mature counterparts. Studies have shown that they can contain significantly higher levels of vitamins, minerals, and antioxidants.
• Fast Growth: Unlike traditional vegetables, microgreens are ready to harvest in just 7-21 days.
• Space-Saving: Microgreens require minimal space, making them ideal for urban dwellers and those with limited garden space.
• Year-Round Availability: Indoor growing allows you to produce fresh microgreens regardless of the season.
• Sustainability: Growing your own food reduces your carbon footprint and promotes sustainable living.
• Cost-Effective: While there's an initial investment in equipment, growing your own microgreens can save you money compared to buying them from the store.
• Flavor Variety: A wide range of microgreen varieties offers diverse flavors, from spicy radish to sweet sunflower.

Types of Microgreen Growing Systems

Several types of microgreen growing systems can be used, each with its own advantages and disadvantages. Choosing the right system depends on your budget, space, and desired production scale.

1. Basic Tray System

The simplest and most affordable option, a basic tray system consists of a growing tray, a drainage tray, and a suitable growing medium. This system is ideal for beginners and small-scale home growers.

Materials:

• Growing tray (with drainage holes)
• Drainage tray (without drainage holes)
• Growing medium (e.g., potting mix, coconut coir, hemp mats)
• Seeds
• Spray bottle

Instructions:

1. Soak seeds for several hours or overnight.
2. Fill the growing tray with moistened growing medium.
3. Sprinkle seeds evenly over the surface of the medium.
4. Gently press the seeds into the medium.
5. Mist the seeds with water using a spray bottle.
6. Cover the tray with a lid or another tray to create a dark, humid environment.
7. Place the tray in a warm location (around 20-25°C or 68-77°F).
8. Once the seeds have germinated (usually within 1-3 days), remove the cover and provide adequate light.
9. Water regularly, keeping the growing medium moist but not waterlogged.

2. Hydroponic System

Hydroponic systems grow microgreens without soil, using nutrient-rich water solutions. This method can result in faster growth and higher yields but requires more initial investment and technical knowledge.

Types of Hydroponic Systems:

• Deep Water Culture (DWC): Roots are suspended in a nutrient solution that is aerated with an air pump.
• Nutrient Film Technique (NFT): A shallow stream of nutrient solution flows continuously over the roots.
• Ebb and Flow (Flood and Drain): The growing tray is periodically flooded with nutrient solution and then drained.

Materials (Example: DWC):

• Plastic tub or container
• Net pots or seedling trays
• Air pump and air stone
• Hydroponic nutrient solution
• Seeds
• Clay pebbles or rockwool cubes

Instructions (Example: DWC):

1. Soak seeds for several hours or overnight.
2. Fill the plastic tub with nutrient solution.
3. Place the air stone in the tub and connect it to the air pump.
4. Fill the net pots with clay pebbles or rockwool cubes.
5. Sow the seeds in the net pots.
6. Place the net pots into the holes of a lid or floating platform that sits on top of the nutrient solution. The bottom of the net pots should just touch the nutrient solution.
7. Provide adequate light.
8. Monitor the nutrient solution levels and pH regularly.

3. Vertical Farming System

Vertical farming systems maximize space by stacking growing trays vertically. This is a great option for those with limited floor space or for commercial operations seeking to increase production. These systems can range from simple shelves to complex automated setups.

Materials:

• Shelving unit or vertical frame
• Growing trays and drainage trays
• Growing medium (or hydroponic system components)
• Grow lights (LED recommended)
• Seeds
• Watering system (manual or automated)

Instructions:

1. Assemble the shelving unit or vertical frame.
2. Place the growing trays on each shelf.
3. Fill the trays with growing medium (or set up the hydroponic system).
4. Sow the seeds.
5. Install grow lights above each shelf.
6. Water regularly (or set up the automated watering system).

Choosing the Right Growing Medium

The growing medium provides support, nutrients, and moisture to the microgreens. Several options are available, each with its own characteristics:

• Potting Mix: A readily available and affordable option, but make sure it's specifically formulated for seed starting. Avoid mixes with large chunks of bark or added fertilizers.
• Coconut Coir: A sustainable and environmentally friendly option made from coconut husks. It retains moisture well and provides good aeration.
• Hemp Mats: A biodegradable and compostable option made from hemp fibers. Hemp mats are easy to use and provide excellent support for microgreens.
• Rockwool: An inert growing medium made from molten rock. It has excellent water retention and aeration but can be more expensive.
• Peat Moss: While a popular option, peat moss is not sustainable due to its extraction from fragile peat bogs. Consider using alternatives.

The best growing medium for you will depend on your preferences, budget, and the specific needs of the microgreen varieties you're growing.

Lighting for Microgreens

Adequate lighting is crucial for healthy microgreen growth. While natural sunlight can work, it's often not sufficient, especially during winter months or in indoor environments. Artificial grow lights are highly recommended.

Types of Grow Lights:

• LED Grow Lights: The most energy-efficient and long-lasting option. LEDs provide a broad spectrum of light that is ideal for plant growth.
• Fluorescent Grow Lights (T5 or T8): A more affordable option than LEDs, but they consume more energy and have a shorter lifespan.
• High-Intensity Discharge (HID) Lights: Powerful lights that are suitable for large-scale operations, but they generate a lot of heat and require more energy.

Lighting Recommendations:

• Light Spectrum: Choose grow lights with a broad spectrum, including both blue and red wavelengths.
• Light Intensity: Microgreens typically require moderate light intensity. Aim for around 10-20 watts per square foot.
• Light Duration: Provide 12-16 hours of light per day.
• Distance from Plants: Keep the lights a few inches above the microgreens to avoid burning them.

Watering and Humidity

Proper watering is essential for microgreen growth. The growing medium should be consistently moist but not waterlogged. Overwatering can lead to fungal diseases, while underwatering can stunt growth.

Watering Techniques:

• Spray Bottle: Use a spray bottle to mist the microgreens regularly, especially during the early stages of growth.
• Bottom Watering: Pour water into the drainage tray and allow the growing medium to absorb it from the bottom. This helps prevent fungal diseases.
• Automated Watering Systems: For larger-scale operations, consider using an automated watering system to ensure consistent moisture levels.

Humidity:

Microgreens thrive in humid environments. Aim for a humidity level of 50-70%. You can increase humidity by:

• Covering the trays with a lid or humidity dome during germination.
• Using a humidifier in the growing area.
• Misting the microgreens regularly.

Nutrients for Microgreens

While microgreens don't require as many nutrients as mature plants, providing them with a balanced nutrient solution can enhance their growth and flavor. This is especially important for hydroponic systems.

Nutrient Solutions:

• Commercial Hydroponic Nutrient Solutions: These solutions are specifically formulated for hydroponic growing and contain all the essential nutrients in the correct proportions.
• Organic Nutrient Solutions: Options like seaweed extract or fish emulsion can provide organic nutrients to your microgreens.

Nutrient Application:

• Start with a dilute nutrient solution and gradually increase the concentration as the microgreens grow.
• Monitor the microgreens for signs of nutrient deficiencies, such as yellowing leaves or stunted growth.
• Adjust the nutrient solution accordingly.

Choosing Microgreen Seeds

The quality of the seeds is crucial for successful microgreen production. Choose seeds that are specifically labeled for microgreen growing or sprouting. These seeds are typically untreated and have a high germination rate.

Popular Microgreen Varieties:

• Radish: Spicy and fast-growing.
• Sunflower: Sweet and nutty flavor.
• Pea Shoots: Tender and sweet.
• Broccoli: Mild and nutritious.
• Arugula: Peppery and flavorful.
• Mustard: Pungent and spicy.
• Beet: Earthy and colorful.
• Cilantro: Fresh and aromatic.
• Basil: Sweet and fragrant.

Experiment with different varieties to find your favorites and cater to your customers' preferences.

Harvesting Microgreens

Microgreens are typically harvested when they have developed their first set of true leaves (the second set of leaves after the cotyledons). Harvesting too early can result in lower yields and less flavor, while harvesting too late can lead to tough and bitter microgreens.

Harvesting Techniques:

• Scissors or Sharp Knife: Use a sharp pair of scissors or a knife to cut the microgreens just above the growing medium.
• Washing: Gently wash the harvested microgreens in cold water to remove any debris.
• Drying: Dry the microgreens thoroughly using a salad spinner or by patting them dry with a paper towel.

Troubleshooting Common Problems

Even with careful planning and execution, you may encounter some problems while growing microgreens. Here are some common issues and how to address them:

• Mold or Fungal Diseases: Caused by overwatering, poor ventilation, or contaminated seeds. Improve ventilation, reduce watering, and use a fungicide if necessary. Consider using a hydrogen peroxide solution (diluted) to combat mold.
• Damping Off: A fungal disease that causes seedlings to collapse and die. Use sterile growing medium, improve ventilation, and avoid overwatering.
• Leggy Growth: Caused by insufficient light. Provide more light or move the microgreens closer to the light source.
• Yellowing Leaves: Can be caused by nutrient deficiencies, overwatering, or underwatering. Adjust the watering and nutrient levels accordingly.
• Poor Germination: Caused by low-quality seeds, improper temperature, or insufficient moisture. Use high-quality seeds, maintain the correct temperature, and ensure adequate moisture.

Scaling Up Your Microgreen Operation

If you're interested in growing microgreens for commercial purposes, you'll need to scale up your operation. This involves increasing your growing space, investing in more efficient equipment, and developing a solid marketing strategy.

Key Considerations for Scaling Up:

• Space: Determine how much space you need to meet your production goals. Consider using vertical farming techniques to maximize space.
• Equipment: Invest in automated watering systems, efficient lighting, and climate control systems.
• Labor: Hire staff to help with planting, watering, harvesting, and packaging.
• Marketing: Develop a marketing plan to reach your target customers, such as restaurants, grocery stores, and farmers' markets.
• Regulations: Research and comply with all local and national regulations regarding food safety and agricultural practices.

Global Examples of Microgreen Operations

Microgreen farming is gaining popularity worldwide. Here are a few examples of successful microgreen operations in different countries:

• Urban Cultivator (Canada): Specializes in automated microgreen growing appliances for homes and restaurants.
• Farm One (USA): Operates vertical farms in urban areas, supplying restaurants with fresh microgreens and specialty produce.
• Infarm (Germany): Develops modular vertical farms for supermarkets and restaurants, allowing them to grow microgreens and other produce on-site.
• LettUs Grow (UK): Designs and builds vertical farming systems for commercial growers.
• Sustenir (Singapore): Operates indoor vertical farms that produce a variety of leafy greens and microgreens.

Conclusion

Building your own microgreen growing system is a rewarding experience that allows you to enjoy fresh, nutritious, and flavorful microgreens year-round. Whether you're a beginner or an experienced gardener, there's a system that's right for you. By following the tips and guidelines in this guide, you can create a thriving microgreen operation, contributing to a more sustainable and healthy food system. From basic tray setups to advanced hydroponic and vertical farming systems, the possibilities are endless. Embrace the world of microgreens and discover the joy of growing your own food!