How to Grow Microgreens in Aquaponics

Microgreens have quickly become a favorite among gardeners and chefs alike for their rich flavor, vibrant colors, and impressive nutritional content. These tiny, nutrient-dense plants pack a powerful punch in both taste and health benefits, making them a popular choice for salads, garnishes, and even smoothies. But what if you could grow your own fresh microgreens using one of the most sustainable methods available? That’s where aquaponics comes in.

Aquaponics, provides an efficient and eco-friendly way to grow a variety of crops, including microgreens. By harnessing the natural processes of an aquaponics system, you can cultivate healthy, organic microgreens year-round with minimal water usage and no chemical fertilizers.

In this blog, we will explore how to grow microgreens in aquaponics, from setting up your system to harvesting your first crop. Whether you’re new to aquaponics or an experienced gardener, this step-by-step guide will help you take advantage of this sustainable gardening technique to grow your own nutritious microgreens at home.

What are Microgreens?

Microgreens are the young, tender shoots of edible plants harvested just after the first true leaves develop, usually between 7 and 21 days after germination. They are not to be confused with sprouts (which are harvested much earlier) or baby greens (which are more mature). Microgreens are prized for their delicate textures, vibrant colors, and intense flavors, making them a favorite in both gourmet cooking and healthy home kitchens.

Though tiny, microgreens pack an impressive punch in terms of taste, often concentrating the flavor of their mature counterparts. For example, a small handful of microgreens from mustard seeds will taste significantly sharper than a fully grown mustard plant. They’re easy to grow in small spaces, making them a convenient and rewarding crop for home gardeners and commercial producers alike.

Nutritional Value and Health Benefits of Microgreens

Despite their small size, microgreens are nutritional powerhouses. Research shows that they can contain up to 40 times more vitamins, minerals, and antioxidants than their mature plant counterparts. Some of the key nutrients found in microgreens include:
1. Vitamins: High in vitamins A, C, E, and K, microgreens can contribute to eye health, immune function, skin protection, and blood clotting.
2. Minerals: Many microgreens are rich in essential minerals like potassium, magnesium, iron, and calcium, which support overall health, including muscle function and bone health.
3. Antioxidants: Microgreens are loaded with antioxidants, which help fight oxidative stress and may lower the risk of chronic diseases such as heart disease and certain cancers.
4. Phytonutrients: These compounds, such as sulforaphane in broccoli microgreens, have been linked to numerous health benefits, including cancer prevention and improved cardiovascular health.

Types of Microgreens Commonly Grown in Aquaponics

Some popular microgreen varieties that thrive in aquaponic systems include:

1. Kale:

A mild yet nutrient-dense microgreen, kale is rich in vitamins A, C, and K, as well as calcium and iron. Its delicate texture and mild flavor make it a versatile addition to salads, sandwiches, and smoothies.

2. Arugula:

Known for its peppery taste, arugula microgreens add a spicy kick to dishes. It grows quickly and is rich in vitamins A and C, calcium, and potassium.

3. Radish:

Radish microgreens have a sharp, spicy flavor similar to mature radishes. They’re rich in vitamins A, B, C, E, and K, as well as folate, which supports cell growth and metabolism.

4. Broccoli:

These microgreens are particularly rich in sulforaphane, a compound known for its potential cancer-fighting properties. They have a mild, fresh flavor and are packed with vitamins A, C, and K.

5. Basil:

Basil microgreens offer an intense, concentrated version of the herb's familiar aroma and flavor. They are an excellent source of vitamins A and K, as well as antioxidants like beta-carotene.

6. Cilantro:

With a distinctive citrusy, savory flavor, cilantro microgreens are a favorite in Mexican and Asian cuisines. They are high in vitamin K and known for their anti-inflammatory properties.

7. Mustard:

Mustard microgreens offer a bold, spicy flavor and are high in antioxidants and vitamins A, C, and K. They grow quickly in aquaponic systems and can be harvested within 10–12 days.

8. Pea Shoots:

Pea shoots are a popular microgreen due to their sweet, delicate flavor and versatility. They are high in vitamins A and C and are one of the taller microgreen varieties, making them easy to harvest. Pea shoots usually mature within 10–14 days.

These microgreens not only provide a range of flavors, from mild to spicy, but they also offer a rich variety of nutrients. Growing them in an aquaponics system ensures a consistent supply of clean, fresh, and nutrient-dense greens that can be harvested regularly for personal or commercial use.

Why Aquaponics is a Suitable System for Microgreens

Aquaponics offers several advantages for growing microgreens, making it an ideal method for this crop:

1. Low Space Requirements:

Microgreens are small, fast-growing plants that don’t require much space. They can be grown in a vertical or stacked arrangement in aquaponics systems, which helps maximize the use of limited space. This is particularly beneficial for urban gardeners or those with limited growing areas.

2. Fast Growth Cycle:

Microgreens have a short growth cycle, typically reaching maturity in 7 to 21 days. This aligns perfectly with aquaponics, where nutrients are continuously available, allowing the plants to grow quickly and consistently. The nutrient-rich water from the aquaponics system enhances plant growth, often resulting in faster harvests compared to traditional soil-based farming.

3. Sustainability:

Aquaponics is a water-efficient system, using up to 90% less water than traditional agriculture. This is particularly advantageous for growing microgreens, which already require minimal water. Since water is continuously recirculated, aquaponics supports a sustainable and environmentally friendly way to grow microgreens without overusing resources.

4. Consistent Nutrient Supply:

The constant flow of nutrient-rich water in an aquaponics system ensures that microgreens receive a steady supply of essential nutrients. This results in healthier plants with more robust flavors and nutritional content.

5. No Chemical Fertilizers:

Since aquaponics relies on fish waste as the primary nutrient source, there is no need for synthetic fertilizers. This means the microgreens are grown organically, free from chemicals and pesticides, which makes them more appealing to health-conscious consumers.

6. Continuous Production:

With aquaponics, microgreens can be grown year-round in a controlled environment. Whether grown indoors or outdoors, the system can operate regardless of weather conditions, providing a reliable and continuous supply of fresh, nutritious greens.

Setting Up Your Aquaponics System for Microgreens

Setting up an aquaponics system to grow microgreens is a manageable project. Here, we’ll cover the key factors to consider when building your system, from selecting the ideal fish species to choosing the best growing medium for microgreens.

A. Choosing the Right Fish Species for Your System

Choosing the right fish species is important for the health of your system, as different fish have varying temperature, water quality, and space requirements. Here are some commonly used fish for aquaponics systems:

1. Tilapia:

A popular choice due to their hardiness and adaptability, tilapia thrive in a range of water conditions and temperatures (usually 75°F–85°F). They are easy to care for, reproduce quickly, and grow rapidly.

2. Goldfish:

Ideal for small-scale or beginner systems, goldfish are inexpensive, easy to maintain, and can tolerate a wide range of water temperatures (60°F–75°F). Although they don’t grow as large as tilapia, goldfish are a good choice for ornamental systems and those focused solely on plant production.

3. Catfish:

Catfish prefer warmer water (70°F–85°F) and have a high tolerance for lower oxygen levels, making them well-suited for systems where oxygen fluctuations might occur.

4. Koi:

Koi fish are ornamental but can also contribute to aquaponics systems. They are robust, adaptable to colder temperatures (50°F–70°F), and have a long lifespan, making them a good option for aquaponics enthusiasts who also enjoy the aesthetic appeal of their fish.

5. Trout:

For those in cooler climates or systems that naturally maintain lower water temperatures (50°F–65°F), trout are a great option. However, they require well-oxygenated water and specific feeding regimens, making them more challenging to care for than tilapia or goldfish.

Designing a Space-Efficient Aquaponics System

Microgreens require minimal space to grow, making them ideal for space-efficient aquaponics designs. Here are a few setup ideas that maximize your growing area while ensuring your system is manageable:

1. Vertical System:

Vertical aquaponics systems allow you to grow multiple layers of microgreens in a small footprint, making it perfect for urban or indoor setups. By stacking grow beds or using tiered shelves, you can dramatically increase your growing capacity without needing a large amount of floor space.

2. Grow Beds (Media Bed System):

If you prefer a horizontal layout, shallow grow beds are ideal for growing microgreens. These beds can be placed on tables or shelves near your fish tank. When using grow beds, it’s essential to ensure adequate water flow and drainage. The grow beds should be no deeper than a few inches, as microgreens only require a shallow growing medium. 

3. Floating Rafts (Deep Water Culture):

Floating rafts are another efficient method of growing microgreens. In this system, plants grow on rafts that float directly on the water, with their roots submerged in nutrient-rich water. The rafts provide excellent access to nutrients and are easy to maintain. Microgreens thrive in this setup because of the continuous supply of water and nutrients.

Equipment Needed for Your Aquaponics System

To create a successful aquaponics system for microgreens, you’ll need specific equipment to ensure everything runs smoothly:

1. Grow Lights:

Microgreens need adequate light for photosynthesis, especially if you’re growing them indoors or in low-light conditions. Full-spectrum LED grow lights are the best option, as they provide the light wavelengths that plants need for optimal growth. Position the lights 6 to 12 inches above the microgreens and provide 12 to 16 hours of light per day.

2. Pumps:

A water pump is necessary to circulate water between the fish tank and the grow beds or floating rafts. The pump ensures the plants receive a steady supply of nutrient-rich water, while also keeping the water in the fish tank oxygenated and filtered.

3. Timers:

Timers can be used to automate the water circulation and lighting schedules, reducing the need for manual intervention. For example, you can set the grow lights to turn on and off at specific times.

4. Air Stones and Air Pumps:

To maintain adequate oxygen levels for both fish and plants, an air pump connected to air stones is essential. This aerates the water, promoting healthy root growth for the microgreens and ensuring the fish have enough dissolved oxygen to thrive.

5. Filters:

Depending on your system, mechanical and biological filters may be needed to keep the water clean. A mechanical filter will remove solid waste from the fish, while a biological filter will house the beneficial bacteria needed to convert ammonia into nitrates.

Choosing and Preparing Microgreen Seeds for Aquaponics

Selecting the right seeds and properly preparing them is a key step in successfully growing microgreens in an aquaponics system. Different microgreen varieties have unique flavors, growth rates, and nutrient profiles, so it's important to choose ones that will thrive in your setup. Additionally, ensuring your seeds are high-quality and preparing them for optimal germination will set your microgreens up for success.

A. How to Source High-Quality Seeds

The quality of your seeds is critical to the success of your microgreens. Low-quality seeds may have lower germination rates, contain contaminants, or be treated with chemicals, all of which can negatively impact your aquaponics system. Here’s our recommended microgreen seeds from Amazon.

1. Superfood Microgreen Seed Mix

A COLORFUL & DELICIOUS microgreen salad mix containing heirloom non-GMO microgreen seeds. 

2. Basic Salad Mix Microgreens Seeds

 

Basic Salad Micro Mix. A flavorful and colorful combination of microgreens that grow well together and can be harvested at 10 days. Contains: Broccoli, Kale, Kohlrabi, Arugula & Red Acre Cabbage.

3. Microgreens Seeds

Step-by-Step Guide to Planting Microgreens in Aquaponics

Once you've selected your microgreen seeds and prepared your aquaponic setup, it's time to plant and grow your microgreens. Below is a detailed guide to planting, optimal growing conditions, and tips to maintain a healthy aquaponics system.

1. Prepare the Grow Media:

In an aquaponics system, microgreens are typically grown in a shallow layer of grow media such as hydroton (clay pebbles). Ensure the grow media is evenly distributed across the grow bed or planting tray.

2. Pre-Soak the Seeds (If Necessary):

Certain seeds, like pea shoots and sunflowers, benefit from pre-soaking. If you are using these types of seeds, soak them for the recommended time before planting. For smaller seeds like kale or radish, you can skip this step and plant directly.

3. Spread Seeds Evenly Over the Growing Medium:

• Sprinkle the microgreen seeds evenly over the surface of the growing medium. Ensure that the seeds are spread densely, as microgreens grow best when crowded together.
• Avoid overlapping the seeds too much, as this can lead to mold or poor air circulation. For larger seeds like pea shoots, leave a small amount of space between each seed.
• You may need to lightly press the seeds into the growing medium to ensure good contact, but avoid burying them deep.

4. Cover the Seeds (Optional):

• Depending on the variety of microgreens and the grow media you are using, you can lightly cover the seeds with a thin layer of the media. For smaller seeds like broccoli or kale, this step is usually unnecessary.
• Alternatively, you can place a humidity dome or a plastic cover over the planting tray to retain moisture and promote germination.

5. Water the Seeds:

• In an aquaponics system, water is continuously circulated from the fish tank to the grow beds, so there’s no need to manually water the seeds once the system is up and running. However, during the germination phase, you may need to mist the seeds to keep them moist until they sprout.
• Ensure that the growing medium remains damp throughout the germination period, but not saturated. Too much water can lead to mold or seed rot.

6. Monitor for Germination:

Depending on the variety of microgreens, germination can take anywhere from 2 to 5 days. During this time, keep the seeds in a dark, warm place or under a humidity dome to create optimal conditions for sprouting.

Optimal Light and Temperature Conditions

Once the seeds have germinated and begun to sprout, light and temperature become key factors in their growth.

1. Light Requirements:

• Microgreens need ample light to grow strong and healthy. Full-spectrum LED grow lights are ideal for indoor aquaponics systems, as they mimic natural sunlight and provide the right wavelengths for plant growth.
• Position the grow lights about 6–12 inches above the microgreens to ensure they receive sufficient light. They should receive around 12–16 hours of light per day for optimal growth. Use a timer to automate the lighting schedule.
• If growing microgreens outdoors or in a greenhouse, ensure they get indirect sunlight, as too much direct sun can cause them to wilt or become scorched.

2. Temperature Conditions:

• Microgreens generally thrive in temperatures between 65°F and 75°F (18°C–24°C). This range provides optimal conditions for rapid growth without stressing the plants.
• Avoid placing the system in areas with extreme temperature fluctuations, as this can slow growth or cause stress to the plants and fish. In colder climates, you may need a heater to maintain the water temperature for both the fish and plants.

3. Humidity Levels:

Microgreens prefer moderate humidity, around 40–60%. High humidity can encourage mold growth, while too little can cause the plants to dry out. Use a fan to maintain airflow and prevent excess moisture buildup.

Managing Water and Nutrient Flow

In aquaponics, managing the water and nutrient flow correctly is crucial to ensuring that both the fish and plants thrive.

1. Water Circulation:

• The water pump should be set to cycle water from the fish tank to the grow beds at regular intervals. This provides the plants with nutrient-rich water from the fish waste, which contains nitrogen, phosphorus, and other essential nutrients.
• Ensure that the grow bed drains properly between cycles to prevent waterlogging the roots. The grow media should stay moist but not flooded.

2. pH Levels:

• The pH level of the water should be kept between 6.0 and 7.0 for optimal plant growth and fish health. Microgreens generally prefer a slightly acidic to neutral pH.
• Regularly test the pH of your system and adjust as needed. If the water becomes too acidic or too alkaline, it can harm both the fish and the plants. Adding natural pH adjusters like lime or vinegar can help maintain balance.

Tips for Maintaining a Healthy Balance in Your Aquaponics System

1. Fish Health:

• Keeping your fish healthy is essential for maintaining the nutrient cycle. Ensure the fish are fed a balanced diet and monitor water quality regularly to avoid ammonia buildup or oxygen depletion.
• Regularly clean the fish tank and filters to prevent waste buildup. If the system becomes clogged, it can reduce the flow of nutrients to your plants.

2. Preventing Mold and Disease:

• Overcrowding and high humidity are common causes of mold and disease in microgreens. Ensure there is enough space between plants for airflow, and use a fan to maintain air circulation.
• Check your microgreens regularly for any signs of mold or disease. If you spot mold, remove the affected plants immediately and adjust the humidity levels or airflow to prevent it from spreading.

3. Harvesting at the Right Time:

• Microgreens are typically ready for harvest 7–21 days after planting, depending on the variety. Most microgreens should be harvested when they reach about 1–2 inches in height and before they develop true leaves (the second set of leaves).
• Use clean scissors to cut the microgreens just above the growing medium, taking care not to damage the remaining plants.

4. Replanting and Rotating Crops:

• Once you’ve harvested your microgreens, you can clean the growing medium and replant immediately. This ensures a continuous cycle of fresh microgreens.
• Rotating different varieties of microgreens can help maintain balance in the system and prevent nutrient depletion from growing the same crop repeatedly.

5. Harvesting Microgreens

Harvesting microgreens at the right time and with proper techniques ensures you get the best flavor, nutrition, and yield from your aquaponic system. While microgreens are usually harvested once, there are some methods that can help you maximize regrowth and potentially get multiple harvests from the same crop.

When to Harvest Microgreens:

1. Timing:

• Most microgreens are ready to be harvested 7–21 days after planting, depending on the variety. Generally, they should be harvested when the first true leaves (cotyledons) have fully opened, but before the second set of true leaves develop. Harvesting at this stage ensures optimal flavor, texture, and nutrition.
• Common microgreens like radish, kale, and broccoli are often ready to harvest in about 7–14 days, while slower-growing varieties like basil or cilantro may take closer to 14–21 days.

2. Size:

• The ideal height for harvesting microgreens is usually between 1 and 3 inches tall. For larger microgreens, like pea shoots, you may want to wait until they are closer to 4–6 inches in height.
• Inspect the microgreens regularly to ensure you harvest them before they become too mature. If they are left to grow too long, they may develop bitter flavors, tougher stems, or lose some of their nutrient density.

3. Signs They Are Ready:

• Bright, vibrant colors in the leaves and stems.
• Firm, healthy stems that stand upright without wilting.
• First true leaves (cotyledons) are open and visible.
• A mild, fresh scent, without signs of yellowing, mold, or disease.

How to Harvest Microgreens

1. Tools Needed:

• Sharp, clean scissors or a knife.
• A shallow tray or basket for collecting the harvested microgreens.
• A clean, dry cloth or paper towel for handling and storing the greens.

2. Harvesting Technique:

• Step 1: Prepare Your Workspace: Before harvesting, clean your scissors or knife with water and a mild disinfectant to prevent contamination. Lay a clean tray or basket next to your grow bed for collecting the harvested greens.
• Step 2: Hold the Microgreens: Gently gather a small bunch of microgreens by holding them at the base, near the growing medium, without pulling on the roots.
• Step 3: Cut Above the Growing Medium: Using your clean scissors or knife, cut the microgreens just above the surface of the growing medium, taking care not to pull out or disturb the roots. Cut in a smooth, swift motion to avoid crushing the stems.
• Step 4: Avoid Damaging Remaining Greens: Be mindful not to damage or uproot surrounding microgreens during the harvest. Work in small sections, cutting only what you plan to use immediately.

3. Batch Harvesting

If you're not using all your microgreens at once, you can opt for batch harvesting. This allows you to extend the harvest window by cutting small sections at a time over several days. However, be sure to monitor your microgreens closely, as they may begin to deteriorate or bolt (go to seed) if left too long after maturity.

Common Challenges and Troubleshooting  of Growing Microgreens in Aquaponics

Growing microgreens in an aquaponics system offers many benefits, but like any gardening practice, it can come with challenges. Understanding how to address common problems such as mold, pests, and nutrient deficiencies, as well as maintaining water quality and fish health, will help you optimize your system and ensure consistent, healthy growth.

1. Mold and Fungal Growth

• Problem: Mold is one of the most common issues in microgreen cultivation, especially in humid environments like aquaponics. Mold thrives in high humidity and poor air circulation, which can quickly spoil your crop.

• Solutions:
• Improve Airflow: Ensure adequate ventilation around your grow beds or trays. Using a small fan to circulate air can help reduce humidity and prevent mold growth.
• Monitor Humidity: Keep the humidity level between 40% and 60%. If you notice the air is too moist, reduce it by adjusting your ventilation system or using a dehumidifier.
• Avoid Overwatering: In an aquaponics system, overwatering is less of a concern since water is constantly cycled. However, ensure the growing medium is not too saturated. Proper drainage and avoiding waterlogged conditions help prevent mold.
• Spacing: Plant seeds densely but ensure there’s enough space for airflow between them. Overcrowding can trap moisture and increase the likelihood of mold.

2. Pests

• Problem: While microgreens are generally less prone to pest infestations due to their short growing cycle, pests like aphids, fungus gnats, or whiteflies can occasionally appear in an aquaponics setup.

• Solutions:
• Improve Airflow: Ensure adequate ventilation around your grow beds or trays. Using a small fan to circulate air can help reduce humidity and prevent mold growth.
• Monitor Humidity: Keep the humidity level between 40% and 60%. If you notice the air is too moist, reduce it by adjusting your ventilation system or using a dehumidifier.
• Avoid Overwatering: In an aquaponics system, overwatering is less of a concern since water is constantly cycled. However, ensure the growing medium is not too saturated. Proper drainage and avoiding waterlogged conditions help prevent mold.
• Spacing: Plant seeds densely but ensure there’s enough space for airflow between them. Overcrowding can trap moisture and increase the likelihood of mold.

3. Nutrient Deficiencies

• Problem: Although aquaponics systems provide a natural source of nutrients from fish waste, deficiencies can still occur, especially in a fast-growing crop like microgreens. Common signs include yellowing leaves (nitrogen deficiency), slow growth, or stunted plants.
• Solutions:

• Check Fish Feeding: Ensure your fish are being fed adequately. If fish waste production is low, there might not be enough nutrients for your plants. Increase the fish feed slightly if needed.
• Balance the Fish Stock: Maintain an appropriate balance between the number of fish and the plants. Too many fish can lead to excessive nutrient buildup, while too few fish can lead to nutrient shortages.
• Supplement with Nutrients: If nutrient levels are consistently low, you can supplement with organic nutrient solutions designed for aquaponics, like iron or potassium, without disrupting the ecosystem.

4. Maintaining Water Quality 

• Problem: Poor water quality can stress fish and reduce nutrient availability for plants. Common water quality issues include high ammonia, low oxygen, or imbalanced pH.

• Solutions:
• Monitor Water Parameters: Regularly test the water for ammonia, nitrite, nitrate, and pH levels. Ideal pH for aquaponics is between 6.8 and 7.0, and ammonia should always be kept below 0.5 ppm to avoid harming fish and plants.
• Aeration: Ensure the water is well-aerated. Use air pumps or air stones to maintain sufficient oxygen levels, especially for the fish.
• Water Changes: Perform partial water changes if ammonia or nitrate levels become too high. Changing 10–20% of the water weekly can help maintain balance in your system.

5. Fish Health

• Problem: Stress or disease in fish can disrupt the entire system, as unhealthy fish produce fewer nutrients, and a lack of nutrients can, in turn, weaken the plants. Signs of unhealthy fish include lethargy, erratic swimming, or visible infections.

• Solutions:

• Feed Fish a Balanced Diet: Ensure the fish are receiving high-quality feed, rich in nutrients. Healthy fish produce nutrient-rich waste that supports plant growth.
• Maintain Consistent Water Temperature: Fish are sensitive to temperature changes. Ensure the water temperature is appropriate for your species of fish (typically between 68°F and 86°F, depending on the type of fish).
• Quarantine New Fish:When introducing new fish to the system, quarantine them in a separate tank for a few weeks to ensure they are disease-free before adding them to your main aquaponics system.

Conclusion

Growing microgreens in an aquaponics system presents a unique and compelling opportunity for sustainable, efficient, and high-quality cultivation. By leveraging the natural synergy between fish and plants, aquaponics offers a range of benefits that align with modern ecological and dietary needs.

Furthermore, the fast growth cycle of microgreens, coupled with the ability to produce crops year-round in a controlled environment, allows for a consistent and As you embark on your aquaponics journey, remember that this method offers more than just a way to grow fresh greens; it provides a pathway to a more sustainable and interconnected way of cultivating food, connecting with nature, and contributing to a healthier planet.