One of the benefits of aquaponics is that you can grow just about any plants such as lettuce, spinach, carrots, fruiting plants like tomatoes and strawberries, and even herbs and flowers. Plants can be grown from seeds to seedlings and planted into your grow beds, floating boards, or pvc pipes.
Planting in aquaponics can be very simple. In most ways, you can treat it as you would a traditional garden bed. However, there are a few basic things you need to know before you start planting in your aquaponic garden.
The Difference Between Traditional Planting And Aquaponics
- Traditional planting uses fertilizer for intensive in ground cultivation. Aquaponics uses fish wastes as fertilizer for the plants to grow in contained growing media.
- The water used in aquaponics is much lower than in traditional plant cultivation. Aquaponics uses only about 10 percent of the water needed to grow the same plant in soil.
- Traditional planting requires extensive land areas, while aquaponics does not need extensive areas of land to set up. You can set up an aquaponics system in basements, rooftops, garage, or in a small backyard.
- Aquaponics planting is year-round, so it has a higher yield compared to traditional planting.
Source Of Nutrients For Aquaponics Plants
In aquaponics, nitrogen is supplied to plants in nitrate, converted from the ammonia of fish wastes through bacterial nitrification. The solid wastes are broken down by heterotrophic bacteria to release the essential nutrients into the water.
It is essential to feed the fish a balanced and complete diet to ensure that plants will not suffer from nutrient deficiencies. However, sometimes a perfectly balanced aquaponics system may become deficient in specific nutrients, like iron, potassium, or calcium deficiencies. This is because feed pellets are a complete food for the fish, but not necessarily everything needed for plant growth. Fish do not need the same amount of iron, potassium, and calcium that the plants require. This is why nutrient deficiencies in aquaponics systems occur.
Nutrient deficiencies can be problematic for plant production, but there are solutions available. If an iron deficiency occurs, iron can be added as chelated iron, while calcium and potassium are added when buffering the water to correct the pH. These are added as calcium hydroxide or potassium hydroxide or as calcium carbonate and potassium carbonate.
What And When To Grow In Aquaponics
Different plants grow under different conditions. In growing plants in your aquaponics system, it is essential to consider what type of grow bed you're using. Some plants can thrive and grow in a floating raft, like lettuce and leafy greens, while root vegetables and fruiting plants grow better in media beds.
When deciding what plants to grow in your aquaponics system, it is important to choose varieties of vegetables that will grow best in your climate. Temperature is hard to control, even if you're growing in a greenhouse, and plants thrive better when the temperature matches their normal habitat. So grow cold-weather crops in colder months and warm-weather crops during summer.
It is best to plant a mixture of vegetables in your aquaponics system. Plant some fast-growing plants like lettuce and slow-growing plants such as herbs, tomatoes, peppers, and dark leafy greens like kale and swiss chard. Using succession planting allows some of your plants to mature and be harvested while the newer ones are growing and coming in behind. Succession planting will ensure that you always have plants taking nutrients from the water all the time.
Important Considerations Before Planting
- Planting Design: The layout of your grow bed will maximize your plant production in the available space. Before planting, choose wisely what plants you will grow, bearing in mind the space needed by each plant. Arrange your plants as you plant them in your grow bed, considering their nutrient demand, physical compatibility, and ease of access. A good practice is to plan the layout of your grow beds on paper to have a good understanding of how everything will look.
- Plant Diversity: Plants are susceptible to diseases and parasites. If only one crop is grown, the chance for severe infestation is higher, which can unbalance the whole aquaponics system. That is why planting a diverse range of plants is encouraged.
- Staggered Planting:It is important to stagger planting so that there can be constant harvest and replanting, which will help maintain the balance of nutrient levels in the system. Staggered planting also provides a steady supply of plants on the table.
- Maximize Your Grow Bed Space:Maximize the surface area of your grow bed and the vertical space and time. For example, plant vegetables with short grow-out periods like salad green between plants with longer-term like eggplants or tomatoes. The benefit of this practice is that you can harvest the salad greens while providing more room for the eggplants to mature.
How to Germinate Seeds
All seeds need water, oxygen, and proper temperature to germinate. When the seed is exposed to the appropriate condition, water and oxygen are taken through the seed coat. Then the embryo's cells will enlarge, and the seed coat will break open for the root to emerge, followed by the shoot that contains leaves and stems.
Some seed coats are so hard that water and oxygen can only get through when the coat breaks down. Soaking or scratching the seeds will help break down the seed coat and help the seed germinate faster. Over-watering and not enough oxygen, planting seeds too deeply, and dry conditions can cause poor germination.
Seed Starting Techniques
Below are the three major ways of starting seeds in Aquaponics.
1. Direct Sowing
Some seeds can be sown directly in your grow beds. This method is used in a media-based system, where the grow media like pebbles or gravel will provide support to the seed growth.
Spread the seeds out evenly, push them down under the top dry layer of your growing media, and then wait for it to germinate naturally. This method works well for leafy greens and herbs like lettuce and chard. However, some seeds germinate better than others under these conditions, so you need to sow many seeds expecting not all of them will germinate.
The advantage of the direct sowing method is that you need not transplant your plants to your grow bed, eliminating the possibility of damaging the plants' roots.
2. Starter Plugs
Starting seeds in a separate media plug and placing it to your grow bed is a great way to arrange your plants in your grow bed. Using starter plugs is best used for seeds that are harder to germinate or need more time and care like tomatoes, peppers, and eggplant. Once the seeds germinate to your desired size, they can be transferred into your grow bed by making a small hole and gently placing the seedling in it. Then carefully cover the plug with your grow media.
There are different starter plugs, such as rock wool or peat. Compressed peat, rock wool, and paper towels are the most common because they are inexpensive, sterile, and easy to find.
3. Cuttings and Cloning
Some plants can be grown in Aquaponics by sticking cuttings directly into your grow bed. Fast-growing herbs like basil and mint will sprout from cuttings, making them a great way to plant without using seedlings. Rooting hormones that induce new roots can be used by dipping the cut end into the rooting hormone.
You can get seedlings from a store or start seeds yourself. Once your seeds sprout, good soil and strong light will help them grow. When transplanting your seedlings from the soil, fill a small container with water, and gently rinse the dirt off the roots before placing the plant in the media deep enough for the roots to touch the water. Applying rooting compounds can help because the transplanting process can sometimes damage the plant's roots. The rooting compound will encourage fast regrowth.
Growing Guidelines for 5 Common Aquaponics Plants
pH: 6.0 - 7.0
Plant spacing: 18 - 30cm
Germination time: 24 - 32 days
Temperature: 15 - 22 °C
Plant height and width: 20 - 30 cm; 25 - 35 cm
Growing Instruction: Seedlings can be transplanted in your grow bed at three weeks when plants have at least 2-3 real leaves. You can add phosphorus supplement fertilizer to the seedlings in the second or third week to avoid plant stress during transplant.
When transplanting lettuce in a colder climate, expose your seedlings to the colder temperature and direct sunlight for 3-5 days for a higher survival rate. When transplanting in warm weather, place a light sun-shade over the plants for 2-3 days to avoid plant stress.
To achieve crisp, sweet lettuce, maintain a high nitrate level in your system. If you're growing in a grow bed, plant new lettuce where the taller plants will partially shade them.
Harvesting:You can harvest as soon as the heads or leaves are large enough to eat. It is best to harvest early in the morning when the leaves are crisp and full of moisture and chill quickly to maintain freshness.
pH: 6 - 7.5
Plant Spacing: 30 - 30 cm
Germination time and temperature: 4-5 days; 25 - 30 °C
Growth time: 25 - 35 days
Temperature: 16 - 24 °C
Light exposure: full sun (partial shade for temperatures > 26 °C)
Growing Instruction: Swiss chard seeds produce over one seedling, so it is essential to do thinning as seedlings grow. As plants grow, older leaves can be removed to encourage new growth.
Harvesting: Swiss chard leaves can be cut continuously when they reach harvestable size. Removing larger leaves encourages new growth.
pH: 6 - 7
Plant Spacing: 15 - 30 cm
Germination time and temperature: 8-10 days; 20 - 25 °C
Growth time: 20 - 30 days after transplant
Temperature: 15 - 25 °C
Light exposure: partial shade at >25 °C
Growing instructions: Initial germination can be difficult when growing parsley, which can take 2-5 weeks. To speed up germination, you can soak the seeds in warm water (20-23 °C) for 24-48 hours to soften the seed husks. After soaking, drain the water and sow seeds into propagation trays. After 5-6 weeks, transplant the seedlings into your grow bed.
Harvesting: Harvesting begins once individual stalks of the plant are at least 15 cm long. Harvest the outer stems from the plants to encourage growth. Parsley dries and freezes well.
pH: 5.5 - 6.5
Plant spacing: 40 - 60 cm
Germination time and temperature: 4-6 days; 20-30 °C
Growth time: 50 - 70 days until the first harvest, fruiting 90-120 days up to 8-10 months
Temperature: 13 - 26 °C at night; 22-26 °C day
Light exposure: full sun
Growing Instruction: Transplant seedlings into your grow bed 3-6 weeks after germination when the seedlings are 10-15 cm. Use stakes or plant support in transplanting to prevent root damage. In transplanting your seedlings, avoid water-logged conditions around the plant collar to reduce the risk of any diseases. Once your tomato plant is about 60 cm tall, you can prune the unnecessary upper branches and remove the leaves from the main stem's bottom to favor air circulation and reduce fungal incidence. You can also remove the leaves that cover each fruit branch before the fruits ripen to favor nutrition flow to the fruits and speed up maturation.
Harvesting:Harvest your tomatoes when they are firm and fully colored for better flavor, as the fruit will continue to ripen after harvest.
pH: 5.5 - 6.5
Plant spacing: 30 - 60 cm
Germination and temperature: 8 - 12 days; 22-30 °C (seeds will not germinate below 13 °C)
Growth time: 60 - 95 days
Temperature: 14 - 16 °C
Light exposure: full sun
Growing Instruction: Transplant seedlings with 6-8 true leaves. You can use stakes or vertical strings hanging from iron wires to support bushy or heavy-yielding plants. For red sweet peppers, leave the green fruits on the plants until they ripen and turn red. Reduce the number of flowers in excessive fruit settings to favor the growing fruits to reach adequate size.
Harvesting: Harvest your peppers when they are large enough to be harvested. To improve your plant's vitamin C level, leave peppers on the plants until they ripen fully by changing color. Peppers can be stored fresh or dried.
Plants are one of your aquaponics system's main components, so it is essential to take care of them. Plants filter the water in your system and provide food to you and your family. The fun part of gardening is experimenting and learning, so don't worry if you make mistakes on the way because it's all part of the process. Once