The worst plants you can use for aquaponics depend on your system, setup size or capacity, skills, experience, expectations, and climate. In practice, you can’t grow every plant or crop you want due to a few unconquerable limitations. So, what are the worst plants for aquaponics?
Here’s a list of the 12 worst plants you can use for aquaponics:
- Melons
- Some cruciferous veggies
- Corn
- Sweet potatoes
- Mint
- Ginger
- Potatoes
- Onions
- Berries
- Grapes
- Fruit trees
- Many flowers
Some of these plants are unsuitable for an aquaponic system, but quite a few can grow rather well. However, the high levels of effort and complications involved make these the worst plants you can use for aquaponics. Keep reading to know the reasons why you should avoid these plants.
1. Melons
Melons are incredibly slow and difficult to grow, not only in an aquaponic system but also conventionally. Two fundamental benefits of aquaponics are organic farming and an almost self-contained or cyclical ecosystem. Melons don’t serve either purpose in most scenarios.
All melons are nutrient hogs, and you have to use a lot of fertilizer or supplement throughout the growing phase. The early growth stage requires more nitrogen, which isn’t a problem if you have sufficient fish stock in the tank, but you need adequate phosphorus and potassium later.
Also, you need to regulate the water flow and provide ample space. Furthermore, melons are vulnerable to various diseases. The tedious effort necessary despite an uncertain outcome or yield isn’t an ideal or even a desirable scenario for those still getting familiar with aquaponics.
2. Some Cruciferous Veggies
Aquaponics is excellent for a few cruciferous vegetables. You can grow kale, watercress, and bok choy almost effortlessly, but not broccoli and cauliflower.
Broccoli and cauliflower need larger setups, not only for the growing media or beds but also for the fish tank and stock. Also, you need to balance nitrogen availability with phosphorus and potassium for the desired growth.
One significant problem people encounter is enormous vegetative growth with little or no fruit. So, your broccolis and cauliflowers may develop a lot of leaves due to excess nitrogen in the growing media. The flower will be small, or you may not have one in a few plants.
Watch this YouTube video showing excessive vegetative growth:
Furthermore, many cruciferous vegetables need a balance of sunlight and shade. While they must be in direct sunlight for at least six hours or grow lights for longer, excessive heat damages the plant, especially the bud. If you’re a beginner in aquaponics, you should avoid these veggies.
Broccoli and other plants in the same family grow well in slightly acidic media, a pH of around 6.0 to 6.5. Generally, aquaponic systems have a pH level above 6.5 and closer to 7.0. You may still consider growing these plants, but they’ll take up a lot of space with uncertain returns.
You may grow cruciferous vegetables for their leaves, but the fruits are seasonal and need specific settings, such as exposure to sunlight and heat, shade availability, and nutrients. Besides, broccoli and cauliflower don’t grow identically in the same setting, so your situation can be demanding.
3. Corn
You can’t grow corn in a new aquaponics system. There aren’t sufficient nutrients in a new ecosystem to feed a greedy crop like corn.
All aquaponics systems need time to mature, regardless of the type of growing media, bed, and other variable factors. And, you can’t grow corn in any random setting. Corn takes more than three months to mature for harvest.
You may consider corn if you have a mature aquaponics system like the one in this YouTube video:
Aquaponics isn’t designed as a system in practice to include all the elements of typical farming, such as fertilizers, insecticides, and pesticides. Thus, food crops, fruiting vegetables, and flowering veggies aren’t appropriate options unless you want to opt for a hybrid system.
Tomatoes, peas, cabbage, cauliflower, and zucchini attract various troublesome pests. Corn isn’t particularly vulnerable to pests, but it attracts many insects, and you may have a crisis at your farm.
The entire objective of operating an organic farm becomes difficult when you have to resort to chemicals and other means to counter the numerous insects, pests, and infestations.
4. Sweet Potatoes
Sweet potatoes take around four months to mature for harvest. You may not want such a long growing cycle.
Nonetheless, the more important fact is the required acidity of the growing media. Sweet potatoes need soil or growing media in the pH range of 5.5 to 6.5. Some varieties require a much more acidic growing media bed, so you may need a pH level of 5.5 or less.
Aquaponics systems can’t have such a highly acidic water channel. A pH lower than 6.5 will weaken most bacteria in the growing beds and media. A pH level of 6 may kill or neutralize Nitrosomonas, Nitrobacter, microbes, and worms. Also, highly acidic water will kill the fish stock.
One of the inevitable challenges of tubers or any crop that grows underground is the deceitful growth of the shoots. Sweet potatoes, for example, may develop long and winding vines in an aquaponics system. You may find the plant outgrowing its media bed and spreading further.
The visible growth may encourage you to think that the plant is poised for a bountiful harvest. However, these leaves, stems, and nodes don’t mirror the actual growth of the tubers in the bed, even if it’s a wicking system. The reality is often the exact opposite, thus disappointing.
5. Mint
Aquaponics is favorable to a plethora of herbs, including chives, fennel, and parsley, although they can grow quickly and take over a grow bed or vertical tower. This sprawling issue is also relevant to mint. While chives, fennel, and parsley are manageable, mint can be beyond control.
If you’re new to aquaponics and want a self-running system, you may want to avoid mint. Those proactive with any aquaponics system, spending sufficient time on upkeep, and willing to put in the extra effort to manage mint can definitely give it a try. Otherwise, consider easier plants.
6. Ginger
Ginger poses multiple challenges, making it unsuitable for aquaponics systems. You need to invest around ten months for ginger plants to mature completely, or you have to opt for a partial harvest. Also, you must provide calcium supplements and maintain a pH level of 5.5 to 6.5.
What’s more, ginger tends to spread or sprawl. You’ll find leaves and shoot growth taking over a large section of a grow bed without much of the ginger to harvest.
If you can spare a lot of space without hampering other plants, you may dismiss this issue. Otherwise, you’ll have a significantly reduced net return with ginger, be it yield or utilization of your aquaponics system.
7. Potatoes
Aquaponics is a water-based growing system. While potatoes need optimum water to grow and develop, excess accumulation of moisture in the soil or growing media will cause blight.
You may have a flood and drain system or a wicking setup. All such systems have their disadvantages that may not lead to the desired yield, and this truth also applies to other rooting vegetables.
Aquaponics enthusiasts grow carrots and radishes in different setups, such as rafts and wicking media. The results are usually far from desirable on rafts. More often than not, carrots, radishes, and other stems, bulbs, or tubers don’t grow and develop as you may expect in theory.
The only aquaponics system that can even remotely be viable for potatoes is a wicking bed. A wicking bed system isn’t easy, nor is it readily scalable. Also, you’ll need all the essentials of traditional farming or gardening, from the potting mix or composting soil to fertilizers, etc.
8. Onions
Onion isn’t suitable for aquaponics systems. Rafts and vertical towers aren’t even in consideration for onions. A wicking bed or growing media is workable, but the steep challenges make it nearly impossible to get the kind of onions that you want to harvest and actually use.
First, onions don’t grow well in soggy media. Thus, a growing media bed is out of the question.
Second, you must stop watering onion plants for one or two weeks before the harvest. Otherwise, the onions will rot. So, you need to put in much more effort and make special wicking beds. It’s much easier to grow kale, chard, and other such leafy vegetables in aquaponics than onions.
9. Berries
Almost all berries are a nonstarter in almost every aquaponics system. The only exception is strawberry, but it’s not a cakewalk to grow and nurture in aquaponics. Blueberry, cranberry, gooseberry, and elderberry require a moderately to reasonably high acidic growing media.
Raspberry and strawberry prefer acidic growing media, too. You may still have some luck with raspberry in a growing media of 6.5 or up to 7.0 on the pH scale. However, most of the other berries won’t grow or develop much at any pH level above 6.5, including strawberries.
Additionally, there’s the nutrient-deficiency problem you’re likely to encounter in aquaponics, irrespective of the system. Take iron, for instance. A pH level of nearly 7.0 depletes the iron content available in a growing media bed and the water channel, which is not desirable for blueberries.
Also, blueberries don’t need as much nitrogen as potassium. In fact, the high nitrogen content in aquaponics is unsuitable for blueberries. The finest blueberry harvest requires a growing media pH of between 4.0 and 5.5, which will destroy your aquaponics setup, especially the fish.
10. Grapes
Like berries, grapes are a nonstarter and thus among the worst plants you can use for aquaponics. Grapes don’t require highly acidic growing media, so they’re feasible in that sense in contrast to berries. However, grapes demand a lot of attention, care, and time.
You may not have any real grapes show up for three years or longer, depending on how you take care of the vine. While it may sound lovely to grow and have your grapes from an organic aquaponics farm, the reality is far more challenging than you may think right now.
Also, one of the reasons why many people try aquaponics is the minimal daily involvement and care. Many of the worst plants included in this guide, like grapes, demand consistent effort for general upkeep or care, not just the fertilization or supplementation and other essential interventions.
11. Fruit Trees
Fruit trees like apple, mango, and orange aren’t sustainable in aquaponics systems. First, these trees take a long time to mature and bear fruits. Second, the trees will outgrow your aquaponics system much before you have any fruit. Third, you need acidic growing media.
Even if you consider dwarf orange trees and think they’re manageable in a relatively small aquaponics system, the pH requirement of 5.5 up to 6.5 makes it a nonstarter effectively.
While oranges can tolerate an alkaline growing media of as much as 8.0 on the pH scale, you may not get the delicious fruits in that kind of setup. Orange trees are also vulnerable to salts.
All fruit trees will eventually need more space, and you must transplant them, usually outside your aquaponics farm. Regardless of the reasons and your personal preferences about fruit trees, most of your favorites are completely unsuitable for aquaponics systems.
12. Many Flowers
Several flowering plants are among the worst you can use for aquaponics. Like the fruiting and reproducing vegetables, flowering plants need all the macro and micronutrients to bloom. You may have a lot of leaves or shoots, but the flowers won’t blossom when they should naturally.
Consider chrysanthemums as an example. The stems, twigs, and leaves will grow in an aquaponics system. However, you may not have the buds, thus no flowers.
If you’re lucky to find a few buds, they may not bloom. All of these come down to macro and micronutrients.
Sometimes, the problem in the case of chrysanthemum is a deficiency of potash, phosphorus, calcium, or magnesium. In rare instances, overfeeding could be an issue, which is quite likely in aquaponics because of the abundant nitrogen or nitrates available in the growing media bed.
Aquaponics can facilitate a commercial system for one plant or multiple crops with similar growing needs. Alternatively, you can dedicate separate growing beds for the various plants. However, diverse plants with disparate needs will struggle within the same recirculatory system.
6 Plants Unsuitable for Rafts & Deep Water Culture Aquaponics
You can add and regulate fertilizers to growing media on a bed or dutch buckets, not if you have rafts or use deep water culture aquaponics. The water recirculated to the fish tank cannot have excess minerals. Otherwise, you will have algae bloom in the fish tank, among other surprises.
Rafts or deep water culture do not have growing media like in beds or dutch buckets. Thus, there is limited surface area hosting and retaining the bacteria necessary to convert the nitrites to nitrates. In effect, all nutrient-demanding plants will struggle in such aquaponics systems.
Furthermore, some plants, including vines, that are otherwise feasible in aquaponics need sufficient root growth and controlled fertilization, neither of which is readily possible with rafts or in deep water culture aquaponics.
Here are 6 plants that you may try to grow in other systems, albeit with steep challenges, but they are largely unsuitable for rafts and deep water culture aquaponics systems:
1. Tomatoes
Tomatoes are among the many nutrient hogs for aquaponics systems.
Firstly, you can’t grow tomatoes without adding nutrients to your aquaponics setup, especially phosphorus and potassium. So, you have to use fertilizers, preferably organic. That’s not viable, as the phosphates and other residual traces in the water will cause algae to bloom on your farm.
Also, tomatoes gorge on the nitrogen available in the water and growing media. Thus, you can’t grow them alongside other plants.
The nitrogen in an aquaponic system is derived from nitrites converted to nitrates, all of which depend on the quantity of ammonium released by the fish in the tank. In effect, other plants sharing the deep water culture setup will be deprived of nitrogen.
Furthermore, tomatoes don’t grow well on rafts because they lack the surface area necessary to host enough bacteria and worms for each plant to have bioavailable nutrients. It’s possible that you’ll notice very few or no fruits after months of labor and added costs with deep water culture.
2. Cucumbers
Like tomatoes, cucumbers are also nutrient hogs. However, cucumbers need less nitrogen and more phosphorus and potassium. Thus, growing cucumbers may not lead to nutrition deficiency in other plants sharing the aquaponic system, but you must provide potassium and phosphorus.
Adding phosphorus for cucumbers or tomatoes risks algae bloom due to the phosphates. Still, if you can manage that, you have to deal with the complications related to potassium. Adding a potassium supplement to aquaponics doesn’t guarantee adequate growth of cucumbers.
For one, both your fish and plants need potassium. So, the available potassium in the system must be sufficient for the cucumber plants and your fish stock. Plus, adding potassium won’t ensure its bioavailability for the cucumbers, as calcium and magnesium prevent its absorption.
3. Peppers
Both tomatoes and cucumbers are fruiting plants. Generally, reproducing plants aren’t ideal for rafts and deep water culture as they need a lot of nutrients, like fertilizers. Peppers are the same in this context. You need more than the trio of nitrogen, phosphorus, and potassium.
Peppers need calcium, magnesium, sulfur, iron, manganese, boron, zinc, copper, molybdenum, and other minerals. Also, peppers are vulnerable to both deficiency and excess or toxicity of many of these minerals. They’re difficult plants to grow and manage in aquaponics.
It is relatively easy to use fertilizers or a nutrient-rich solution in hydroponics, where your plants are the only component. An aquaponics system using rafts or deep culture is not suitable, as you cannot have heavily fertilized water flow back to the fish tank without any filtration and pH modification.
Rafts or deep water culture don’t have the kind of growing media on beds and dutch buckets retaining some of the nutrients for the plants that need a lot of nutrition.
4. Beans
Bush beans take up more horizontal space than you may have for each plant. This reason propels many aquaponic farmers and hobbyists to opt for pole beans. In fairness, pole beans are easier to manage, and the yield may be worthwhile given the occupied vertical space.
However, both bush and pole beans are vulnerable to excess nitrogen or nitrates in the growing media. Beans can use atmospheric nitrogen for their vegetative states. So, if your system has a lot of nitrates, the absorbed nitrogen will prolong the vegetative state of bush and pole beans.
A prolonged vegetative state means delayed flowering, and your beans may not develop the seed pods as you desire. Also, you need to ensure around 70% to 80% relative humidity for optimum growth and flowering, which is attainable in a greenhouse or the hot and humid tropics.
5. Squash
All popular squash varieties are nutrient hogs. Therefore, you have to use sufficient NPK (nitrogen, phosphorus, and potassium) supplements or fertilizers, depending on the variety you intend to grow.
Squash needs abundant nitrogen in the growing media even before planting. You cannot retain and build up nutrients with deep culture or rafts before planting unless you stop recirculating the water.
Another unsolvable issue is space. Pumpkins aside, zucchinis need a lot of space to grow. If you use dutch buckets, these containers must have a diameter of around 24 inches (~60.96 cm).
Allotting that kind of space on rafts or in any deep water culture aquaponics is a nonstarter. Also, zucchini is a sprawling plant, so it may take over a raft and another if one is nearby.
6. Peas
Like the other plants already discussed in this article, peas demand fertilizer or supplementation right from the outset. Additionally, peas create two significant challenges.
For one, excess nitrogen in deep water culture enhances foliage development but doesn’t lead to seeds or pods’ growth. Second, peas are vines, and they can easily overshadow other plants on the same raft or nearby.
In hydroponics, you can measure the electrical conductivity (EC) to measure the salts in a nutrient reservoir. Peas require a reasonably accurate assessment of the nitrates and the electrical conductivity in a system. However, there’s no way to do the latter in aquaponics.
Rafts or deep water culture aquaponics share a large and continuous growing media, basically water. Thus, it is practically impossible to manage the diverse nutrition requirements of plants demanding lots of minerals.
Tomatoes, cucumbers, peppers, beans, squash, and peas need dedicated beds with controlled fertilization, not easy or feasible with rafts or deep water culture aquaponics. Also, you must maintain the ecosystem, not only the circulating water’s pH but also the mineral constituents.
