No products in the cart.
Hydroponic farming is an innovative and highly efficient way to grow crops without soil, using a nutrient-rich solution to nourish plants. While many crops thrive in hydroponic systems, others present significant challenges that make them difficult to grow. From cereals to parasitic plants, certain types of crops are simply not well-suited for hydroponics, either due to their growth habits, biological needs, or economic feasibility. In this post, we’ll explore the most difficult crops to grow hydroponically and the specific challenges they present.
Cereal crops like wheat, barley, rice, and oats are among the most challenging to grow hydroponically. Though they are annual plants, they have long life cycles and take a considerable amount of time to develop. These crops require many months of growth to fill their grains with starch and protein, which makes hydroponics less efficient. In contrast to faster-growing crops like leafy greens, cereals demand prolonged system operation, which raises energy and maintenance costs.
Another complication for cereal crops is that they require wind pollination. In many grow rooms the plants on the outside would not receive adequate delivery of pollen with the air circulation achieved to get the grains to develop fully.
An even more difficult cereal to grow hydroponically is maize (corn), including varieties like sweetcorn. Maize grows tall, often exceeding 3m, which means it takes up a lot of vertical space in a hydroponic system. This not only requires specialized equipment, but it also significantly increases the overall complexity of managing the growing environment.
So with their long growth periods and relatively low market value compared to quicker-growing crops, cereals are often not a practical choice for hydroponic systems.
Growing perennial crops and trees hydroponically presents unique long-term challenges. Unlike annual plants, perennials need to stay alive for extended periods, which can lead to issues like the degradation of growing media, build-up of disease, and accumulated nutrient imbalances over time.
In traditional soil-based farming, you can rotate crops and sterilize the soil between seasons. However, with perennials in a hydroponic system, you must maintain an environment that is continuously productive without the ability to “reset” the system. This means that issues such as algae growth, root rot, or nutrient imbalances tend to accumulate over time, requiring constant monitoring and intervention.
Fruit trees, which can grow quite large before bearing fruit, present an additional challenge. Growing media in hydroponic systems can degrade or become compacted, and managing the size of these plants within the constraints of a grow room requires careful planning and design. So, while it may be tempting to try and grow a plum orchard or bonsai trees hydroponically, the practicality of such an endeavor remains questionable unless there is a very compelling reason to do so.
Growing fruit crops hydroponically is an intricate and challenging task. To produce quality fruit, you need to manage several stages of growth, including healthy foliage development, flowering, pollination, fruit set, ripening, and post-harvest storage. Unlike leafy greens such as lettuce, which are relatively simple to grow with a focus on quick foliage production, fruit crops require careful attention to each stage of their life cycle.
Pollination alone can be a major challenge. While some fruit plants can self-pollinate, many require external pollinators such as bees or other insects. In a controlled indoor environment, achieving optimal pollination can be tricky without introducing live pollinators or using artificial methods. Moreover, the environment must be perfect for every step of fruit development, from bud formation to fruit maturation.
Despite these challenges, some high-value fruit crops, such as strawberries, are being grown hydroponically with success. However, scaling up to commercial production is still difficult, with very few farms able to achieve high-yield crops in a hydroponic setting.
Root vegetables, such as carrots, beets, and radishes, present significant challenges in hydroponic systems. These crops rely on a loose, malleable growing medium that allows their root systems to expand and grow as the plant develops. This is problematic in many hydroponic setups, which often use inert materials like mineral wool. Whilst full of air, mineral wool is composed of strong fibres that the developing vegetable will not be able to push through to create the swelling roots that are characteristic of these crops.
Additionally, root vegetables typically have a lower market value compared to faster-growing crops like leafy greens or herbs. From an economic standpoint, investing in a hydroponic system for root vegetables is often not cost-effective unless you are growing a particularly high-value crop, such as ginseng or wasabi.
A further complication arises in potatoes, where the tubers need to be kept in the dark for the whole of their life cycle. Otherwise they will turn green. The green pigment in potatoes is toxic to humans if ingested. Do not eat green potatoes! In hydroponics lots of the growing media used allows light to penetrate much further down than a conventional soil, so green potatoes are an issue when growing potatoes hydroponically. This is why most commercial hydroponic potato systems focus on the production of propagation tubers (known as ‘seed’ potatoes) rather than the harvestable crop.
Hydroponics involves a significant amount of water, which might suggest that aquatic plants would thrive in this environment. While submerged aquatic plants such as water lilies or duckweed could, in theory, benefit from hydroponic setups like Deep Water Culture (DWC), there’s a complication: microalgae.
Microalgae flourish in the same aquatic conditions, often outcompeting the aquatic plants you want to grow. Cleaning the algae off without harming the plants is a constant struggle, and controlling algae growth in such a water-rich system can be incredibly difficult without a sophisticated filtration and algae control system. Therefore, growing aquatic plants hydroponically is far from simple.
Carnivorous plants, such as Venus flytraps and pitcher plants, present a different set of challenges in hydroponics. These plants naturally thrive in nutrient-poor, acidic soils like peat moss, which is difficult to replicate in a hydroponic system.
While coco fiber is sometimes used as an alternative growing medium, it lacks the low-nutrient, acidic properties that carnivorous plants need to thrive. More problematic is their specialized feeding strategy—these plants obtain nutrients by trapping and digesting insects. Since hydroponics doesn’t offer the insects they require for nourishment, managing their nutrition and maintaining their unique growing conditions (such as low pH and low nutrient levels) becomes a complex balancing act.
As a result, growing carnivorous plants hydroponically often requires the creation of custom fertigation systems and pH control methods, making it a highly specialized endeavor.
Arid zone plants, including cacti and succulents, have evolved to survive in regions with little to no water. These plants are adapted to store water in their tissues and generally do not require constant moisture. Therefore, having their roots consistently submerged in water, as is the case in hydroponic systems, can lead to root rot and other issues.
The challenge with growing succulents or cacti hydroponically is that they are prone to rot if exposed to too much water, and they do not thrive in constantly wet conditions. Adjusting the water delivery system to meet the needs of these plants is difficult, and growing them in a hydroponic system is often not practical.
Calcicoles are plants that thrive in acidic environments, such as rhododendrons and azaleas, while calcifuges prefer more alkaline conditions, like lilacs or many orchids. To grow these plants hydroponically, you would need to either create a very specific nutrient solution for each type or adjust the pH of the solution dramatically.
Creating a nutrient mix for these plants is challenging, as it involves tailoring the water’s pH and mineral content to suit the specific needs of each plant group. As such, it can be highly difficult (and expensive) to grow these plants successfully in a hydroponic system.
Halophytes are plants that thrive in salty water, such as saltwort and seaside plants. Growing these plants hydroponically requires adding salt to the nutrient solution, which creates a host of problems. First, salt is toxic to most plants, so maintaining a system that only supports halophytes while preventing damage to other crops is tricky. Additionally, salt can build up in the system, clogging filters and nozzles.
The challenges become even greater when attempting to grow seaweed hydroponically. Seaweed’s complex life cycle, the risk of unwanted algae growth, and the high cost of production make hydroponic seaweed farming largely unfeasible.
Parasitic plants, like mistletoe and rafflesia, require a host plant to thrive. Growing these plants hydroponically would require optimizing conditions for both the parasite and the host, which can be a delicate balance. You would need to ensure that the parasite doesn’t completely kill its host and create a method for encouraging the parasitic relationship, such as replicating how seeds are transferred by birds.
Furthermore, since you’re working with two species in one system, you would have to deal with double the pests and diseases. Growing parasitic plants hydroponically is incredibly complicated and would require extensive knowledge and resources to get it right. However, if you were successful, you could become a horticultural celebrity for pioneering this highly unusual form of hydroponic farming.
While hydroponic farming offers incredible benefits, it is not a one-size-fits-all solution for all types of crops. Many plants—whether cereals, perennials, or parasitic species—present unique challenges that make them difficult or impractical to grow hydroponically. For most hydroponic growers, focusing on crops with high market value and relatively straightforward growth requirements, like leafy greens, herbs, and strawberries, is the best way to get started.
If you are looking for the simplest way to get epic harvests in a hydroponic system, then check out Eutrema’s revolutionary Liquid Gold. The only way to get from seed to crop with one bottle!
Article by Dr Russell Sharp, December 2024