Hydroponic production offers an alternative for small-scale vegetable growers who without access to arable land or sufficient space. While upfront costs tend to be high, hydroponic farming can be a lucrative venture if approached and implemented carefully.
With many hydroponic systems available, farmers should rely on expert advice before choosing one.
Photo: Pexels
Hydroponics, a system of growing plants in nutrient-rich water rather than soil, is suited to producing a wide variety of vegetables. In South Africa, tomatoes, cucumbers, peppers, and leafy greens are among the most common hydroponic crops.
One of the key advantages of hydroponic production is efficient water use compared with conventional farming methods. In some closed-loop systems, where the nutrient solution is recirculated, it is estimated that usage can be reduced by up to 50%.
Even in open systems, where excess water is drained away, farmers can potentially save between 20% and 30% compared with field irrigation methods.
In the temperature-, humidity-, and light-controlled environments of greenhouses and tunnels, plants receive a constant supply of essential macro- and micronutrients, enabling faster, more vigorous growth and higher yields.
Recirculating systems operate in a closed loop, feeding plants with a nutrient solution pumped through channels.
They can also be planted at higher densities, as their root systems remain smaller. Additionally, soil-borne diseases are eliminated, and clean, contamination-free, high-quality produce is ensured. Production can also take place year-round.
While hydroponics offers impressive production efficiencies, it is a technically demanding approach that requires consistent management and an understanding of system dynamics. In the absence of soil, plants can absorb water and nutrients more efficiently, but this also means they are more vulnerable to any disruptions in the system.
In its guide to hydroponic vegetable production, the Agricultural Research Council (ARC) has the following advice for small-scale farmers considering hydroponic production: “To be able to produce vegetables successfully year after year, you need to be familiar with the basics of hydroponics: the plant, growth medium, water, and nutrients. By relying on recipes only, you will not be able to identify the cause of a problem, and you may not be able to correct it.”
Determining climate suitability and understanding the market for a chosen crop are also critical starting points. Therefore, venturing into hydroponics for the first time or diversifying should be carefully considered with ARC cautioning that these enterprises typically involve substantial upfront investment, are labour-intensive, and demand daily oversight.
Choosing the right crop is fundamental to success in hydroponics. Both seeds and seedlings can be used, with certain varieties specifically bred for greenhouse environments. Farmers are encouraged to consult their local seed companies for recommendations on well-adapted, easy-to-grow cultivars.
When sourcing seedlings, the ARC emphasises the importance of selecting young, healthy plants with vigorous white roots, while avoiding those that are brown or pot-bound. Only the strongest seedlings should be selected for transplanting.
In hydroponic systems, specially formulated liquid fertilisers are used. These fertilisers are of higher purity – and therefore more expensive – to prevent blockages that can be caused by nutrient precipitation in pumps and pipes.
In terms of hydroponic systems, some perform better in warm conditions, while others are more suitable for cooler environments, making it essential for farmers to choose one suited to their local climates. Those in colder regions will also need to take additional steps to protect crops.
There are two main groupings of hydroponic systems: recirculating, and open bag/drain-to-waste. The nutrient film technique (NFT) is an example of a recirculating system ideal for growing herbs, lettuce and other leafy greens, and strawberries. Plants are inserted into PVC channels supported on specially designed tables, and a reservoir feeds the system. (Small operations can opt for barrels, but larger ones will require tanks.)
In greenhouse environments, crops are cultivated under optimal temperature, humidity, and light conditions.
Operating in a closed loop, the system continuously circulates a thin film of nutrient solution through the channels, allowing it to reach the plants’ roots. This method supports high planting density and allows for faster crop turnover, helping farmers maximise yields from limited space while significantly reducing their water inputs.
However, initial setup costs and the need for specialised equipment must be taken into account when considering this system.
Open bag systems are used extensively throughout Africa and are ideal for crops that require trellising or grow up to 1m high. Tomatoes, brinjals, and peppers are often grown in this system. A single plant is planted per bag in a growth medium such as sawdust, wood shavings, or sand – or a combination of these – and each receives its own nutrient solution through drip irrigation.
The advantages of this system are that it is relatively cost-effective to install and manage, and the bags are also inexpensive. The disadvantages are higher maintenance costs and a nutrient solution that isn’t recirculated.
Marco Rugani of Toscana Herbs and Fresh Produce in Muldersdrift, Gauteng, has been growing celery hydroponically for several years. This venture was a gradual addition to his existing operations and one that was carefully considered.
Having already cultivated celery successfully and established a reliable customer base, Rugani decided to diversify into hydroponics with the same crop. Funds from the existing business were channelled into setting up the hydroponic system, which, after some time, began to pay for itself. Most of the produce is sold to the Shoprite Group, and the intention is to maintain it as a small-scale operation.
Rugani acknowledges that choosing a hydroponic system can be daunting for beginners, with many options available, including misting, floating, and drip systems.
“So, you have to do research, consult with experts, and simply experiment to find out what works best,” he advises.
He uses the NFT system for his celery production and is quick to point out that purchasing a system is only the beginning, since setting it up correctly is crucial. “We had to get someone to set ours up and make the channels for us,” he explains.
For farmers without a greenhouse, Rugani suggests using a shade cloth system as an alternative, but also warns against cutting corners: “If growers are going to go into hydroponics, they should invest in it properly.”
He highlights crop selection and researching the market to determine demand and a customer base as other critical factors to keep in mind.
“Farmers must choose a high-value crop because this is a high-investment operation. Strawberries and cucumbers do well, but there’s a limit to the market and the seasons. If you’re producing in July, when it’s more expensive due to heating costs, you can’t expect to get July prices in December.
“If you choose to grow spinach – because after-Christmas supply is always short – remember that for the rest of the year, there’ll be eight months where it’s oversupplied. So, you’ve got to find your niche.
“Since I’d been supplying the same market for a long time, I was confident that if I had a good celery crop, I would be able to sell it. But even on our small piece of land, we sometimes throw away a house or two because it’s oversupplied.
“The bottom line is this: if a crop works and you find a market that wants to buy it, you can replant it over and over, and then you’ll make money. But if you grow a beautiful crop and put it on a flooded market, you’re going to struggle,” Rugani advises.
He also emphasises the importance of understanding climatic conditions. He points out that while growing undercover in a suboptimal environment is possible, “you’ll be competing with other farmers in better climates”.
Hydroponics is an enterprise that demands time, effort, dedication, and a clear understanding of crop production and the market, says Rugani.
For small-scale farmers with capital to invest, his advice is to diversify with what already works. “Start small, use your current experience, and build from there. But you still have to get many elements right, like your marketing, so know that it’s a process.”
For hydroponic system design and installation, hydroponic kits, and more visit futurefarmssa.co.za. For small-scale growing tunnels, visit horticulture.dicla.com. To buy hydroponics systems and accessories, visit urbanorganics.co.za.
FAST FACTS
- Vegetables that can be successfully grown hydroponically include tomatoes, brinjals, peppers, and leafy greens.
- Compared with traditional irrigation, hydroponic systems, especially closed-loop setups, use considerably less water.
- Hydroponics enables year-round vegetable production, but selecting a system suited to a region’s climate is essential.
Sources
https://www.arc.agric.za/arc-vopi/Pages/Crop%20Science/Hydroponic-Vegetable-Production.aspx#:~:text=Hydroponics%20is%20becoming%20a%20very,capital%2C%20labour%20and%20management%20intensive. (production)
https://www.agribook.co.za/hydroponics-undercover-growing/ (production)
https://drygair.com/blog/climate-water-hydroponic-agriculture-series-part-3/ (water)
https://puregreensaz.com/blog/nutrient-film-technique/ (system type)
https://www.commercial-hydroponic-farming.com/open-hydroponic-systems/ (system type)
https://hydroponicway.com/hydroponics-in-climates/ (why climate of an area is important)
