Selecting the best crops for raft systems (DWC)

laitue raft

You are starting an aquaponic operation. You’re not quite sure what crops to plant in your raft system (deep-water growing system), but you have some ideas.
To help you make these decisions, we have compiled a list of recommended crops for your raft system.
Before making your choice, remember that the choice of crop depends not only on the climate, technology and facilities, but also on the local market. If you don’t have a demand for your products, you won’t earn any money. That’s the end of it. Do a market research before you choose your crops!
Once the market research is done, you can consider other factors.
We have cultivated dozens of different types of cultures and we have had our share of failures. We have developed this guide to deep-sea cultivation (DWC) to help you learn from our mistakes and make the right crop choices from the start.

What is DWC?

For deepwater cultivation (DWC) or rafting systems, a tank with a nutrient solution (fertilized either with fish waste or hydroponic fertilizer) is used. A raft floats on the water and the plants on the raft hang their roots in the solution. The plants are supported on the raft by net pots or other tools such as Grow Grips.
This guide will show you the best plants for deep-sea cultivation. Each type of plant has a number of positive and negative qualities and offers unique possibilities for each growing situation. After reading this guide, you will have all the information you need to make the best choice for your deepwater crops, regardless of scale.

Factors in the choice of FDW crops:

Crop selection is a complex choice based on your individual crop situation. Instead of recommending cultures without context and clear methodology, consider the important criteria:
1) Weight
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Liferafts are generally quite durable and affordable, but they can only support a limited weight. The best crops for deepwater cultivation are small and light. Lettuce, for example, is a popular DWC crop and its ideal size for rafts. Without the root anchoring provided by a dense environment, plants growing high up can fall or break at the stems.
(2) Ownership (volume)
espacement culture raft
DWC systems operate on a single horizontal plane because they are generally too heavy to stack. This means that you have a volume/crop area ratio of 1:1. If you have limited space, consider a technique that can facilitate higher density. If you have a lot of space, the problem is not the same.
However, this means that you want to fill this horizontal plane efficiently. Make sure that the spacing between your plants on the rafts matches the size of your plants. (For example, do not leave 30 cm between each plant if you are growing romaine lettuce. You will waste a lot of space.)
3) Water-friendly
Plants and herbs that like dryness (such as rosemary) and prefer « dry feet » are not well suited for DWC systems. But thirsty plants like lettuce will thrive in deep-water cropping systems. Choose species and varieties that love water.
4) Yield (harvest potential)
If you grow for commercial sales, you want to make sure that the operation gives you a profit!
Make sure:

  • (a) to have a decent margin on the harvest
  • (b) to have a market to sell the crop. Don’t forget the opportunity costs in your analysis. (If culture A can provide you with a decent income, remember that there may be a culture B that can offer you more.)

5) Hybridity
Sustainability and vitality make hybrid varieties more viable in deepwater cultivation than traditional selectively grown varieties. Although heritage varieties are attractive, the best-known and most studied hybrids are a better value for your money.
With these criteria in mind, here are some recommended crops that can make your DWC installation a success.


Growth time: 8-10 weeks from seed
Basil is the most labour-intensive crop of our recommended DWC crops, basil is a unique plant. Stem trimming can change the direction of growth of the plant from mainly vertical to more bushy growth. This allows producers to get a better yield but it takes a little practice.
Although we do not recommend basil to new producers, consider choosing basil as a second or third crop rotation.


Growth time: 5-6 weeks from seed
Globetrotter lettuce is certainly one of the most popular crops in the world and is an excellent complement to any deepwater farm. Lettuce is one of the easiest plants to grow on any farm, and deep-sea cultivation is no different. With a short growth cycle and strong market demand, we encourage all entry-level producers in deepwater cultivation to consider lettuce as an option for their farm.
There are hundreds of varieties of lettuce; the preferred varieties are green or red Roman and mixed mesclun. Lettuce is an excellent first choice for new deepwater producers.


Growth time: 7-9 weeks from seed
The beautiful and delicious okra is common in African cuisine. Germination of okra requires soaking the seeds a few hours before planting.
Okra has beautiful flowers and is sometimes used as an ornamental plant in public gardens. Okra is an excellent crop.


Growth time: 5-6 weeks from seed
Kale is a great food. It is ideal for deepwater and indoor cultivation. Curly kale prefers cool temperatures and can be harvested in whole or in part by taking 30% of the plant at a time. Kale and lettuce are an excellent first crop.



Growth time: 4-6 weeks from seed
The cultivation of sorrel in deep water offers the possibility of growing this temperature-sensitive plant all year round.
Slightly acidic, sorrel is commonly used in dishes made with cream or sauce where the slight acidity of the plant can be managed by dissolution. Sorrel is not only an excellent complement to many dishes, but its beautiful flowering adds a beautiful touch to any cultivation operation.

Swiss chard

Growth time: 4-5 weeks from seed
Swiss chard is a leaf plant that we recommend. Swiss chard is more susceptible to powdery mildew than some other crops, so be careful with white powder and take proactive care of it.
With a little temperature control, Swiss chard will produce delicious leaves. Like kale, Swiss chard can be harvested in whole or in part. Swiss chard is a sustainable, tasty crop that is easy to grow in deep water.

Bok Choy

Growth time: 8-11 weeks from seed
A vegetable little known in Africa, bok choy (and its cousin Tatsoi) is a Chinese cabbage, an excellent choice for deep-sea cultivation. The different varieties of Bok choy have remarkable variations from one seed variety to another, so be sure to choose when you buy the seeds.
Bok choy is a little heavier than the rest of the crops in our recommended list for deepwater cultivation. Make sure your rafts are strong and ready to support the weight. Do not overload your rafts.


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