Have you ever seen factory-grown daikon radishes or carrots? You hardly ever see them in supermarkets, right?
Leafy greens like lettuce are completely established as factory vegetables, and you see them often.
Leafy vegetables are the mainstream in plant factories. In fact, they’re almost exclusively leafy vegetables. On the other hand, no plant factories are producing root vegetables.
“Wouldn’t it be nice if they grew more kinds of vegetables?”
Don’t you think so?
There’s a reason for that, but the types of vegetables that can be grown in plant factories are quite limited in the first place.
Root vegetables are a difficult category to grow in plant factories. That’s because the characteristics of root vegetables don’t mesh well with hydroponics equipment in plant factories.
So, in this article, I’ll explain the reasons why it’s difficult to grow root vegetables hydroponically.
If you’re wondering, “Why are plant factories only growing leafy vegetables in the first place?” please refer to the following article.
Challenges of Growing Root Vegetables in Plant Factories
Root vegetables are a general term for vegetables such as carrots, daikon radishes, and burdock root, whose roots are enlarged and grown for consumption.
Root vegetables are characterized by their taproot nature, forming a thick root that grows straight down deep into the ground.
To support the growth of this root, a soft medium with sufficient depth and width is required.
In simple terms, you can’t grow them unless there’s enough space for the roots to grow and enough strength to support them.
However, the mainstream equipment in existing plant factories is mostly optimized for leafy vegetables. It’s difficult to secure the depth and width necessary for growing root vegetables.
In addition, it is also a challenge that oxygen supply to the roots tends to be insufficient when the root zone is filled with liquid.
Cultivation Techniques for Plant Factories Suitable for Root Vegetables
Well, to be blunt, root vegetables should be grown in soil.
I don’t think you need to force yourself to grow them in a plant factory.
If you absolutely have to grow root vegetables in a plant factory, two techniques are possible: Nutrient solution soil culture and aeroponics. These are facilities of a type where the Nutrient solution does not circulate, which is different from the image of “plant factories.”
What is Nutrient solution soil culture?
A method of putting soil with sufficient depth for root growth into containers such as planters and supplying Nutrient solution with drip tubes. Because roots can be grown straight in the soil, it is ideal for the natural growth of root vegetables.
What is aeroponics?
A type of hydroponics in which Nutrient solution mist is sprayed directly onto the roots. The mist particle size is as small as several tens of μm, so it is characterized by being able to supply sufficient oxygen to the roots along with water and nutrients, and is a technology that can be a new option for root vegetable cultivation.
With these methods, you can secure the medium space and oxygen supply necessary for root vegetables, and also sufficiently supply the nutrients necessary for hypertrophy with Nutrient solution management.
The Problem That It’s Not Profitable in the First Place
I think this is the biggest problem.
Growing root vegetables in plant factories is technically possible, but it’s not profitable at all.
Root vegetables are characterized by a longer growing period and lower turnover rate compared to leafy vegetables. In plant factories, the amount of production per unit period, that is, the turnover rate, is directly linked to profits.
Root vegetables are at a disadvantage in this respect compared to other crops. That’s why they aren’t chosen.
While leafy vegetables such as lettuce can be harvested in about 30 to 40 days, carrots take about 70 to 120 days from sowing to harvesting, and the difference is clear.
In plant factory businesses started as a business,
Okay! Let’s grow daikon radishes even though we won’t make a profit!
That kind of mysterious development will never happen.
Plant factories are realistically limited in the types of vegetables that can be grown due to cultivation technology and economic aspects. For example, other things like grains are also quite difficult.
I’ve written about this in the following article, so please refer to it if you like.
The Future of Root Vegetable Cultivation in Plant Factories
For the time being, root vegetables will not be chosen with conventional hydroponic equipment.
However, that doesn’t mean that things will never change.
In the first place, root vegetables are not chosen because the equipment is not specialized for root vegetables. If cultivation equipment specialized for the growth characteristics of root vegetables is developed, there are endless possibilities.
In the future, cultivation equipment specialized for root vegetables will be developed, and a sales strategy for high-value-added root vegetable products will be established. Root vegetable plant factory cultivation may become a reality.
However, even in that case, considering the competition with other high-priced crops, the possibility that root vegetables will be chosen may not be very high.
For root vegetable plant factory cultivation to become full-scale, many technical and management hurdles will need to be overcome.
Root vegetable cultivation in plant factories is currently characterized by a large gap between the growth characteristics of root vegetables and the current plant factory equipment and business model.
Conventional hydroponic equipment is not suitable for root vegetables that grow straight and become hypertrophic, and it is necessary to introduce new cultivation technologies such as Nutrient solution soil cultivation and aeroponics.
Root vegetable cultivation in plant factories still faces many technical and management challenges.
For the time being, it may be realistic for plant factories to focus on the stable supply of leafy vegetables, and for open-field cultivation and greenhouse cultivation to be responsible for root vegetables.
However, if innovative cultivation technology specialized for root vegetables is developed in the future, and a sales strategy for high-value-added root vegetable products is established, the situation may not be zero.
What are the advantages of growing vegetables in plant factories?
The advantages of growing vegetables in plant factories include year-round stable production, stable quality, pesticide-free cultivation, labor saving and automation. They are particularly suitable for growing leafy vegetables.
What are the types of plant factories?
There are two types of plant factories: solar-powered and fully artificial light. Solar-powered factories use sunlight as the primary light source and supplement it with artificial light as needed. Fully artificial light factories use only artificial light without sunlight. In addition, there are plant factories specifically for seedling cultivation.
What vegetables are grown in plant factories?
Currently, the main crops grown in plant factories are leafy vegetables. Lettuce, salad greens, baby leaf, spinach, and komatsuna are typical examples. Tomatoes and strawberries are also grown in fruit vegetables. On the other hand, root vegetables such as carrots are currently considered difficult to grow in plant factories.
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