In the gaps between urban skyscrapers and the desolation of Gobi deserts, groups of silver-gray containers are quietly nurturing green miracles. These redefined metal spaces are no longer mere carriers for cargo transportation but the crystallization of modern agricultural technology—plant factories. While traditional agriculture is constrained by land, climate, and seasons, container plant factories use modular design, intelligent environmental control, and soilless cultivation technologies to build a closed-loop agricultural production system that breaks free from natural limitations. Like a precision green manufacturing machine, it converts sunlight, water, and nutrients into measurable harvests, turning every inch of space into highly productive "farmland" and rewriting the relationship between humans and food.
Containers, as the physical carriers of plant factories, achieve efficient space utilization through standardized transformation. Their external dimensions are typically 1219224382896mm (e.g., Auma's cases), with internal polyurethane double-sided color steel insulation panels and tempered glass observation windows, ensuring both thermal insulation and visual management. The modular design allows flexible adjustment of planting units—for example, strawberry planting uses a 3-column, 4-layer, 3-tank structure, while leafy vegetable planting employs 2 groups of 13-layer vertical equipment, reflecting the feature of flexible adjustment. Nutrient solution tanks and circulation pipelines are integrated at the bottom of the container, with reserved installation positions for LED lights at the top, forming a closed and controllable production space. This design breaks through the geographical limitations of traditional farmland, enabling rapid deployment of micro-agricultural production units even in Gobi deserts or urban high-rise gaps, transforming "valuable urban space" into agricultural productivity.
Plant factories abandon traditional soil-based planting, with soilless cultivation as their core technology, establishing a cleaner and more efficient planting model. Common modes include:
Hydroponics: For leafy vegetable planting, a nutrient solution circulation system is used. In the Shanghai Jiao Tong University case, each layer is equipped with 3*36W plant supplementary lights, and nutrient solution circulation is automated via float valves and return pipes, yielding 27.5KG of vegetables in 21 days. In hydroponics, plant roots are directly immersed in nutrient solutions, avoiding the hidden risks of pests and diseases in soil, while nutrient absorption efficiency increases by over 30%. The growth cycle of leafy vegetables like spinach and lettuce is halved compared to traditional planting.
Substrate Cultivation: Strawberry planting uses drip-irrigation substrate cultivation, with white aluminum alloy frames supporting planting tanks and 2*28W special growth lights. A single container can grow 1,396 strawberry plants. Substrates like coconut coir and rock wool provide root support while precisely controlling water and nutrient supply via drip irrigation, reducing fruit deformity rates to below 5% and increasing sugar content by 2-3 degrees compared to open-field planting.
Aeroponics: Forage grass planting uses a top-spray system, activated 4-5 times daily, with a 6-day growth cycle yielding 7.5-8.5 times the seed weight. Atomized nutrient solutions directly contact roots, ensuring abundant oxygen supply and enhancing root respiration, which increases the crude protein content in forage grass by 15%, making it high-quality feed for urban animal husbandry.
Temperature Management: Air conditioners and heat pumps enable wide-range temperature control from -40°C to 120°C. In strawberry cases, wall-mounted air conditioners maintain a constant temperature to ensure uniform fruit ripening. In extremely cold regions, heat pumps convert external low-temperature heat into indoor temperature, reducing energy consumption by 40% compared to traditional electric heating. In hot summers, air conditioners and ventilation systems work together to lower room temperature from 35°C to 25°C within 30 minutes, avoiding high-temperature stress.
Humidity Management: Industrial humidifiers work with ventilation systems to control humidity in leafy vegetable planting areas at 50%-70%RH, with an error of ±3%. When humidity exceeds 80%, exhaust fans automatically activate for ventilation to reduce mold risks; when below 40%, humidifiers replenish water in pulse mode to maintain leaf transpiration balance.
Gas Management: Carbon dioxide cylinders or generators supply CO₂ as needed, maintaining concentrations between 400-2000ppm, while fresh air systems remove ethylene and other harmful gases. Studies show that increasing CO₂ concentration to 1200ppm boosts leafy vegetable photosynthesis by 50% and strawberry fruit set rate by 20%.
LED lights have become the mainstream choice, with a radiation utilization rate of 6.5% (far exceeding incandescent lamps' 0.2%), low heat generation, and adjustable spectra. For example, leafy vegetable planting emphasizes blue light (430-440nm) to promote photosynthesis, increasing leaf chlorophyll content by 20%; strawberry planting adds red light (610-780nm) to enhance sugar content, boosting fruit vitamin C levels by 18%. In Auma's cases, each layer is equipped with 36W supplementary lights, using intelligent controllers to set automatic on/off times and simulate natural light cycles—activating blue light in the morning to promote stomatal opening, switching to red-blue light combinations at noon to enhance photosynthesis, and gradually dimming light in the evening to guide plants into "dormancy mode."
The system consists of nutrient solution tanks, EC/PH sensors, circulation pumps, and filtration/disinfection units. Sensors monitor nutrient solution parameters in real time, and when EC values deviate from set ranges, solenoid valves automatically activate mixing tanks to adjust nutrient concentrations, managed via control software in a closed loop. For example, leafy vegetable nutrient solutions typically maintain an EC of 1.2-1.5mS/cm and a PH of 5.5-6.5. If PH exceeds 7.0, the system automatically injects dilute sulfuric acid for adjustment; if EC drops below 1.0mS/cm, it initiates concentrated nutrient supplementation. Ultraviolet and ozone dual-disinfection systems can kill 99.9% of harmful microorganisms within 30 minutes to ensure water quality safety.
Using hydroponic circulation systems, over 90% of water resources can be reused. Nutrient solutions are filtered through multi-layer devices to remove root exudates and suspended particles, then re-injected into planting tanks after ozone disinfection. For a container farm with an annual output of 10 tons of leafy vegetables, annual water consumption is only 300 tons—80% less than traditional open-field cultivation, equivalent to the annual water use of a 10-person household, embodying the concept of environmental protection and energy conservation.
Environmental Sensors: Monitor temperature/humidity (accuracy ±0.5°C/±3%RH), CO₂ concentration (accuracy ±50ppm), light intensity, etc., with real-time data uploaded to cloud platforms via gateways. In forage grass planting areas, when CO₂ concentration drops below 800ppm, the system automatically triggers alarms and activates gas supplementation devices; when light intensity is insufficient at 1000lux, supplementary lights automatically increase brightness.
Soil/Water Quality Sensors: Monitor substrate humidity, electrical conductivity (EC), PH, and NPK content. In forage grass planting, spray frequency adjusts substrate humidity to 60%-70% to ensure root health. Sensors collect data every 10 minutes, forming dynamic databases to support precision planting decisions.
Auma's data visualization system enables remote equipment monitoring, work order management, and traceability tracking. Users can view real-time data curves via mobile devices, set alarm thresholds (e.g., automatic alarms for temperatures >30°C), and generate production statistical reports. For example, managers can remotely monitor the growth curves of strawberries in a container and dynamically adjust light duration and nutrient solution formulas based on parameters like leaf area index and fruit expansion rate. The system also supports QR code traceability—consumers can scan vegetable packaging to view planting dates, environmental parameters, harvest personnel, and other information, ensuring full transparency from "farm to table."
In the Shanghai Jiao Tong University case, a single 40-foot container with 13-layer vertical planting racks holds 3,055 leafy vegetable plants, yielding 27.5KG of vegetables in a 21-day cycle, with an annual capacity 5-8 times that of traditional open-field cultivation. Through continuous multi-crop planting, the same container produces over 4,000 kg of leafy vegetables annually, equivalent to 1.5 mu of open-field vegetable gardens. Varieties like spinach and lettuce use blue light-enhanced illumination to shorten their growth cycle to less than 30 days, achieving high-frequency harvests of "one crop per month" to meet daily demand in urban fresh produce markets.
Strawberry planting uses substrate drip irrigation + red light supplementation, with 50-100 plants per square meter and a yield of 2.5-5KG/m². The enclosed environment effectively isolates pests and diseases like powdery mildew and thrips, reducing pesticide use to zero, with fruits meeting EU organic standards. Red light irradiation also promotes anthocyanin synthesis, giving strawberries a bright red color and extending shelf life by 3-5 days, making them popular in high-end fruit markets.
The aeroponic forage grass system has a 6-day growth cycle, with a seed germination rate exceeding 95% and a single harvest reaching 8 times the seed weight. Varieties like alfalfa and ryegrass provide high-fiber, low-oxalic-acid quality feed through precise light control (3000-3500lux) and spraying. A single forage grass planting container can produce over 20 tons of fresh grass annually, equivalent to 10 mu of grassland, and is not restricted by seasons, providing stable feed supplies for dairy farms and poultry farms around cities and reducing reliance on traditional forage planting.
Containers can be deployed on urban idle land, rooftops, or even basements, with a single container occupying about 30㎡. Vertical planting increases unit area yield by 5-10 times, solving land challenges in urban agriculture. For example, 10 containers arranged on a parking lot roof in a densely populated urban center can form an "aerial farm" with an annual capacity of 30 tons, meeting the leafy vegetable needs of 5,000 surrounding households and reducing energy consumption and losses from long-distance agricultural product transportation.
Soilless cultivation avoids soil degradation and heavy metal pollution, while circulation water systems reduce non-point source pollution, and enclosed environments eliminate pesticide drift. For example, 100 container farms can reduce fertilizer use by 20 tons and pesticide use by 500 kg annually, equivalent to protecting 500 mu of farmland ecology. Meanwhile, the low heat generation of LED lights reduces ventilation and cooling needs in traditional greenhouses, lowering carbon emissions by over 30% and supporting the "double carbon" goal.
Integrated Solar-Plant Factory Systems: Solar panels installed on container roofs enable "light-electricity-plant" cycles, as seen in Panasonic's cases where solar power accounts for 40% of supply. During the day, solar panels power lights and control systems; at night, stored electricity maintains operations, forming a self-sufficient energy system.
AI-Driven Intelligent Decision-Making: Introducing machine learning algorithms to automatically adjust environmental parameters based on crop growth stages, Dutch company Priva has achieved AI-driven dynamic light recipe management. By analyzing historical data, the system can predict the growth trends of different varieties in specific environments and issue early warnings 72 hours in advance for potential pest risks, reducing losses to below 5%.
Vertical Agricultural Ecosystems: Future plant factories may integrate with aquaculture and edible fungus cultivation to form composite systems like "aquaponics" and "mushroom-vegetable symbiosis." For example, treated fish farming wastewater can supply nutrients to vegetables, while oxygen produced by vegetable photosynthesis supports fish, achieving material recycling and improving resource utilization.
As a pioneer in plant factories, Japan has achieved large-scale production of lettuce and strawberries. Enterprises like Panasonic and Mitsubishi are promoting commercialization of container farms, with some projects achieving single-container annual revenues exceeding $100,000. The Netherlands leads in glass greenhouses combined with LED supplementary lighting, with companies like Priva and Signify dominating intelligent environmental control markets—their dynamic light recipe technologies can increase tomato yields by 40%. China has rapidly followed in recent years, with enterprises like Auma and Jixing building over 200 plant factories. Industrialization requires dual-driven policy support and technological innovation—governments can reduce initial costs through R&D subsidies and demonstration parks, while universities and enterprises can collaborate to establish talent training bases to address technical talent bottlenecks.
Plant factories, using containers as carriers and integrating soilless cultivation, intelligent control, and LED lighting as core technologies, have built an agricultural production system free from natural climate constraints. They are not only innovative solutions for urban food supply but also important milestones in agricultural modernization. In an era of increasing climate change and scarce arable land, this technology-ecology-integrated production model turns every inch of space into a fertile "farmland," delivering fresh and safe agricultural products across geographical boundaries to consumers' tables. With technological iteration and industrial upgrading, plant factories will eventually reshape how humans obtain food, making "harvests beyond traditional farmland" a sustainable reality and contributing Chinese wisdom to global food security and agricultural sustainability.
