HYDROPONIC GROWING 101


Growing Systems

Stationary Gutters

Living Lettuce / Herbs
Plants are seeded into trays. The seedlings are then manually transplanted into gutters. After the initial transplanting from seedling trays to the gutter the plants stay in the same gutter for the duration of the growing cycle. When ready to be harvested, the gutters are moved to the harvesting table for manual harvesting. In order to increase plant density, it is also possible to use different gutter sizes, starting off with gutters with several holes close to each other, optimal for when plants are small. As the plants grow, they need to be transplanted to a new gutter which allows for more space between the plants. Usually, this transplanting would be done at least three times. Each transplanting is done manually, and every time a plant is transplanted, the roots are shocked, and growth is slowed down for a few days.

Different gutter sizes means additional transplanting steps: Labor intense, but space efficient.
One gutter size means no further transplanting: Labor efficient, but not space efficient.


Floating Rafts

Living Lettuce
Plants are seeded into trays. After germination, seedlings are transplanted into boards or rafts and placed in a pond of water. As the plants grow, they need to be transplanted into a different board which gives the plant more space to grow. (fewer plants per board). The plants are typically transplanted 2-3 times. The boards are picked up out of the water, the plants transplanted to another raft and then placed back into the pool. Every time a plant is transplanted, the roots are shocked, and growth is slowed down for a few days. The boards are pushed to the harvesting end of the greenhouse, where they will be removed manually from the pool and transported to the harvesting station. Harvesting is done manually for living lettuce.

Baby Leaf Lettuce
Plants are seeded directly on the boards or rafts they will be growing in during the entire growing cycle. The boards are stacked in piles and moved from the seeder to a germination chamber by pallet truck. After germination, the pallets with the boards are brought to the growing area and placed into the pool in the greenhouse. The board is pushed from one end of the greenhouse to the other where it will be removed manually from the pool and harvested.  Harvesting can be done manually or automatically. Overall, the boards are typically handled manually by workers six times throughout one growing cycle. 


Moving Gutter System—Fully Automatic

Baby Leaf / Small Head Lettuce / Herbs / Microgreens
A fully automated growing process optimized for cut baby leaf lettuce, herbs and small head lettuce. The gutters are filled with the growing medium of choice followed by automatic seeding directly into the gutter. The gutter is then transported by conveyor belt and placed onto the growing line. While seedlings and plants are small, the gutters are packed tightly right next to each other, but as the plants grow the gutters are automatically separated to give the plants the space they need, but as little as possible. The gutters are moved slowly toward the harvesting station. When the plants are ready to be harvested, the gutters are transported by conveyor belt to the harvesting station, where the greens will be cut, mixed and packaged automatically.


Moving Gutter System—Automatic

Living Lettuce / Herbs
This is an automated growing system with a few manual steps optimized for head lettuce, living lettuce and herbs. Plant trays are automatically filled with pots and growing medium of choice followed by automatic seeding. The trays are then moved to the germination room. After germination the plant trays are placed on the nursery tables. When the seedlings are large enough, they are transplanted into gutters and placed on the growing line. The gutters move slowly toward the harvesting station, and as the plants grow, the distance between the gutters is automatically adjusted to give the plants just as much space as they need, but as little as possible. The plants are harvested manually. All steps in the growing process can be automated, except for the harvesting. 


Vertical Growing

Baby Leaf / Microgreens / Herbs
There is a range of different vertical growing options. The most common set up is growing the plants on trays which are then stacked in several levels. Another option is to grow the plants in channels which are placed vertically, creating a wall of channels. The vertical systems are still in the initial phase of development and have, to date, not been proven profitable in a commercial setting, mainly due to the high energy and labor cost associated with the operations. While space efficiency would appear to be an advantage, given the vertical aspect, the net growing area which needs to be cooled and lit is typically large and very inefficient as these shelf-type growing systems do not adjust the placing throughout the growing process. Providing consistent and favorable temperature conditions among multiple levels represents further challenges. 

 

 

Different Hydroponic Systems

 

 

   NFT: Nutrient Film Technique
 

NFT System

 

When using the hydroponic technology called NFT, Nutrient Film Technique, plants grow in long channels or gutters. A thin film of water circulates through the gutters to the roots of the plants. For successful growing the gutters need to be arranged with a slight slope to ensure the correct flow rate of the nutrient rich water. The main advantage of the NFT system over other forms of hydroponics is that the plants' roots are exposed to adequate supplies of water, oxygen and nutrients simultaneously.

The Green Automation systems use NFT as the chosen hydroponic system. The NFT, combined with Green Automation’s proprietary gutter and fertigation system, is a superior form of hydroponics. The system supplies the plants with water, oxygen and nutrients in the precise amounts required and constantly monitors the growing solution, ensuring the level required for efficient plant growth is maintained.


 

Ebb & Flow

ebb and flow

this is the simplest hydroponic method. The plants grow in individual pots placed in a pond. The pond is filled with nutrient rich water at certain intervals and then emptied. The roots of the plants do get sufficient nutrients, water and oxygen, but do not receive it simultaneously, which would be more beneficial for plant growth.

Deep Water Culture

deep water

The plants are placed in cassettes/trays in the nutrient solution pool. The roots are in constant contact with water.

Aeroponics

aeroponics

The plant roots hang suspended in the air in an enclosed tray/channel. The nutrient solution is sprayed onto the roots.

 

Choosing the Right System

The choice of growing system and the level of automation needed will depend on the planned plant variety and plant size. This overview will provide guidance and information concerning each system’s capabilities.

 

 

 

Automation and plant variety system comparison
Source: Green Automation