General Hydroponics

General Hydroponics

Crops
Crops produced in today’s modern greenhouse ranges are many and varied. They can be loosely
categorized as follows:

  • vegetables including tomatoes, cucumbers, fancy lettuces, bell peppers, cherry tomatoes and a host of minor ones such as radish, melon and strawberry
  • cut flowers e.g. roses, mums, carnations
  • potted flowers e.g. geraniums, azalea, poinsettia, tulip
  • numerous bedding plants

Growing Media
Porous, well aerated substrate are used as anchorage for the plants root system and feeding area. Rockwool and Heydite are the most popular as they are most readily available, and easiest to use and transport. There are various other mediums which are not as widely used.

Growing Techniques
There are different ways to bring water to the plants.

  • Nutrient Film Technique,
  • Drip-Irrigation or Micro-Irrigation,
  • Aeroponics / Deep Water Culture,
  • Flood & Drain,
  • Home Hobbyist Systems,
  • Passive Planters / Hydroculture.

Carbon Dioxide Enrichment
In an outdoor garden the CO2 level in the air is about 300 parts per million (ppm). Plants thrive when they are able to take in a higher level of CO2. Growers today monitor their greenhouse CO2 levels with special purpose control monitors which in turn operate CO2 burners or generators to replenish CO2 consumed by the plants.

HAF (Horizontal Air Flow)

Working with CO2 enrichment and indeed an important part of the greenhouse environment is horizontal air flow. Conceived in the late seventies following research involving finer aspects of greenhouse air circulation, horizontal air flow, or HAF as it is now referred to, is widely used.

Security
Commercial growers end up with very sizeable portions of their yearly turnover as work-in-process. The closer the crop gets to harvest, the higher the risk of catastrophic loss, should a key part of the greenhouse’s climate control system fail. Accordingly, growers go to great lengths to protect themselves. Early warning is a vital part of their security. Most now employ automatic phone dialers with electronic voice simulation to alert them of impending problems long before serious crop damage can occur.

Biologicals
Environmental concerns are uppermost in the minds of today’s consuming public. The horticultural industry has been working for many years to reduce its dependence on chemical pesticides, many of which have been linked to cancers. Numbers of key pesticides have been deregistered for particular crops, others have been removed from the market altogether. Promising advances have been made in the use of predator insects in greenhouse ranges as natural biological control against pest insects. While much work remains to be done to educate the grower in their use, progressive members of the industry are now well on their way to 100% biological insect control.

Bumble Bees
Until recently, pollination of greenhouse tomato crops was accomplished with a labourious method of fruit truss vibration utilizing battery operated hand-held vibrators (“electric bees”) manually touched against mature flower sets. It was a strictly artificial way of simulating natural pollination in the absence of a natural outdoor environment where wind and insects are the vectors. In today’s modern tomato ranges, hives of bumble bees are placed strategically amongst the crop and left to accomplish naturally what has been, until now a monotonous and tedious task for greenhouse staff.

Lighting
In order to get the best possible results from a Controlled Environment Agriculture System, we will need to bring the spectrum and intensity of sunlight indoors. This is accomplished using High Intensity Discharge lamps. These lamps, in conjunction with specially designed luminaries, will reflect light downwards to plants, where it may be utilized to the maximum.

Climate Controls
Modern greenhouses employ advanced environment control aids such as relays, humidistats, thermostats, CO2 injection systems and fans which are often controlled by a central computer. Smaller systems employ various individual control units.

Bioponics
The organic hydroponic display or Bioponics, we believe, is of significant interest to both commercial and hobby growers. This method employs an organic tea based nutrient solution with added microbial agents to facilitate their breakdown into mineral elements which plants are able to take in.

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