+  pH Control (click here for more detailed information)
On a daily basis check and adjust the nutrient pH to within the range of 5.0 and an absolute maximum of 6.5.  However, note that although pH values approaching 6.5 are tolerable for very short periods, it is safest to maintain pH below 6.0.  When measuring pH, ensure to stir the nutrient thoroughly prior to taking the measurement - sampling error is one of the most common causes of failure to control pH.

+  Maintain nutrient conductivity at a constant level (click here for more detailed information)
Using a ‘conductivity’ or ‘TDS’ meter, check the nutrient strength every few days and if necessary add nutrient to maintain the initial target concentration.

+  Dump and Flush Regularly (click here for more detailed information)
To avoid the build up of toxic salts dump the nutrient preferably every 7th day then thoroughly flush the root system with fresh water before re dosing.  This is particularly necessary when using salty make-up water because nuisance chemicals build up more rapidly to toxic levels making it necessary to dump more frequently.

+  Regularly sterilize the nutrient solution (click here for more detailed information)
The nutrient solution is where most root diseases breed and therefore must be routinely sterilized.

+  Pre sterilize raw water
Untreated surface waters such as dam, creek, lake, etc., must be sterilised 24 hours prior to use. New RO and scheme waters are normally sterile. Also, because the quality of all waters deteriorate during storage, they should be regularly treated. Further, always store such waters in the dark.

+  General hygiene of the growing area (click here for more detailed information)
To achieve maximum growth and minimum problems from pests and diseases, absolute cleanliness of the growing area is a must.  Diseased foliage and general debris should be promptly removed from the growing area.  Additionally, surfaces should be kept clean from dust, dirt and spillages.

+  Lighting intensity, duration and wavelength  (click here for more detailed information)
When growing indoors, avoid using excessive light otherwise photorespiration can occur. 

+  System design (click here for more detailed information)

-  Ensure the system design allows fresh nutrient (i.e. optimum pH, conductivity and oxygen content) to be delivered to the entire root-zone with each watering.   Root growth must not be restricted.

-  System design should enable aeration of the nutrient.  This is best achieved using an air-stone and pump.

-  Avoid overcrowding of plants otherwise humidity, carbon dioxide / oxygen and light levels will be restricted.

-  Ensure there is sufficient air circulation around the foliage.

-  For recirculating systems, assign at least 10 litres of nutrient to each large plant.  Doing this will help minimize pH and conductivity fluctuation.

+  Medium type  (click here for more detailed information)
The medium should have excellent drainage qualities and enable high oxygen levels.  Also, the use of inert mediums is preferred because these permit regular sterilization of the nutrient and root region.  The required ‘water’ retention properties in a medium will depend upon climatic conditions and the rate of watering.  Avoid over-watering if the medium is prone to water-logging.

+  Humidity control (click here for more detailed information)
Maintaining relative humidity (RH) at around 60-70% is essential.  This helps govern the rate of “transpiration” which is responsible for the distribution of nutrients throughout the plant.  Optimum humidity also prevents spore germination for many types of disease.

+  Temperature of air  (click here for more detailed information)
Optimum daylight air temperature is around 25^oC.  The air temperature must be allowed to drop by at least 5^oC at night i.e. to 20^oC.  If growing cuttings, the use of bottom heat is highly beneficial.

+  Pruning (click here for more detailed information)
Prune old, overcrowded or damaged growth.

+  Appropriate nutrient formulation (click here for more detailed information)
Always use ‘grow’ and ‘bloom’ nutrient formulations at appropriate times.  Doing so will help ensure that your plants do not prematurely run out of nitrogen during the vegetative phase or potassium during flowering (especially for heavy fruiting plants such as tomatoes and strawberries).

+  Insects (click here for more detailed information)
They feed off plants and therefore spread disease from one plant to another via sap transfer. Use “yellow sticky traps” to give forewarning that insects are present.

+  Nursery stock  (click here for more detailed information)
Ensure seeds and media are from a reliable source and sterile. Since an incubation period is required for spores to germinate and become recognizable, looks can be deceiving. Also, diseases can lay dormant for long periods of time until exposed to the correct conditions.