Grow Room - What to Measure and When

Temperature and Humidity

Temperature is measured in either Fahrenheit or Centigrade and the humidity relates to the amount of water vapour in the air and is measured as a percentage. A decent thermo-hygrometer will allow you to switch between the two temperature readings styles.

Measuring these is a constant requirement through all of the growing stages. Give a new grow room a couple of weeks to settle and once up and running keep a continuous eye on both variables.

An 'operational window' is the lowest and highest values that your environment can reach. Temperature can affect the humidity, and an example is on a summer's day you can increase the humidity which will also lower the temperature. It's important not to overdo this as it can result in bacterial growth. In the winter you might use a heater but it can also dry the environment. Finding a balance is the key.

The temperature at the plant canopy is of most importance.

EC & pH

EC is the Electrical Conductivity which is effectively a measurement of the dissolved nutrients in the solution. The pH of a solution indicates how acidic or alkaline it is. It ranges from 1-14, with 1 being the most acidic, 14 is the most alkaline and 7 is neutral, in the same way as pure water is. The EC is often measured in parts per million (ppm) or milligrams per litre (mg/L).

As a good starting point, measure the pH and EC of the water being used, straight from the source.

Get your nutrient solution prepared in a container then use pH Up or pH Down to get the pH at the best level, between 5.5 and 6.5, before feeding it to the plants. Don't mix them and use them sparingly!

If dramatic shifts in either the EC or pH levels are observed it could point to either ill plants or a problem in the setup so if a problem is discovered then measuring these should be one of the first solutions to aim for. Bear in mind they can both be affected by the ambient temperature.

Airflow

Airflow is a subject in itself but as a brief overview it is worth remembering that, as with most equipment, filters and fans will wear out as time progresses. Also, check it is fully functional when first bought! To check the speed of the airflow a device known as an Anemometer is useful.

Light Levels

Just as standard household lightbulbs need changing from time to time the hydroponics lighting does not last forever. Lighting is measured in lumens, candles, lux and many more units and a decent light meter will give an indication of how effectively it is performing.

When new lighting is set up give them an hour to fully kick in then take a measurement. Continue to measure it on a monthly basis, with the most important place being at the plant canopy.

Your Plants

It's probably fair to say that the most important thing in your grow room is the plants themselves! To avoid introducing anything unwanted be sure to wear protective clothing and wash your hands on a regular basis.

Bending, shaping and pruning your plants needs to be done frequently and measure the weight, colour, length and girth of them too. Environmental factors will influence these. Let your plants do their thing but always keep a watchful eye out for them!