Hydroponic Vegetable Growth: A Graphical Primer


The Graphical Primer allows the users to explore the optimal values of solution pH, electrical conductivity, air and root temperature, and relative humidity depending on the growth stage of the plant and certain climatic conditions. The links below allow you to explore the growing conditions that lend themselves to having a successful crop. It is important to note here that a “successful crop” is defined here as a high yield high quality crop which implies, conversely, that an unsuccessful crop could be, not only, low yield, low quality but perhaps low yield, high quality.

To explore this primer, you must choose the growth stage of the plant you want to learn about. The growth stage largely determines the optimal values of the growing conditions. Following that you can explore each of the five growing parameters listed above. There will be more than five choices because other climatic conditions affect the optimal ranges. For instance there are different optimal ranges for electrical conductivity depending on whether it is sunny or cloudy.

Growth Stages

There are five growth stages considered here and they are defined as follows, by (CropKing, Inc. 1993). You will be able to select which of these represents your tomato plant(s) the best.

  1. Germination and early growth stage: starts from the time of sowing the seeds until the seed’s coat breaks and the roots emerge.
  2. Seedling Stage: starts from the time the seed’s coat breaks and the roots emerge until they are transplanted into growing media.
  3. Vegetative stage: starts from the time the seeds are transplanted into the growing media until the first flower opens.
  4. Early fruiting stage: starts from the time the first flower opens until the first fruit is picked.
  5. Mature Fruiting stage: starts from the time the first fruit is picked until the termination of the crop.

Other Climatic Factors

Other climatic factors affect optimal growing parameter values. These are, whether it is night or day and whether it is cloudy or sunny.

How To Use The Program

ph GraphHere is an example of the graph which shows pH. The term “Growth Response” on the y-axis refers to a preference. It is the preference level that a typical expert grower would want for a value of the parameter so that a crop will be successful – high yield, high quality. The x-axis is the growing parameter, in this case pH. This is a measure of the acidity of the feeding solution.

Here it is apparent that the optimal range for acidity is between a pH of 5.5 and 6.5. It turns out, in this case, that this optimal range is true for all growth stages.