Period 4

Period 4


  • To start this period at the right time to achieve the target night time drop in water content.
  • The night time fall in water content is an important tool in control of the vegetative / generative balance of the crop and root health and development.

Start time

  • Period 4 will start at the end of Period 3 (4 to 5 hours before sunset).
  • This time is always difficult to judge as it is dependant on the amount of light received after the last irrigation round and the volume of substrate.
  • Guide water content drop figures overnight:
    • 0 to 5% - Vegetative
    • 5 to 10% - Generative
    • 10 to 15% - More generative
  • Figures of over 15% can be used with care but only at the end of the season when the slabs are full of roots as a method of maintaining root health.
  • See Season Dynamics.

Length of period

  • Until the start of Period 1 the following morning.

Dose size

  • It is best not to water during this period.
  • If very low volumes of substrate are used it may be necessary to put on one additional round during the late evening but only under extreme conditions.
  • If this is done a very small round is needed just to avoid too large a water content drop.

Time starts

  • None

Light starts

  • None

Other factors

  • Water content control is used widely in tomato crops especially at the beginning and the end of the crop to aid generative steering in the poor light levels.
  • In peppers it is being used more and more especially at the end of the year when moving into decreasing day lengths with a high fruit load to maintain root health.
  • With cucumbers the night drop is used less, but can be used when looking to promote flowering.