Cold Stress

Whole-plant reddening or purple tones combined with slow growth, often overnight. Many plants produce anthocyanins as a stress response to cold. Nutrient uptake is reduced below 18 C.

What usually causes it

• Night temperatures below 16-18 C
• Cold fresh-air intake hitting the canopy directly
• Cold water being applied to root zone

Related product categories

• Climate & Ventilation

Terms worth knowing

• VPD (Vapour Pressure Deficit)

Walk the questions if you are not sure this is the match. The notes above are the same ones the tool ends on.