Not from the roots, Water temperature is controlled to increase oxygen absorption and intake. What I believe you are talking about occurs from the relationship of the roomâ??s temperature to the leaves and stems. You need a very cool climate during the light period and controlled temperature during the dark period too. Keep the swing over 24 hours (light & dark) with in 72-78f for the whole growth of the plant. The leaves will be smaller and the bud area will be larger and denser if you do.