After the cannabis cuttings or clones have developed a substantial root base, the plants need to grow: the vegetative phase. The “Veg” rooms are conditioned to ensure the plants grow to their optimum size without flowering.
Light Schedule & Intensity
Light intensity in these rooms is low to moderate. The light schedule in this room begins with lights on for eighteen hours, and off for the remaining six. This simulates spring and early summer and inhibits flowering. But generally, these are larger rooms and so there is often more total heat and humidity in the veg room compared to the previous two stages.
Temperature & Humidity
That means larger HVAC units are required to deal with the load. Desired temperature ranges are still 75°F to 82°F (23°C–28°C) with 60% to 70% RH.
Vapor Pressure Deficit
Similar to the mother room, the higher VPD helps stimulate growth through increased water intake.