Keeping Things Comfortable

With the plants developing, Sarah and Jasmine now have to tackle one of the trickier parts of the grow: keeping temperature and humidity under control.

This episode sees them set up heaters, humidifiers and dehumidifiers before Ian explains why getting the balance right is so important throughout the grow.

What You’ll Learn

This episode covers one of the most important parts of any grow environment:

What VPD means and why it matters
How to manage temperature and humidity throughout the grow
How heat and humidity requirements change at different stages
How to set up and position heat and humidity equipment

Understanding VPD

What Is VPD?

VPD stands for Vapour Pressure Deficit. Ian explains that it describes the relationship between temperature and humidity in the growing environment and changes depending on the stage of the grow.

Following the VPD curve becomes particularly important when using LED lighting, helping growers maintain the conditions plants need as they develop. More information on VPD is available here.

Why Humidity Matters

Plants return a large proportion of the water they receive back into the air, so controlling humidity is an important part of maintaining the growing environment.

Too much humidity can create conditions where bacteria and mould become a problem, while HPS lighting can remove humidity from the environment, making humidification necessary.

Common Heat & Humidity Mistakes

Ignoring Humidity

Humidity can change significantly as plants develop, so it needs to be monitored and adjusted rather than left to chance.

Poor Equipment Positioning

Positioning humidifiers, heaters and dehumidifiers correctly helps distribute their effect throughout the growing environment.

Letting Humidity Get Too High

Excess humidity can create conditions where bacteria and mould become a problem, particularly during stages where humidity should be lower.

Forgetting To Check Your Equipment

Humidifiers need topping up and dehumidifier tanks need emptying regularly. Keeping on top of the equipment helps maintain consistent conditions.

Temperature & Humidity Through The Grow

Propagation

78% humidity · 28°C.

These are the conditions Ian recommends for cuttings. With humidity this high, keeping the environment clean is particularly important to avoid mould.

Early Veg

65% humidity · 26°C

As the plants move into early veg, humidity can be reduced while maintaining a temperature of around 26°C.

Flower

45–50% humidity · 26°C

Humidity is reduced further as the plants move into flower, with temperatures remaining around 26°C.

Late Flower

45% humidity

Humidity is reduced further again during late flower.

Featured Products

Sonic Air Pro Humidifier

Ora Dehumidifier

Sonic Air 23L

Sonic Air 10L

IHC Controller

Day & Night Controllers

The Environment Is Taking Shape

The right temperature and humidity can make a huge difference as the plants move through each stage of the grow. With Sarah taking another point and the environment now under control, the growers are ready to tackle the next part of their setup.

The Scoreboard

The pressure was on this week as both growers tackled the heat and humidity setup. Sarah got her equipment set up quickly and with relatively few issues, while Jasmine struggled and needed a helping hand from the others. That gives Sarah the point this week.