Heat; the number one enemy to the indoor garden. Even on a temporary basis, heat can cause many problems for our plants that result in a less than ideal product at harvest. When air temperatures exceed 78 degrees Fahrenheit bud structure starts to "stretch" in an attempt to increase the plant's ability to cool itself with airflow. This departs from the gardener's goal of growing dense and compact buds.

In addition, air temperatures will also heat the reservoir, planting medium and worst of all it will heat your root ball, making it far more susceptible to water born pathogens. Furthermore, water's ability to retain dissolved oxygen is greatly reduced as it heats up. This is largely due to the increasing rate of dissipation as water heats up.

So we now know that heat is a bad thing; how do we beat it?

Traditionally we used to beat the heat with ventilation and/or air conditioning, however there is another way to help you plants deal with heat fluctuations.

For this solution we look towards nature. Time and time again folks come into our stores with heat issues in their indoor gardens. When I begin explaining the effects of heat on their plants they immediately start telling me that their outdoor plants survive 95+ degree days routinely with no ill effects.

Absolutely true; outdoor plant's roots extend well over 3 feet below the soil's upper humus layer. Down here the roots have access to cold water, usually around 55 degrees. On a hot day, plants increase their transpiration rate in order to pump more of that cool water up and through their capillary system helping the plant to "thermo-regulate" during these hot days.

Learning from this concept we realized the importance of continuous irrigation systems that can be cooled by a chiller providing indoor plants the same ability as their outdoor counterparts.

This is not to say that you can run your room with constant air temperatures of 110 degrees and cool your water temps to 60 degrees while expecting your plants to be impervious to those kinds of continuous excessive air temperatures. Chilling your root ball only gives your plants significantly more "wiggle" room as far as temporary temperature fluctuations are concerned.

For example, should the compressor in your air conditioner overheat and shutdown for a few hours, plants with a chilled root ball will weather a bad situation like that without any issues.

Chilling the root ball keeps your root system healthy and free from pathogenic infection. This helps your plants survive more extreme conditions should your indoor garden suffer some sort of equipment failure that results in excessively warm air temperatures.

High tech grow rooms with CO2 enrichment systems require the air temps to be slightly warmer to help the plants absorb more CO2 by increasing the transpiration rate. However, we still need to keep the roots from overheating so the plant can efficiently benefit from the increased CO2 levels.

Remember, grow rooms are always limited by their weakest link. You can setup a grow room with the best lights and most cutting edge hydroponics system, but if you ignore the climate control it will limit the potential of your eventual harvest.

The following list outlines the basic aspects that influence the growth patterns of your indoor plants:

1. Air Temperatures

2. Light intensity (lumens, PAR, spectrum)

3. Water/Nutrient solution pH level

4. Base Nutrient Availability; NPK

5. Parasitic, fungal or harmful insect presence (e.g. spider mites, powdery mildew, etc.)

6. Dissolved oxygen levels in the water/nutrient solution

7. Water/medium/root ball temperature

8. Air levels or accessible air within the root ball

9. Room atmospheric CO2 levels; ventilation or artificial enrichment of CO2

10. Micro Nutrient Availability

11. Additive/Supplement/growth accelerant types and availability Root health enhancements (mycorrhizae, symbiotic bacteria, etc.)

12. Air Humidity levels (some varieties are more susceptible than others)