Hot Weather Grow Room Management

Hot Weather Grow Room Management

How To Help Hydroponic Crops in the Heat


As a trend, summers are becoming hotter–for longer, necessitating a strong set of hot weather grow room management skills. Sizing and performance allowances for growing equipment such as fans, chillers or air conditioning units may prove to be inadequate.  Rules of thumb for sizing such equipment may have changed.  While many hydroponic growers operate indoors, the situation is not entirely immune to issues from increases in outdoor temperatures.

with good management, crops stay healthy in hot weather


Heat stresses can lead to poor quality, lower yields, disease problems, insects, higher power bills, increased water use or even crop failure.  Commercial growers can’t afford to take the loss in competitive marketplaces.


Water management on a commercial scale may require extra attention. Warmer water has a higher chance of having microbial contamination and municipal supplies may be prone to algae blooms.  Holding tanks and reservoirs may be more prone to issues as a result. Using a chiller to maintain 68 deg F reduces the incidence of unwanted biological activity. Cooler solution temperatures also potentiate higher Dissolved Oxygen (DO) levels for healthier crops. Optimal temperatures may be maintained in holding tanks by way of commercial grade hydroponic chillers.

Hydro Frost Hydroponic Water Chiller 3Hp
Hydro Frost Hydroponic Water Chiller 3Hp

Additions of hypochlorous acid into water supplies and hydroponic reservoirs are recommended at all times, however, dosages may need to be increased in frequency or concentration during hotter times. Clear Line and UC Roots are highly effective in hot weather grow room management in this capacity and are entirely safe to use as directed.


There are a variety of factors that affect the temperature inside greenhouse and climate controlled grow rooms:




Keeping the climate controlled interior insulated from the outside is critical for operating efficiency, especially in terms of HVAC power usage. A poorly insulated growing operation is prone to temperature fluctuations which can lead to issues with humidity and lessened crop performance.


Building Type


Some building designs work better at preventing overheating from solar exposure than others.  For example having some dead air space between the roof and interior surfaces can help to trap and redirect heat for less impact on interior temperatures. Metal clad surfaces can reach very high temperatures on hot sunny days.


Solar Exposure


If a building is 100% exposed to the sun it is prone to overheating.  If shaded, even partially, by trees, surrounding buildings, etc there is significantly less solar radiation hitting the building.  Additionally, trees can provide some microclimate cooling with evaporative transpiration, as can ponds or surrounding bodies of water.


Rolling Black Outs


In some areas power demand for air conditioning exceeds what the grid can supply and there may be outages. Naturally, this can be highly detrimental to crop productivity and the ability to maintain optimal temperatures. It may be a prudent investment to have stand-by power available.


Type of Grow Lighting


Some lighting engineers will state there is very little difference in how much heat is generated in a 600 W LED lighting fixture VS 600 W HPS.  Most growers find LED grow lights help keep the room cooler.  Also keep in mind typically fewer watts of LED are required to provide strong light for growth in the same given area.  Additionally, LED grow fixtures dissipate heat differently; it’s more evenly spread VS HID lighting.


Utilizing LED lights is often favorable in hot weather grow room management vs HID lighting sources.


Exchanges of Outside Air


In hot weather, anytime a personale door or shipping receiving door is opened, it has the potential to add to the heat load on the growing facility’s HVAC system. Limiting air exchanges with double doors i.e. corridors and using air curtains can help keep unwanted air outside where it belongs.


Some growers use fresh filtered outside air for timed exchanges in sealed grow rooms to help prevent any risk of phytotoxicity in the growing environment. If drawn from outside in hot weather it may contribute heat load or stress a hard working HVAC system.


Things to watch for in the growing area for better hot weather grow room management, as these factors may change with direct consequences to the crop.


Paying attention to growing factors yields healthy harvests, even in hot weather

For the Residential Grower


  • run at night, 
  • use dimmers in lighting systems, 
  • reservoir chiller, 
  • HOCl additions (UC Roots, Clear Line), 
  • insulate


For Commercial/Professional Growers


  • insulate, 
  • chillers + air pumps in separate areas (as appropriate), 
  • ORP management, 
  • VPD management, 
  • extra attention to sanitation