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22 Top Tips to Help Cool down your indoor Garden

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It is clear to see when summer months are just around the corner, especially when you work in a grow shop. Suddenly as early as March you can get a surge of customers coming in and inquiring about ways to cool down their grow rooms. In fact some indoor growers opt to stop growing altogether during the hot summer months.

The majority of growers that face heating problems in early spring, tend to have usually just assembled a grow room without having carefully planned or measured their room or their apparatus correctly. Others may just need tweaking or an addition of some extra equipment specifically designed for grow room heat reduction.

The GoGrow team was asked to jot down any tips or remedies on this subject and the findings are as follows:

  • 1.Correct intake and outtake fans - Air flow is vitally important especially when constructing a grow room. Fan size will depend on the size of your room or grow tent. Please see previous article.

  • 2.Air Conditioning - The temperature of your air is as important as having good clean air. Trying to establish the correct growing environment can literally cost you lots of time, money and stress you out. But having a air con unit (unit will again depend on the size of your grow room) can help you immensely. Something else to consider is whether a one piece unit or two piece air conditioning unit is needed. Air con units are perfect for the really hot periods in summer and also good for winter if it is too cold outside. Remember Air con units will help to also to counter the heat build up created by your bulbs, ballasts, pumps, CO2 generators and other assorted electronics as well as cooling your air.

  • 3.Opticlimate - This unique bit of kit is spear heading the way grow rooms think about and create their grow rooms. The Opticlimate has over the past few years answered many growers’ problems with room environment and achieving optimal conditions. As good as it is, we do believe to run these units efficiently you need to be good with engineering or know a man who can. It is in basically a kind of air con but uses water to cool it down and also helps to feed in Co2 and adjust and maintain your room’s optimal environment.

  • 4.CO2 - Co2 helps to keep your temperatures lower than normal but the usage of Co2 can be tricky. But Co2 only really helps to cool the environment when temperatures exceed normal temperatures. Higher Temperature is Okay - Maintaining 1200-1500 PPM (part per million) of CO2 in the grow area allows growers to keep temperatures much higher than normal. For growers with hot bright lights, this makes it easier to keep temps at a range their plants will like.CO2.

  • 5.Air Cooled Lighting - Air-Cooled lights work by using extraction fans to pass air continuously over the lamps and then exhausting this warm air out of your grow room via aluminium ducting. If you use acoustic/insulated ducting on the outlet this will help cool your grow room even more. Air cooled reflector.

  • 6.Water Cooled Lighting - It is more efficient to cool your lights with water than air cool them. The cooling is also more effective allowing the unit to be placed closer to the plant canopy. Water cooled lights also reduce the requirements of an air conditioning system. To conserve water the units are generally cooled using a reservoir and water pump. Depending on the size of the reservoir you may require a water chillers’.

  • 7.Run @ Night - Many indoor growers opt to have their lights on during the night. This is an excellent way of keeping temperatures down. At night temperatures are subsequently lower than during the day, therefore especially in the hot summer months it is best to suck in cool night air opposed to blistering hot day heat etc. On a plus side this transition also allows your electricity bill not to soar, as electric on off peak times are cheaper to run.

  • 8.Room Insulation - A well insulated room can help you to control your grow room temperatures far more easily. For example if your grow space is in your loft and your roof is exposed and your growing area is not cordoned off then your grow room is far more susceptible to being influenced by the weather outside due to its location.

  • 9.Ballast & Control Board placement - If you can have your lighting ballasts and all your electrical devices or grow room control board for example outside of the actual growing area, this can help to keep temperatures much more manageable.

  • 10.Hygrometers - These days all good grow rooms and indoor gardeners have hygrometers, but to get a true indication, the more the merrier. Try to have a minimum of three, one up high, one in the middle and one lower down. This will help you to identify cold spikes or heat pockets etc.Hygrometer.

  • 11.Good Inner Grow Room Circulation - Some growers prefer lots of little clip fans some like stand fans others have wall mounting or floor fans. Again the more the merrier but diversity is key. For example try to alternate different fans blowing alternately as the wind outside never blows the same way for too long. Fans with oscillation or fans that have a circulating and moving louvre are ideal. If possible try to create a vortex of sort by having a fan in each corner, each one face the other helping to create a circulating vacuum of air. Fan circulation.

  • 12.Light movers - Light movers are another great way to spread heat evenly in your grow room.The light is spread around more, which means less of your leaves and flowers are shaded out. This ultimately eradicates having hot spots in your grow room.

  • 13.Reservoir Chillers - Hydroponic growers must have control of their reservoir temperatures. Otherwise if temperatures are too hot it can be very detrimental to the health of your plants. Over heating your nutrient reservoir can lead to root rot and issues with oxygen levels that can harm or even kill your plants. Purchasing a chiller for your reservoir will alleviate this problem swiftly.Chiller.

  • 14.Reservoir Placement - If it is possible to leave your nutrient reservoir outside of your heated grow room this can also help your to keep temperatures cooler.

  • 15.Ice Bottle - Placing a 2litre frozen bottle of water into your nutrient tank also helps to cool your reservoir. This is more of a make shift solution and ideally if your temperatures continue to rise then a chiller will be a more solid and reliable solution.

  • 16.Ducting - Keep the ducting in your grow room as straight as possible and down to a minimum. Any bends in the venting tubes will reduce your fan power by 5% so less is more here; also having insulated ducting helps as well. Ducting.

  • 17.Iceline - Iceline is a hose specifically designed to combat the build up of excessive heat build up. Made from the high quality materials, Iceline has a white outer layer to reflect heat and a black inner layer to absorb U.V. A lower temperature in the nutrient solution means increased levels of oxygen and a reduced risk of root disease, as well as more stable pH and EC.Iceline.

  • 18.LED Lighting - LED lights are a great way in which to keep your temperatures down especially during the hottest months of the summer. Do your research as LED do work differently and do not emit enough heat for your grow room therefore before you go out and change all your lighting for LED’s. Remember that during the winter months your garden will suffer if there is not enough heat so it is a fine line and has to be thoroughly thought through.


  • 19.Digital Cooling Humidifier - A cheap way to reduce heat and also add moisture at the same time is to get a digital cooling humidifier. These devices spray out a fine mist spray from a water tank that needs to be refilled. They’re available in many different sizes and applications for use in almost any grow room.

  • 20.Ice Box Intake - These are fairly simple to assemble and work best if made from an old picnic cooler type ice box or try the cheaper alternative with a polystyrene ice box/container. Both sides of the cool box will need to be cut, one side to fasten your ducting and ducting flange size. The other side of the ice box is for air to be sucked in from; therefore a grill type mesh sized cutting is required. Fill the ice box with ice but beneath your cutting holes, as remember you will be emptying this ice as water later. Now affix a Y splitter onto your intake ducting. You will now have two intake channels; one will be for in taking your fresh air source and the second to be attached to the flange end of the cooler box. Now depending on the size of your box and how hot it is will determine the length of time this make shift cooling aid will work for, but after testing it, it is worth doing if you cannot afford a more reliable option. Hopefully you find the information listed as useful for solving any overheating problems over the hottest of the summer months.   

  • 21. Dimmable Ballast - When your grow rooms temperatures do get too hot to grow, you can always run your 600w lights onto the lower variation of 400w for a while. The dimmable ballast allows you to do this, along with 30% cheaper running costs compared with a traditional magnetic ballast. Adjusta-watt.    
  • 22. Switchbox - All In One 4L Switch Box is a complete control unit for your grow area. It controls your lights, heater and two fans. Hence the name All In One.
    This brilliant bit of kit has an amazing innovative feature, named TempProtector, this has been fitted on the Switch Box so that your grow room/area never exceeds your personally set temperature. It does this by switching off your lamps, one by one until the temperature lowers. Then they will re-ignite after 30 mins due to the built in timer aptly named the Delayed-StartUp. This added innovative feature ensures that your lamps do not attempt to re-ignite whilst they are still too hot. But no matter what the temperature is, one lamp will always stays on.
    The Switchbox made by SMSCOM is also equipped with Dual Digital fan software, which controls two fans by the means of motion flow technology; the Switch Box will start scanning the room and find the correct running speed for your fans. SwitchBox.


  • Not a cooling tip but more a growing tip for higher temperatures, is if you incorporate silicon with your normal feed you will be able to grow your plants in hotter conditions. This is due to the silicon as it helps your plants to become more resilient and remain healthy even if your temperatures rise up to 40c. Please feel free to visit us at the shop to discuss the design or even set up of your indoor grow room. Come and visit us at the shop: Unit 1 Mill yard industrial estate, Columbia avenue, Edgware London Ha8 5ef.