12 tips to keep the temperature low in the summer

12 tips to keep the temperature low in the summer
Adam Parsons

A hot summer? Great, but if you're a indoor grower, you quickly have a problem. Check out these 12 great tips to keep that temperature under control!

Who doesn’t enjoy a nice fat spliff on a beautiful sunny summer day? The sky is blue, the birds are singing and the temperature is rising.

Great, but if you're a indoor grower and you’re not prepared, your grow could go to waste with those hot temperatures. Some indoor cannabis growers even shut down the grow show entirely during a hot summer.

That’s all well and good if you can switch to outdoor cropping, but for most, it's indoor weed or no stash. Fear not the sunlight dear reader. We’ve got 12 tips for indoor growers to help you cope with a hot summer.


Whether you are ganja farming with a brand name grow tent or a DIY grow room, it’s crucial for environmental control to ensure you get the right fans in the right place. Make sure to get fans, that are large enough for your grow show.

If mounting fans in the roof of a grow tent, make sure the frame of the tent is strong enough to handle the weight and the fan is secured with chains and/or cable ties. It’s better and safer to have more powerful intake and outtake fans running on a low-mid setting rather than constantly running small fans at maximum capacity.


An air conditioner is the easy elegant solution to the excessive grow room heat, that a hot summer can bring. However, if you happen to live in a cooler country, your home probably has central heating rather than an air-condition system.

A portable AC unit will suffice and might be available from the local grow store, if not, you’ll find one for sure online. The only downside of using air-condition is the increase it makes to the power bill.


The addition of CO2 is proven to fatten up buds and boost marijuana yields. This heavy harvest technique is best suited to commercial grow ops and very popular with the more experienced grower.

Moreover, higher levels of CO2 allow for a higher temperature in the grow show and it is a way to capitalise on higher temps.

However, for the home grower probably sleeping in the bedroom next door, exercise caution and stick to a simple passive system rather than dabbling with CO2 tanks.


Old school HPS and MH lamps emit a great deal of heat as well as light. Curb that excess heat and keep on growing year-round by air-cooling those HID lamps.

All that’s required is an additional fan and some ducting attached to an air-cool reflector to suck out that heat from the grow tent.



A simple trick to cheat the daytime temperatures is to grow after dark. Night time temperatures are naturally lower than during the day and your grow light dictates the day-night cycle for your plants so they will never know.

Also, running the electricity off peak should make a saving on the power bill too.


A well insulated and properly sealed off grow room is always easier to maintain optimal environmental conditions. The objective is to cordon off the effects of the weather outside and maintain a suitable interior microclimate.


It’s advisable to mount your ballasts, control boards and other electrical contacts outside of the grow tent on a wall. Good housekeeping when it comes to electronics won’t just shave a few degrees off temps it might just save your life.

All ballasts and grow equipment build up heat and keeping them outside of the grow area and off the floor is the smart setup.


Maintaining good air circulation inside the grow show is relatively easy to accomplish and simply adding an oscillating pedestal fan, and/or some clip-on fans if space is tight, can make all the difference during a summer heat wave. A gentle breeze will keep cannabis plants cool and help them stay rigid.


Desperate times call for desperate measures. If cash is tight and the heat is on, the cheapest way to lower the temperature a bit is with a bucket of ice or two.

You can simply fill up a few empty 2l plastic bottles and stuff them in the freezer for a few hours or if you have an American Freezer empty out that ice cube dispenser into a bucket and fill it up again.


Bends and kinks in your ducting will put a greater demand on your fans and reduces their efficiency. Smooth out that ducting and try not to have any twisting or bending. If the ducting connected to your air-cooled reflector or outtake fan is bumpy and poorly connected, heat is going to build up.

Similarly, loose fitting sagging ducting on an intake fan will reduce the volume of fresh air. Get a fresh roll of duct tape to secure connections and keep that ducting straight.


Dimmable ballasts give the indoor greater flexibility during those hot summer months. If the temperature gets crazy hot it’s possible to dial down the output of the grow lamp.

Of course, this will reduce the lumens as well as the tempemperature and yields will subsequently be decreased. This is not a perfect solution, but dimmable ballasts can facilitate a scaled-down indoor summer grow show, instead of a total shut down.


LEDs are the perfect remedy for the indoor grower hell-bent on cultivating indoors even when the weather outside is positively Martian. The beauty of LED lighting is, that most of the energy is converted to light rather than heat, which ensures cool running.

At present, the only real drawback with the latest generation of LED systems is the price. But if you’ve got the cash, LEDs are a great long term investment in your grow op and once you gain a little experience expect bigger yields and higher potency buds.

That’s your lot and if the above dozen tips don’t help to reduce grow room temps in a hot summer, you can always relocate to Alaska and pretty soon you won’t even remember what warm feels like, they’ve got legal weed there too now.

Adam Parsons
Adam Parsons

As a professional cannabis journalist, author, and copywriter, Adam has been writing about all things psychoactive, CBD, and everything in between for a long time. In an ever-changing market, Adam uses his BA (Hons) Multimedia Journalism degree to keep in stride with contemporary research and contributing worthwhile information to all of his projects.