One thing we can never be certain of when living in the British Isles is whether we’ll have a hot summer or not as let’s face it, no 2 consecutive years ever seem to be the same these days! One thing we can be sure of is that temperatures will rise, by how much, who knows, but all indoor growers need to be prepared for the warmer months ahead.
If LED’s are your grow light of choice, you’ve already eliminated one of the main heat sources which can help grow room temperatures rise. If you’re using High Pressure Sodium (HPS) or Metal Halide (MH) lamps, like the vast majority of growers still do, then you’ll be fully aware the amount of heat they can produce. During the winter months, this can be helpful in rising grow room temperatures, but during the summer, can be a hindrance to say the least!
There are however a few ways to overcome this…
1. Use an Air Cooled reflector or Cool Tube. Yes, these can have a reduction in the light output, some say by around 10%, but, they not only help extract unwanted warm air making it easier to maintain grow room temperatures, they also allow the light to be physically placed a lot closer to the plants canopy, thus negating any output loss.
2. If using a more traditional reflector, such as a Euro or an Adjust-A-Wing, try moving it higher than it usually would be, even just a few inches might be enough to help with air flow, keep temperatures down and it won’t affect the final yield as dramatically as some growers think.
3. Use an Oscillating Fan (or fans) between the light and the top of the plants canopy. All grow rooms should be using these anyway to help keep the air moving, but during the summer if positioned correctly, can help to reduce the temperature. Some of our customers place the fan just under the canopy, blowing up towards the light, while others have it blowing between the light and top of the canopy.
4. Switch the Lights On period to during the night, rather than following the natural hours of daylight. The night time is generally a few degrees cooler than during the day, which might just be enough to drop the grow room temperature to the desired level.
It’s not just lights that can generate excessive heat. If using an intake fan for fresh air, make sure it’s being drawn from a different room, or location, that’s significantly cooler as this will help lower the overall temperature. Under no circumstances, especially during summer (unless using a passive intake), should air be pulled in from the same space as the grow room.
Thermostatic fan speed controllers are also a worthy investment as the desired temperature can be set and the fan (or fans) will be adjusted automatically to help maintain it, too hot and the fan speed will increase, too cold and the speed with decrease. If budgets don’t stretch to a fully automated controller, manual fan speed controllers can also be used, but as you can’t always be in your grow room, these might become a hindrance more than a help if there are any spikes in temperature.
If growing using a hydroponic or an automatic feeding system (such as an AutoPot) that require nutrient solutions to be pre-mixed and stored in a water tank (which is usually placed in or very close to the grow room), attention should be paid to the temperature. Too high and the solution will become an ideal breeding ground for algae, which also reduces the amount of available oxygen, and will lead to unhealthy plants producing poor yields, or in a worst case scenario, root bound diseases such as pythium.
There are a couple of ways to combat this. If money is no object, then a Water Chiller is the obvious choice, starting at £300, they aren’t cheap, but will give peace of mind that the temperature of the nutrient solution will be constantly maintained. If a more DIY approach is preferred, a great tip is to fill empty bottles (your old nutrient bottles will do) with water, put them in the freezer, once frozen, place them in your nutrient tank. This will help lower the temperature but you might need to have several bottles in constant rotation so when one has thawed, it can be quickly replaced, rather than having to wait for it to freeze again!
The warm days can also bring with it the increased chances of bugs invading your grow space, a simple solution is to cover all intakes with Bug Barriers. Made from fine mesh, they allow air to flow, but will stop any unwanted critters from entering the grow room. An even cheaper way is to cover intakes with ladies’ tights (for the fashion conscious, denier rating or colour are unimportant), but be warned, they aren’t as robust, or long lasting as Bug Barriers and an eye should be kept on them as any little rips or tears is an open door for a pest invasion.
So there you go, a few tips to help keep your grow room at the optimum temperature, your plants healthy and producing high yields during the warm summer months.