High temperatures during indoor growing. How to avoid them?
Although summer is now irretrievably behind us, the heating season is already in full swing. That is why the topic of high temperatures remains highly relevant, as they can quite easily become the cause of restricted growth or flowering in your precious plants and, in the worst case, even permanently damage them. In this article, you will learn how and why to deal with high temperatures inside a grow tent or room. And it will not be only about air temperature. Among other things, we will also remind you why substrate temperature is important. You will also learn the difference between temperatures that suit the roots and the above-ground parts of plants.
Are you wondering why plants every year tolerate extreme temperatures so poorly, not only outdoors during summer, but also in overheated rooms during the winter months? It is because if the environment in which they grow is too hot, the plants can no longer cool themselves sufficiently through the process called transpiration. Simply put, they cannot keep up with releasing water, and the hot air causes them to dry out relentlessly and gradually deteriorate. This is, of course, a problem that needs to be prevented or at least addressed in time. It is also worth noting that plants grown outdoors are partly adapted to summer heat, because they cannot escape it in nature. As an indoor grower, however, you can take the right steps so that your harvest never again suffers from high temperatures and hot air.
What can high temperatures in the tent cause?
Otherwise, nutritional deficiencies will sooner or later appear (see separate article: Symptoms of a deficiency of important nutrients), or the signs of their undesirable excess. In addition, plant growth usually slows down significantly, and the leaves may also die off. If the leaves do not die directly in such cases, they usually curl and dry out. Once your plants start to wilt, things are really serious. That is almost the end, when irreversible degenerative processes occur and the harvest is permanently devalued.
Dealing with high temperatures in indoor growing
Now let us focus on the most important factors related to temperatures in the growing space within indoor plant cultivation, which you can influence as a grower.
You may already know that especially powerful discharge lamps emit a considerable amount of heat into their surroundings in addition to light radiation. Although many growers still swear by classic discharge lamps, whether out of habit or for other reasons, modern LED lamps are gradually, but surely, overtaking them on the grow lighting market.
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LED grow lighting can work with electrical energy more efficiently, converting it into light radiation. Thanks to this, increasingly popular LEDs do not raise the temperature inside the grow tent nearly as much as discharge lamps do. You can read about other differences between discharge lamps and LED fixtures, such as the composition of the light spectrum or electricity use, in a separate article: Growing under artificial lighting: HPS vs. LED.
The good news is that you can at least partly control the heat generated inside the grow tent when using powerful discharge lamps. On the one hand, you can temporarily reduce the light output, because plants suffering from excessively high temperatures will not be able to make use of high PPF values anyway, but above all, when using a discharge lamp, you can take advantage of air-cooled reflectors or COOLTUBE-type reflectors.
- VENTILATION AND AMBIENT TEMPERATURE
The temperature inside the growing space is, of course, primarily determined by the temperature of the surrounding air that is brought into it. Indoor growers are not some special species that likes freezing at home in winter, but in some cases it is still worth lowering the temperature in a comfortably heated room by at least a few degrees. In summer, there is nothing better than air conditioning, which is not among the cheapest equipment, but especially second-hand it can become a more accessible solution that will significantly make home growing of herbs, fruit or vegetables easier for you. Other proven tips include switching the grow lights on only at night, when temperatures are usually lower. And if the layout of your flat, or the placement of the grow box, allows it, bring fresh air into it directly from outside using an intake fan connected to ventilation ducting.
This brings us to the flow of fresh air around the plants, which is unnecessarily underestimated in indoor gardening, at least at hobby level and in the early stages. But remember that the more fresh air you “move” through the growing space, the better the plants grown inside are able to cope with higher temperatures. It is important that the air being extracted from the grow room does not mix with the fresh air that is still flowing into the growing space. It would affect both its temperature and humidity. The quality of a well-designed ventilation system is simply essential. On this topic, we also recommend the following separate articles:
And how can you ensure that the hot air in the grow room does not stand still, but instead keeps flowing around the plants? Simple! That is exactly what circulation fans are for, as they are indispensable helpers for every indoor grower, and cheaper versions can be bought for literally a few pounds. You can learn everything important in a separate article: How to choose a circulation fan?
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- HUMIDITY