How To Control Substrate Temperature in The Greenhouse

How to control substrate temperature

Whether it is container culture or bag culture, the space for the root system to extend is limited, and its range is much smaller than that of soil cultivation. The advantage of this is that it saves the substrate and facilitates control of the rhizosphere environment; the disadvantage is that the substrate is small, has limited buffering capacity, and has limited control over extreme temperatures. Therefore, under extreme temperature conditions, substrate temperature control is an important link in determining the yield of substrate cultivation.
Extreme temperatures of too cold or too hot will cause direct damage to the roots of substrate-grown plants, resulting in uneven rooting.
Affected by the ambient temperature, root growth will cause uneven distribution of yin and yang. The temperature of the substrate is controlled, so the root system is relatively evenly distributed in the pot.
Plants have a certain range of temperature tolerances. However, too low or too high temperatures will have an impact on plant root growth. If substrate temperature reaches 40°C for 5-6 consecutive hours, indirect damage occurs, including growth cessation, impaired hormone signaling, inhibition of nutrient absorption, and increased incidence of disease.
Direct damage is a more serious problem, as long-term exposure to extreme temperatures will eventually damage the root system beyond repair, resulting in poor health and appearance of the plant material. Direct damage will cause the plant to develop symptoms associated with indirect damage and may begin to wilt, especially at the roots.
Extreme temperatures in substrate growing barrels can have devastating effects on plant health and quality if sustained for an extended period of time. As the planet warms, more plant heat stress and crop damage are occurring around the world. Temperature damage is also an issue even in areas with milder climates. More and more people are paying attention to how to deal with the extreme temperatures of the substrate in the container.

There are many ways to alleviate extreme substrate temperatures. In production, you can add shading nets to cool down, or use semi-buried substrate barrels underground to take advantage of the natural insulation capabilities of the soil to cool down.
Irrigation can have the effect of cooling the plants and substrate. Circulating irrigation has proven to be an effective means of regulating temperature. Of course, afternoon irrigation provides only limited relief from the heat, lowering temperatures by only a few degrees in extreme cases.
If the pipes are exposed, the water flowing out will also be very hot, negating most of the cooling effect. However, watering during the hottest part of the day goes against best management practices. Because watering to control temperature can adversely affect crop growth.

In summer temperatures in many places, substrate temperatures above 38°C can often be detected, and in extreme years, substrate temperatures can even reach 66°C! So keep growing buckets close to each other or try to use lighter, brighter-colored containers instead of black growing buckets to mitigate extreme substrate temperatures.
The black container matrix exceeded the critical temperature of 38°C for approximately 9 hours per day, while the white container exceeded 38°C for less than 2 hours. So while high temperatures may be unavoidable, it's worth the effort to shorten the duration
However, be careful when using white containers. The interior needs to be lined with black plastic to limit light penetration into the root zone, hindering root growth and causing algae growth.