GREENHOUSE VENTILATION AND TEMPERATURE: WHY IT’S IMPORTANT
by Adrian White
20 December, 2021 by
GREENHOUSE VENTILATION AND TEMPERATURE: WHY IT’S IMPORTANT
Lucija Johum

Greenhouses tout a wide range of accessories. You can turn on the lights with various lighting options, or darken the skies to trigger flowering with light deprivation. Or, opt for some heating accessories to warm things up – while inversely, you can keep things cool with a variety of additions and tricks.

When it comes to accessories however, greenhouse growers will tell you that the game is all about temperature, for the most part. Rises and falls in heat and cooling are the most common elements you’ll wrangle with, followed by humidity, CO2 levels, sun exposure, and more. Not only are they likely to fluctuate the most in your structures, temperatures can also have the most beneficial impact on your plants within – though if unmanaged, they can be detrimental if they go too far out of range, especially in overheated greenhouses.

Fortunately, the world of greenhouse accessories equips you with a wide arsenal of tools to manage temperature, but the most basic and affordable are vents and ventilation. In fact, very basic ventilation is cleverly built into nearly all models, as it is such an important part of greenhouse operation and plant health. When choosing, designing, and building your greenhouse structure for the season, having ventilation of some sort in place is one of the easiest, most affordable ways to handle this pivotal factor – along with other factors related to temperature to some extent, such as humidity.

HEAT EXHAUSTION IN PLANTS

As any professional grower knows, plants of all kinds have specific temperature requirements to thrive. Combined with another known fact – that greenhouses will raise temperatures rapidly on their own, particularly on sunny days – this can spell impending disaster for certain crops. Excessive high temperatures can also severely dehydrate plants without the proper ventilation.

Symptoms of heat stress include:

  • Wilted, limp foliage

  • Burnt or dried appearance

  • Yellow leaves

  • Fallen over plants

  • Dropped leaves or flowers

  • Bolting (premature flowering)

  • Spontaneous plant death

  • Excessively dry soils

DIFFERENT NEEDS FOR DIFFERENT PLANTS

Of course, the degree to which plants can be affected by excessive heat and dehydration depends on what variety they are. Some tropical or desert-native plants for example (such as cactuses and succulents) will be able to withstand huge temperature climbs with no problems. However, most other types (including vegetables, flowers, and perennials) will suffer from escalating heat in some sort of way – and you will often know it just by appearance. 

How to save heat-sensitive plants? Ventilate. This allows you to expel some of the hot air trapped within your greenhouse, and welcome in cooler air to prevent heat exhaustion. In the process, this also helps keep moisture from evaporating out of soils, which will compound the stress on your crops. 

Other than ventilating (which you should do immediately if you notice heat stress), there are a handful of other ways you can prevent plant damage or death in these instances. This includes an increase in watering to make sure that soil is constantly moist (though avoid waterlogging) among other approaches. Lack of moisture due to heat excess is even more stressful, though use discretion depending on the specific plant’s watering needs.

SEASONAL CHANGES

Especially in seasonal climates where temperature changes can be drastic, having the option to ventilate is crucial. Seasons like spring or autumn can hike up temperatures on sunny days, which puts heat-sensitive cool-season crops (ideal for growing during these seasons) in peril. If you rotate plants or intercrop in your greenhouse too, this adds another variable that calls for temperature regulation – all sorts of combinations of plant needs and greenhouse temperatures will demand ventilation (or, not).

Summer is not the only season when overheating in a greenhouse occurs. Even on unseasonably warm and sunlit days in winter, it’s well-worth it for you and your plants’ sakes to check on temperature, and to make sure it hasn’t climbed too high indoors (yes, even if you’re feeling confident – it never hurts to check). Regardless of cold ambient outdoor temperatures, greenhouses are built to heat up – and high temperatures can get away from even the most experienced of growers.

TIME OF DAY MATTERS, TOO

Farmers and gardeners should take note that times of day bring temperature changes as well. During any season, temperatures typically drop at night, whether it’s summer or winter. On warm and/or sunny days, ventilation of some sort should happen in the morning to prepare for midday, when temperatures usually climb to their highest all day (though not always).

During hot summers, it may be advisable for greenhouses to be vented all night and all day. On the other hand, winter most likely requires greenhouse operators to keep vents closed both night and day. All this can change though: unseasonably warm days might occur in winter, autumn, or spring during the day, while cool temperatures can happen on a summer night. 

Greenhouse growers should always keep an eye on the forecast and what general temperatures to expect, keeping vents open or closed based on what is needed. Further, temperature changes don’t always follow this rule: sometimes, temperatures are higher at night than they were all day (and vice versa), though this is unusual. If you haven’t done it already too, make sure you have a thermometer somewhere in your greenhouse to be able to watch temps accurately, if you don’t have any other method in place already. 

CHECK TEMPERATURES AHEAD OF TIME

The best friend of any agriculturist is a reliable weather report. Staying ahead of the weather and making note of temperatures helps the most adept of growers anticipate the ventilation needs of their greenhouses. The closer watch kept on the forecast, the better: even if certain temperatures are predicted way ahead of time, these can still most definitely change without notice, especially the farther out a forecast goes.

Have a favorite online weather site or app? Keep it up on your computer or mobile at all times if you run a greenhouse, and check it often. Get acquainted with the limits of what your plants can stand – both hottest temps, and coldest ones as well – and stay near your operation on days that seem to be of most concern.

THE ACCESSORIES THAT HELP YOU

Enough of all the factors involving temperature and ventilation. What methods of ventilation are actually out there that you can incorporate into your greenhouse to make this happen? What ventilation accessories are available? The answer: plenty.

ROLL UP SIDES

Some sort of roll up side is built into almost every greenhouse model. In addition to opening doors, lifted sides help improve airflow and exchange, while still keeping the top intact over plants for a protective environment. There are some very basic roll up side options: these simply involve attaching and detaching the plastic sides using channel and wiggle wire, a very popular mechanism.

Others may involve manual cranks to make the opening and closing processes go much more quickly and smoothly to save time and effort. Channel and wiggle wire is a time consuming process, so using cranks help the busiest of growers save precious time for putting their focuses elsewhere in their operations. For especially busy growers, some cranks can be automatic, operated at the simple push of a button. 

VENTILATION SYSTEMS

Take things up a notch with a more sophisticated ventilation system. Much like any building, a combination of installed vents with fans not only improves airflow in your structure, but can help with the powers of temperature control and prevention of heat issues (in addition to issues with cold as well). Often times, vents and fans might be part of a more technological way of heating and cooling a greenhouse with advanced controls, though they don’t have to be.

For the very best passive control, combine roll up sides and a ventilation system in one structure. No additional costs need to be invested into the system to run it, thus providing an affordable, one-time investment on your building to help keep it cool. Installation of vents is fairly straightforward, while the prices of most basic vents are cheap. 

CONTROLS

Got the budget? A controlled ventilation system – such as one powered by a thermostat or other controls – can be a very convenient option. At the touch of a button or dial, your setup will be effortlessly ventilated for the benefit and health of your plants, so you can keep concentrating on other important parts of running your business (or hobby).

For even more convenience and control, consider a solar-powered vent. Substantial sun exposure – the main factor that triggers heat buildup in a greenhouse – makes these vents open and close on their very own, creating airflow and letting heat escape. This is another great option for the busiest of operators.

SMART SYSTEMS

The ultimate in ventilation convenience is found in a fully-functional, multi-faceted smart greenhouse. These top-of-the-line systems cover everything ventilation-related for you: computer software gauges and keeps track of temperature, among many other elements in your setup’s environment. If temperatures reach certain pre-programmed or set thresholds harmful to your plants, the smart greenhouse responds with all the required, fully automated adjustments connected to the sensors to expel excess heat or close up to protect from cold.

Even better, these functions – temperature, ventilation, and more – may all be monitored from a convenient mobile app connected to the software. With this app, the grower can also decide to completely automate ventilation, attach it to a timing mechanism, or manually operate the system, each possible remotely. For the best choice of effortless growing, easy ventilation, and benefits to your plants and schedule, a smart greenhouse provides the ultimate option for temperature regulation.

VENT A LITTLE

Among all the accessories to consider for your greenhouse, ventilation systems are always the best (and smartest) ones to strategize first. Temperature is the aspect of your growing environment that you’ll be working with for the support and well-being of your plants time and time again. Additionally, of all options for regulating temperature, vents of many types provide a passive and generally cost-free solution to letting trapped air escape, and to prevent heat from rising.

For larger operations and busier growers, advanced controls and systems are available to both manually and automatically vent covered structures, so you can continue working on your top agricultural priorities. No matter the size, scope, or aim of your greenhouse system – whether for personal pleasure or profit – always incorporate some type of ventilation. From simple roll up sides to the most modern greenhouse technology of the day, venting your operation is well worth it, and your plants will thank you.

GREENHOUSE VENTILATION AND TEMPERATURE: WHY IT’S IMPORTANT
Lucija Johum 20 December, 2021
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