Today's Gardener (todaysgardener.com) is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. This site also participates in other affiliate programs and is compensated for referring traffic and business to them.
Considering the ongoing process of global warming, there will be no place in this global greenhouse where cooling down won’t pose a problem. Therefore, I’ve decided to share some tips on how to shade your greenhouse and keep it cool in the summer at a desirable level.
Whether you’re already facing this issue or fear you will in the future, these pieces of advice will definitely come in useful!
It’s common knowledge that glasshouses are meant to keep heat within but this can really turn into a drawback in the dog days of summer!
Bear in mind that the temperature inside a greenhouse is always from 20 to 30° higher than the one of the outside air! In case you’re wondering – the optimal temperature for a greenhouse is between 68 and 75.2° F. Anything exceeding 80.6° C can be fatal!
In order to be able to keep track of how hot it is inside, put in a min/max thermometer. Pay attention not to situate it in shade or direct sunlight.
If heatwaves strike, keep cool and make sure to apply the following methods for your indoor garden to do the same!
Make Use of Plants
Placing large-leaved plants such as grapevine or fig trees on the west side of the greenhouse or planting tall evergreen trees that cast spotty shade nearby can be beneficial. They can block the intense afternoon light whilst letting the so-wanted morning one pass through.
Be warned that if you don’t pick deciduous trees for the outdoor shade-casters, you may do more harm than good because you want no shadows during cold months!
The foliage of the indoor ones serves as a cooler in two different ways – shading the soil below thus reducing its temperature and consequently the one of the air, and “sweating”, i.e. transpiring moisture which then evaporates cooling the surroundings.
Similar to adding ice to your drink, emplacing a metal tank full of cold water could significantly reduce the temperature of the greenhouse’s content!
If you drench the tables, pathways and any other heat-retaining surface in the greenhouse twice or thrice per day, you will nip overheating in the bud hindering it from doing the same to your plants! In a nutshell, the evaporation will humidify the air cooling off the flora in your indoor garden and impeding the development of some pests.
Don’t let your green friends be thirsty! If you need a couple of glasses of a cold beverage on a roasting day – so do they! Plants require water so that they could cool themselves down by “sweating”, that is to say releasing moisture through the leaf pores. Ergo, if you notice some withering leaves, know that your verdant buddies are suffering from a heatstroke!
If you apply an evaporative technique in an area with humidity lower than 50% – you’ve aced it! A swamp cooler or a cooling wall combine the use of water and airflow to cool down the inside air. Namely – the cooler drives the hot air through a pad riddled with channels and maintained moist by a constant supply of water running down it. The transition from liquid water to vapor can consume up to 20 degrees!
You can even get a multifunctional portable cooler! Personally, I prefer homemade stuff so I’ve assembled one myself to save some time– you’ll only need some PVC pipes, a water tank, and pads.
Your lush indoor garden, like you, could do with a shower on an oven-like day – but occasional and moderate, otherwise you’ll spur the growth of fungi! So, set up a timer or a humidistat controlling the frequency of spraying and the humidity to work hand in hand with the misting system and your greenhouse will be right as rain!
Finally, there’s also an option of radiant earth cooling that involves installing subterranean pipes which carry cold water with the purpose of cooling down the soil.
Airflow is important both as a cooling method and as a way of refreshing the stale atmosphere within the glasshouse. For this reason, roof and side vents in addition to circulating and exhaust fans are a must!
The thing is that as the air warms up, it rises and should be allowed to exit the greenhouse through the roof making space for the cool one entering the structure through the sides. Opening doors or installing screen ones can additionally boost ventilation.
In case you don’t have the latter, remember to hook up some netting to keep wildlife out, yet letting pollinators in!
Apart from hand-operated vents, there are automatic ones opening and closing thanks to the wax cylinders which expand and contract depending on the temperature and, lastly, the costly electronic ones. If you’re going by the book, keep in mind that the size of roof vents should at least equal 20% of the floor area!
Undersoil fans are another alternative. They draw hot air from the greenhouse making it pass through the pipes buried one foot in the soil where its temperature reduces up to 10 degrees!
Shade Your Greenhouse
This is a successful method of combating high temperatures but it can be tricky due to plants’ need for light. Hence, attaining a balance between blocking the excessive heat and ensuring that enough sunlight is coming through is of paramount importance!
Shade paint is one shading technique that is both productive and practical because the paint is washable so it can be removed in autumn when it’s no longer needed. Check this one out! On the other hand, this option is not adequate for greenhouses made from unpainted timber.
External or internal blinds, shade cloth as well as mesh or netting can be a great heat-blocker lowering the temperature up to 10 degrees! My advice is that you place these outside for them to sieve the light before it even reaches the glass walls.
On the downside, if positioned thoughtlessly, they can obstruct the airflow through the vents and you’ll end up running around in circles!
Furthermore, when choosing the shade cloth, it’s recommended that you opt for a bright color (preferably white or silver) because dark ones can attract even more heat rendering all the effort vain.
When it comes to the percentage of shading, stick to the happy medium of 50% because you don’t want your plants to be deprived of light!
But be reminded that how much shade your greenhouse needs also depends on its design, the climate and the plants themselves.
Regarding positioning, hanging them on the south side will protect the vegetation from the sunlight during midday but won’t get in its way in the early morning and late afternoon!
Here’s an idea…
The inside temperature considerably depends on the glazing of your glasshouse, viz., if you have several layers, the warm air will hold back between them and won’t be able to escape at night or enter the structure during hot daytime.
Pondering for a while how to create the same effect in the most affordable way possible, I was looking at a sheet of bubble wrap my husband was tearing off his new mug when it hit me! So I garnered all the leftover bubble wrap we had at home, and headed to the store to purchase some more. The next day, my greenhouse was all wrapped up, tucked like a baby! And it actually works! Go figure!
1. How much sunlight does a greenhouse need?
First and foremost, tend to locate your greenhouse on the southeast side of your piece of land so that the amount of sunlight in which it bathes is on its maximum, particularly in the morning and during wintertime. Secondly, consider orienting it north-south to optimize photosynthesis by avoiding too much shade existent in the west-east oriented ones.
Generally speaking, every greenhouse requires a minimum of 6 hours of direct sunlight daily, otherwise, you’ll need to implement artificial lighting. However, each plant of a certain variety and in a certain development stage has different needs. For instance, young plants need less light but as the vegetative phase ends and the number of leaves increase, so does their craving for it.
2. What humidity should my greenhouse be?
Again, the perfect humidity differs from plant to plant but it’s an undeniable fact that too much of it will stimulate the growth of fungi. For that reason, keep it in the 50-70% range. So that you could keep an eye on it at all times and take steps accordingly, I full-heartedly recommend you install the aforementioned humidistat!
Now that you’ve realized that tending a greenhouse isn’t mission impossible even during the canicular days in an arid climate – dive in! Although some more sophisticated methods can be dough-eating, there are others which are economical, and, eventually, those which cost solely a tad of responsibility and resourcefulness!
Yet, the key factor is actually the relationship you nurture with your plants. Caring for a greenhouse is practically the same as looking after a child. For them to thrive, you have to be heedful of their needs, try hard to recognize and satisfy the latter and show empathy! They will love you back!
Don’t hesitate to drop a comment below and add any tip related to the topic! Your experiences on how to shade your greenhouse are always welcome!