Does Temperature Influence Orchid Blooms?
Finding the correct temperature for growing your orchid is essential for it to bloom. You can water, apply humidity, provide light, and fertilize correctly, but if there's not a temperature fluctuation at night, most orchids will refuse to bloom.
Does temperature influence orchid growth? All orchids need at least a 10º to 15ºF degree temperature drop at night to bloom. This cooling off period at night removes the excess heat from their leaves. This aids in performing adequate gas exchange, since orchids perform their main “breathing” process at night.
"IMG_7076" by rsteele38 is licensed under CC BY-SA 2.0
During winter, do you run the heater during day and night, too?
If you grow your orchid in the same environment year-round, with no variation of temperature, the first signs you’ll see are of heat stress.
Heat stress occurs when the orchid shuts down its gas exchange (stomata) pores to preserve humidity. It does this because it’s too hot, and will lose humidity if stomata are opened.
Turn off the heater at night. Besides saving in energy costs, your orchids will appreciate the drop in temperature.
Orchids have temperature preferences, too. Not all orchids like to live in the same climate or habitat. When you bring an orchid indoors, you’ll need to recreate their primordial habitat within your home. Imagine if you place a cool-temperature orchid next to a warm-one and give both the same treatment.
One, or both, will have a hard time growing. That’s why it’s fundamental to understand the different types of orchids and how they react to each temperature.
Nighttime temperatures that are too low will produce blackened tips on the leaves. Flowers will wilt.
Tip: Don’t mistake these with the normal aging of leaves, which occur naturally. When leaves die off, the start to blacken at the tips. But temperatures that are out of control will also cause blackened leaf tips.
There are three distinct categories for temperatures: cool, intermediate, and warm-growing orchids.
- Cool orchids tolerate temperature of 50ºF (10ºC) during winter. During the summer, the maximum should be 75ºF (24ºF).
- Intermediate orchids prefer 55º to 86ºF (13º to 30º C).
- Warm growing orchids range from 64º to 90º F (18º to 32º C.)
Is temperature the only difference?
One misconception is that the orchids that thrive in these three distinct temperature categories are naturally from locations that have the same temperature. Even though this is an understandable mistake, it’s not the temperature that influences as much as the elevation.
Cool-growing orchids are found mostly in higher elevations. Elevation doesn’t necessarily mean in feet (or meters), either. Sometimes, you can observe cooler growing orchids higher up on trees, and not lower. But mostly, they grow in higher elevations compared to the other two categories.
by jay.37 is licensed under CC0 1.0
These orchids include:
In nature, the intermediate-temperature orchids can be found in an altitude that ranges from 1,000 to 3,000 feet. Of course, this does depend on how far away from the equator you are, too. The majority of the orchids that can be grown indoors come from the intermediate category.
by pirate_renee is licensed under CC BY-ND 2.0.
The last group, the warm-temperature orchids, coincide with lower elevation orchids. They are naturally gown closer to the tropics and the equator. Therefore, they thrive on high-light, direct sun, high humidity and...are extremely difficult to grow indoors. If you live in southern Florida or the Gulf States, you’ll have more success growing these outside.
Indoors, these warm-growing orchids are extremely difficult, near to impossible to grow, unless you want mold on your walls and indoor light system that recreates our sun.
The one exception is the most famous orchid, the Phalaenopsis.
It is a higher-temperature orchid, not to mistake it with a higher light orchid. These are two separate categories.
Vandas are also included in this category. The picture on the left is a vanda orchid.
"Kruidtuin, Leuven, Belgium"
by Jungle Garden is licensed under CC BY 2.0
What if an orchid gets exposed to higher or lower temperatures?
This open-ended question has a lot of what-ifs to answer. Usually, if the orchid is exposed to a colder temperature, like from the greenhouse to your home in the back seat of a car,
bud blast an occur. (Read this article
for more information on bud blast.) The leaves can wrinkle, curling up on themselves. These are reversible situations and can be avoided in the future.
If you purchase an intermediate-growing orchid, and constantly kept it a sub-par temperature, mold will start to grow
on the crown and leaves.
But if the orchid is exposed to year long exposure of temperatures that are sub-par, they probably won’t blossom. Smaller pseudobulbs
will grow compared to last years. Leaves can dry up and fall off prematurely
. Flowers wilt. The growing period will take longer, and new roots and flower spikes will take forever to appear. Insufficient lighting
is the number one reason orchids won’t bloom, but the second is too low of temperatures.
If you don't have one already, a thermometer with a humidity gauge is essential for orchid care. They are rather cheap, like the one I have (Affiliate Link)
cost around 12 US$.
If you observe the graph above, you might be thinking, “But my Cattleyas grow in 100ºF weather during summer.” When literature refers to orchid temperature, they always record the highs and lows as observed during the winter months.
Summer is not accounted for.
Why is this? During summer months, temperatures will naturally be higher, but won’t hinder growth if you’re a bit outside the natural preference zone. As long as you don’t overheat or provide too much sunlight, causing sun damage, there will not be much to notice.
It’s during winter that the temperature has more direct effect on the growth of an orchid, and can hinder blooming. This isn’t to say that if you have a cool-growing orchid and force it to grow in hotter conditions, it probably won’t blossom.
Temperature Fluctuations Night/Day and Seasonal
Not only do orchids need a fluctuation in temperature during the days/nights, they also need a distinction between seasons. You’ll see this more when you purchase winter blooming versus summer blooming orchids.
Seasonal distinctions are extremely important to orchids, as other houseplants, too. During winter, there will be a shortage of natural nutrient supply, so you’ll need to water less.
Fertilize less, too.
The days will be shorter and darker, so you can turn down your artificial lights to around 12-14 hours a day, instead of 14-16 hours.
"Green Orchid Bee (Euglossa dilemma)"
by bob in swamp is licensed under CC BY 2.0
There will be less pollinators in the environment to justify blooming.
This is crucial.
A flower only blooms to propagate its species, and if they attract a certain type of pollinator, that only comes in winter or summer, why waste the energy to bloom out of those seasons?
This is why each orchid species has a different blooming period: some bloom in summer, other spring, others winter… The upside is that you can have orchids in bloom year-round in your house if you choose the right ones to make your collection. Phalaenopsis bloom year round.
Think back to the natural habitat of the orchid. There aren’t such distinct summer/winter changes, in terms of temperature. Most subtropical and tropical orchids live in a constant temperature year-round, only fluctuating during the day and night.
During the day, no matter summer or winter, the orchid needs to be in a warm place. Indoor orchids do well because temperature fluctuate less and are easier to control.
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How to maintain temperatures
Let’s say you went to an orchid greenhouse and came home with a Cattleya and a Phalaenopsis. Knowing that these are in two separate groups (according to temperature), you’ll know that placing them side by side on the same shelf won’t be the best solution.
To have more success at growing orchids, you can set them up depending on their temperatures, each in a different corner of your house. Use the windows and natural sunlight, and group orchids together by their temperatures.
A good suggestion is keeping the cooler orchid in the bedroom, warmer orchids in the kitchen, and intermediate orchids in the living room. Of course, this is a wild suggestion, but you get the idea. Grouping them together provides humidity, but also is easier to control variant temperatures and lighting.
This way it is easiest to display your orchids without having a proper greenhouse, orchid room, or making your house transform into a live jungle.
Too much information to memorize?
Download this 1-page PDF
reference of what you learned on this article and other important information about artificial lights, which you can read here
If you are interested in the artificial lights that I use, you can see them here (Affiliate Link)
but read the article above first. My growing conditions are not the same as everyone else's.
This free download is for your enjoyment only.
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Now that you know how to care for your orchids according to their temperatures, drop us a comment below on anything that wasn't touched upon in the article or if you have a question or comment.
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