20 December, 2021 by
Lucija Johum

Growers today are mastering an amazing technology to get ahead of the horticultural curve: light deprivation!

A method for producing high quality, beautiful flowering plants, farmers and gardeners alike use it to manipulate light and darkness, making their flower crops available any time of year – and without any negative environmental impact.

How does this work? If you haven’t yet delved into the science behind flowering, it can seem a bit complicated – though it really isn’t when you get into it.

Long story short, light deprivation greenhouses utilize timed covering and uncovering mechanisms to simulate artificial darkness with a blackout fabric and system. 

For some species of flower, this creates the perfect conditions for blooming: allowing you to produce magnificent blooms, widen your production window, and boost both yields and profits!

Would a system like this be an excellent addition to your operation and your specific crop? Otherwise, what flowers should you choose for your new light dep system?

There’s a few ways to know, and a diverse list of choices. Let’s take a look!


The secret behind which plants are best for light deprivation? It comes down to a scientific term called photoperiodism.

Photoperiodism is the effect of day and nighttime lengths on living beings and their physiological functions. It affects both animals and plants, but is very influential on life in the botanical world – and particularly flowering times.

On the one hand, some flora are stimulated to flower under long daylengths and short nights. Or, the opposite might be the case: short daylengths and long nights encourage flowering in other species (though some aren’t influenced by daylength at all).

The very best plants for a blackout system? Those that prefer short daylength and long night conditions to flower. 

These are called short day plants, and you can make them flourish astronomically under light deprivation conditions!


Since short day plants make moves to flower on or after the equinox – when daylength starts to dip below 12 hours – light deprivation is perfect to make them also available at other times of year.

Otherwise, growers are very limited to when they can grow and harvest short day flowers, if you think about it!

Not so with sophisticated blackout systems. These encourage short day plants to produce beautiful, high quality flowers, even throughout spring, summer, or any time of year – and regardless of daylength.

It’s the ultimate method to extend nighttime and shorten daylength at your control.

So, which plants would be best for your setup?


While blackout systems have been used to promote flowering conditions for many decades and with many flowers, they have mostly surged to popularity at the same time that cannabis agriculture has in the recent decade.

In fact, this is because technology for light deprivation greenhouses is almost synonymous with the cannabis industry – though not exclusively so. 

Still, if you research light dep growing, you will find that commercial cannabis is the #1 crop most associated with the system, and not without reason. 

Naturally, cannabis is limited to flowering and harvest only in fall. These specialized greenhouses, however, allow them to flower and provide harvest any time of year.

With cannabis being such a high-priced commodity in this day and age, having the ability to literally double your production with these greenhouse systems is a huge appeal! 

What more, you can grow a more exceptional crop at the height of midsummer than in winter, due to the intensity of sunlight during that time.


Many types of aster respond to short daylength and long nights. The most notable species may be the New England aster, which can be seen blooming in the wild along roadsides in the fall.

However, domestic strains can be triggered to bloom at their best with fall light conditions, too! 

If you’re looking to sharpen your competitive edge in spring or summer for selling cut flowers, you can add a splash of color that other growers may not provide by growing asters with your blackout system – they’re another great short day flower option.


Christmas cactuses are lovable to hobby growers and houseplant lovers alike. With such a demand, they’re definitely worth it for commercial growers and florists to produce, too.

As their names reveal, these tropical plants from South America tend to bloom around Christmas – though some other similar breeds, such as the Thanksgiving cactus, bloom even earlier.

Can you make them bloom at any other time? You bet: with the help of a light deprivation greenhouse. Since they’re tropical, a hybrid light deprivation system with temperature and humidity controls could make year-round production even more successful.

According to the University of Illinois Extension, a nighttime length of 14 hours will do the trick, and this is entirely possible with a blackout system!

If you’re wanting to add a more exotic flavor to your flower business (or hobby), try your hand at cut Christmas cactus flowers for floral arrangements – or even potted plants ready to display fabulous flowers any time of year.


Relatives to asters, cosmos flowers will refuse to bloom until daylight lengths begin to shorten – something that only happens naturally after the fall equinox.

Not so with a light deprivation kit. 

As long as these flowers get all the care they need otherwise, with a blackout system they’d be happy to bloom whenever you like. You can also continuously deadhead them to keep flowers producing on, and on…and on!


Chrysanthemums are famous flowers, brilliantly blooming as the summer season winds to a close. 

This, too, is due to the shortening of daylight – a factor that tells mums: “it’s time to reproduce before winter comes!”

If you’ve ever tried growing mums yourself, you’ll notice how they get bushy and leafy during summer with so much daylight; but when the daylight recedes, they’re fonder of flowering instead.

However, if you’re wanting to introduce chrysanthemum flowers into a market during a time when they’re not usually available, a light dep greenhouse can help you achieve this. This can make them excellent options as retail potted plants or cut flower additions.


Ever wondered why poinsettias are so popular around Christmastime?

It’s because these holiday tropical flowers produce their large, leaf-like colorful blooms right up until this time, starting in autumn. And nothing beautifies the home more appropriately during the holidays!

As written by the Cooperative Extension of Michigan State University, hobby growers and houseplant owners of poinsettias are recommended to cover their plants at certain times of day, from October 1st until mid-December. This guarantees that these plants will show off those vibrant colors we all look forward to.

Allow them even the slightest bit of too much light, however, and you’ll miss out on the show!

If you choose to be a commercial grower, however, cultivating this yuletide flower could be amazingly successful with a blackout system. Combine this with a hybrid system, and you may be able to produce poinsettias at very unusual times when they’re scarcely available – even early spring.


A famously easy flower to grow, zinnias are great for beginning gardeners who want to get acquainted with sprouting their own cut flower garden.

Typically, these annuals are effortlessly planted from seed in spring. A month or two later, they are much obliged to flower any time after the summer solstice and well into the fall, after the equinox.

But what if that’s just too long a wait for a commercial grower? And what if you’d love to get zinnias to customers earlier as a cut flower in early spring?

You guessed it: a light deprivation greenhouse! A blackout system can help you get an early start on these annual blooms. 

Instead of waiting until the last frost to plant out seeds or transplants, you can nurture seedlings as early as mid-winter in your greenhouse, and get them blooming in spring – giving you a competitive edge over other flower-growers by making it available when others can’t.


Do any of these plants have you thinking about how you could expand your flower growing passion?

With a light deprivation greenhouse, you’ll work harmlessly in harmony with nature to bring beautiful blooms to markets that wouldn’t have been available otherwise!

Lucija Johum 20 December, 2021
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