Growing Plumeria Indoors
with All the Colors of the Rainbow

Growing plumeria indoors is not the best idea, you need to provide special lighting, watering, and misting, and you will not get as good growth or flower colors or production as outdoors. Mabe this article will help you learn about lighting and how important it is.

The impact that light has on the human eye is different than the effect it has on your plants. Plumeria takes in light to use in the photosynthesis process to convert energy into sugars to consume as food. Different colors of the light spectrum have varying impacts on the quality of your plants, the rate at which they grow, and when they fruit or flower. We had the chance to pick the brain of  John G from Sunlight Supply, that was nice enough to share his knowledge and expertise. Come ride the colors of the rainbow with us and learn more about how light spectrums and light exposure affect your plumeria.

Eye Spy With My Little Eye

To better understand what you are offering your plumeria when flipping that light switch, let’s break down some industry info. The light spectrum is measured in nanometers (Nm)- that’s one billionth of a meter. Typically, when evaluating the light spectrum you look at the realm of 380 Nm to 780 Nm. We call this the lumen scale.

Well, you only “see” the scale of 400-700 nm with the human eye. That’s why in the industry we tend to say that “lumens are for humans.”

Somewhere Over the Rainbow

The 400-700 nm scale is what we know as primary (red, blue, and yellow) and secondary colors (orange, green, indigo, and violet). Plumeria has the ability to see further into the ultraviolet (<390 nm)  and infrared (700+ nm)- the furthest ends of either side of the light spectrum. However, plumeria does not benefit from these extreme ends of the spectrum.

Plumeria experience infrared and ultraviolet in the same capacity that humans do. Infrared is perceived as warmth (1) and does not aid in any vitamin or chemical processes and ultraviolet (UV) rays will prohibit growth and can actually burn and kill the plant, much like overexposure can burn skin.

Mimicking the Great Outdoors

It is a true artist of a grower that can truly mimic the sun. When growing indoors, you are constantly attempting to recreate environmental factors within an enclosed space. From your ventilation system to your lighting, you are trying to mimic both the wind and the sun to trick your plants into believing they are in their natural habitat. Part of mimicking the free offerings of nature is attempting to recreate the seasons for your plants so they know when to flower and/or fruit.

Plumeria responds to the different colors of light due to their ability to trigger different stages of the growth cycle.  

Plumeria’s photoreceptors and hormones are affected when exposed to certain spectrums in different intensities. The segment of the light spectrum that plumeria is responsive to is called the photosynthetic active radiation (PAR). PAR accounts for the 400-700 nanometer wavelengths that plants see and utilize for growth and development. When playing with the spectrum that you apply to your plumerias, it allows you to forgo the use of plant growth regulators that can have potential weird side effects on your plumeria. By discovering the desired balance of spectrum and an ideal number of “daylight” hours your plumeria prefers, you can manage growth naturally (the preferred growing method).

Green Doesn’t Mean Grow

Your plumeria appears green because it is the color of light they do not absorb and actually reflect. Plants have no use for the color green on the light spectrum and as a result, is the color we perceive with our eyes when looking at them. Plants also appear green due to the chloroplasts in the leaves of your plants that produce chlorophyll and are the energy production system of the plumeria.

Red Light District

Plants have a photoreceptor that is blue-green in color and called a phytochrome. The sole job of phytochrome is to absorb red light. The absorption of red light will increase your plumeria’s production of a hormone called metropolis.  This hormone prevents the degradation of chlorophyll in the foliage of your plumeria and is what allows a plant to stay green during the spring and summer months. The more chlorophyll that your plants have, the higher ability they have to process more energy and promote their own growth. Red light also helps your plants to determine when to flower and affects seed formation.

The secondary colors on the red side of the spectrum (yellow and orange) have a similar, but less intense, effect as a red light would.

Due to the effect that red light has on triggering the flowering phase of your plumeria you should avoid exposing your plants to red light during their dark period.  This means not opening the door to your grow space for any reason during their dormant hours or having any other lights within your grow space that may affect them (i.e. power cord power buttons, automated controller LED lights). We recommend covering any lights with black electrical tape to minimize exposure to unintentional light sources.  It may seem melodramatic but, just like your emo best friend, your plumeria is sensitive little souls. The exposure can extend the vertical growth period and put off the flowering phase. 

Blue Hue

Just as with the exposure to red light, plants also have a photoreceptor that uses blue, indigo, and ultraviolet light. The blue photoreceptor is called a cryptochrome. In the presence of elevated blue light, which is typically emitted more by the sun in the fall season, a plant will slow its vertical growth. This is due to the fact that blue light slows down the production of the hormone called auxin. Auxin is responsible for both root development and vertical growth. When the production of this hormone slows, plants begin to branch out laterally, growing more bushier as opposed to taller.

Plumeria also uses blue light to determine how much or how little to open their stoma (the pores of the plant responsible for taking in CO2 and emitting water and oxygen). The plumeria reads the amount of blue light present and will use this information to either increase growth or to slow development and go into the flowering phase.

The far side of the blue spectrum enters into the ultraviolet territory and can be both beneficial and harmful for your plumeria. Just like the UV effect on your skin, it can cause DNA and membrane damage. However, UV can also increase the production of anthocyanin, which can give your plumeria a purple hue but also help your plants naturally defend themselves against lethal microorganisms. It is a delicate balance. 

Light My Way

There are many different light methods that have been used in the growing industry. More recently, the norm has shifted towards the use of mixed spectrum lights that are composed of both red and blue spectrums, created to mimic the sun. Daylight as we call it is full spectrum.  The only downfall to daylight is that in some cases its can be too much light. You will notice that many times at the brightest time of the day plumeria will drop their leaves and basically shut down photosynthesis. You can see this in garden centers when the plant description tells you how much exposure the plant really likes.

This balance is best set at a 5:1 red to blue light ratio but there are many growers that still use plant or light transfer methods. By this we mean, either changing out your bulbs from a primarily red to blue light when ready to move into the flowering stage in smaller operations. For larger operations, it may be easier to move your plumeria into a “finishing room” with a higher blue spectrum lighting.

You can create your own custom light spectrums by being intentional when combining and choosing your grow lights. When customizing your lighting spectrum, we are big fans of Hortilux bulbs. You can select lights, such as the Hortilux family, to fill your four lamps or eight lamp fixture to create a blue specific formula to use during your veg cycle. You can also select from their FLOWER line to let your flowering/fruiting plants reap the rewards. If you are looking to create a mixed spectrum fixture, you can combine lamps that will help to stimulate an outdoor growing environment and allow you to avoid any exchange or further thoughts to your grow lights than routine maintenance. 

The More You Know, The Better You Grow!

Step Into the Light

Your lighting system is an art form to perfect as an indoor gardener. Developing a system for your plumeria that gets you the most return on investment takes time and experimentation. To help get you there a bit faster there are a few pro-tips that can help you develop your lighting system:

  • Give your plants a 24-36 hour darkness treatment to speed up your plant’s transition into bloom
  • Stick to a rigid 12-12 lighting schedule with no interruptions once your plants have entered their flowering cycle
  • Use a light timer to keep your plants on a consistent light schedule and know that schedule so you don’t disturb them when they are sleeping
  • Even brief flashes of light exposure during your plants’ dormant hours can cause damage to your plant’s cycle and can take upwards of a month to readjust

Lighting is an essential element to creating a quality growing environment. By staying informed with our fresh industry information, the more you will come to know how to improve your grow area! Keep your eyes peeled for more information about how to choose the right lighting for your growth and how to use it on our blog page.

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