Why is light important?Food and water are the two most basic and irreplaceable necessities for the sustenance of life – be it humans, animals, birds, or plants. For plants, water performs more functions than just hydration and light is the only source of food and they need plenty of it. For a healthy garden, the right kind of light plays a very important role – too much or too little and it starts to show in the shape of the plants, the size of the blooms, and also the colour of the leaves.
To understand how plants convert light into food, we will have to revisit the science we learned in school and take a look at photosynthesis. By definition, photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. The plant cell organelles called chloroplasts (they contain the pigment chlorophyll) trap light energy, this energy then stimulates a series of metabolic processes through which water (from the soil) and carbon-dioxide (from the air) undergo a chemical reaction to give oxygen (released into the air) and sugar (plant food).
6CO2 + 6H2O → C6H12O6 + 6O2
The sugar molecules plant food and are responsible for all plant growth from an increase in plant size, fruiting, and flowering, to immunity. So more, light means more plant food and more energy and that directly translates to healthier plants.
What happens to plants when the light is not right?Most of us gardeners miss the signs of low light that our plants give us and start damage control assuming something else is wrong, while all that was needed was just a change in placement of the plant.
Too much lightToo much light has its own issues and the following are some of the symptoms of too much light:
- Light is accompanied by heat and causes leaf burn (brown patches)
- Too much light also causes bleaching of leaves (loss of chlorophyll) that causes lightening of leaf colour and eventual reduction in the rate of photosynthesis and decline in plant health
- Leaves lose too much water (perspiration) to maintain the correct body temperature. If not monitored the plant can die of dehydration.
Too little light
Too little light is a deal-breaker and is much slower as far as the appearance of symptoms is concerned but if understood in time, it can be remedied easily.
- Light is plant food, so low light means almost a complete stop in plant growth – plant height, smaller leaves, no flowering, and thin stems
- Low light also leads to etiolation – the space between two leaves increases as the stem grows thinner and longer to reach towards the light
- Long spells in low light conditions cause plants to shed leaves and the oldest leaves also turn yellow and die.
- Loss of variegation. If the light is insufficient for your variegated plants, the plant will start producing more chlorophyll to make up for the low light. This is irreversible, although when placed in the correct light the new leaves will have variegations.
- One indirect consequence of low light is overwatering. Low light means lower rate of photosynthesis and less water is lost through leaves and a subsequent reduction in watering frequency Is needed, which we sometimes miss and overwater our plants.
Types of light – quality & quantityWith the advancement in technology and extensive studies on photosynthetic processes we have understood that light is just not light but so much more than that. Light for plants has too major components
QualityThe quality of light refers to its colour and type of light. By colour, I am not referring to the colours we see but the colours that the plants thrive in the most. The plants need the entire broad spectrum of light, the leaves appear green because they reflect green light and hence green colour light is useless for plants.
The red spectrum of light or warm light encourages chlorophyll production along with flowering and fruiting and stem growth. The blue light spectrum or the cool light is the most important spectrum and is key to intense photosynthesis leading to vegetative growth and a strong root system, it plays a key role during the early stages of plant growth (seedling phase). Only some parts of the green and yellow spectrum of light is used by the plants and most of it is reflected by the leaves.
QuantityThe quantity of light refers to both the intensity of light that reaches the leaves and the duration for which this light is available. Natural light from the sun has far greater intensity and the broadest spectrum compared to any artificial source of light. The more the number of photons (light particles) that hit the leaf surface, the higher the rate of photosynthesis. While fruiting plants and some foliage plants like begonias need light at full intensity for best growth. The correct intensity of light is essential for plants to convert air, water, and basic minerals into complex molecules found in fruits, rich colour pigments in flowers, fragrance, and seed formation.
While the sun does not give the same intensity of light from sunrise to sunset, fruiting plants need at least 8-10 hours of light through the day and flowering plants need at least 4-5 hours of sunlight.
Let’s take a look at different categories in which indoor and outdoor light can be classified into.
Indoor LightIndoor light is the sunlight you see within the confines of your home. It can be the light coming in from a window, through a curtain, on the patio, or just ambient light. It is important that we understand that indoor light is always 50 to 60% weaker than outdoor light because most of it reaches our homes after being reflected off nearby buildings, trees, and other such surfaces.
Bright direct lightWhat is bright direct light? The yellow sunlight that falls directly on any surface is called bright direct light. This kind of light is accompanied by heat. To make it simpler to understand, this is the light we pull out our umbrellas and caps for and slather on layers of sunscreen.
Bright indirect light
Medium indirect light
Artificial lightWhat is artificial light for plants? Artificial light for plants helps create the light spectrum in which plants thrive when natural light is not available. This situation can arrive if you live in a home that gets very little light either due to being in the shadow of nearby buildings or in areas that experience extremely cold dark winters. The artificial lights are easily available on eCommerce platform and are even easier to install, the only drawback is that plants need to be in close proximity of such lights for noticeable benefits.
Outdoor light is the light you get out on the streets or terrace when the sky is directly overhead and when you are not in the confines of four walls and a roof.
Different plants and their differing light needsAs mentioned several times in the preceding sections different plants need different quantities and qualities of light. While almost all ornamental plants live the happiest in bright indirect light, flowering plants need full sun for varying hours in the day.
The idea is to replicate the sun they get in their native growing conditions. For example, ferns and smaller tropical plants that grow on the forest floor need dappled or bright indirect light and tend to burn in full bright sunlight because they are soft leaves and soft stemmed and full sunlight rarely reaches the forest floor. On the other hand, succulents and herbs appreciate full sun because their native growing environments are such where they get full sun for most hours of the day.
While bright light plants generally can survive in lower light conditions, it’s not a permanent state. The effects of low light start manifesting with growth arrest and is generally followed by leaf drop and eventual death of the plant.
Choosing the right plant for the light in your homeIt is very important to understand the kind of light you home gets and further the intensity of light a particular spot gets where you want to place the plant. If all your major sources of natural light (doors and windows) are facing the north, flowering plants and succulents will be next to impossible in indoor spaces, but tropical and low light plants like ferns, philodendrons, ZZ, aglaonemas, and more will do well.
If your doors and windows are in the south, more or less every option is open to you for indoor spaces. But if you want to place plants in a south facing balcony then tropical plants, vines, and aglaonemas will burn, but you can substitute them with flowering plants, succulents and other sun loving plants.
Hacks to increase the light in your homeWe all love plants and if you have reached the last paragraph of this long piece then you certainly do. We want to have all kinds of plants in out garden – both indoor and outdoor, and if you, like me, are limited in your choices because your bedroom does not get the bright light your sitting room gets or vice versa, then I have some hacks for you.
- If you want to keep a bright light-loving plant like the Monstera or Fiddle Leaf Fig in a corner that does not get sufficient light, every Sunday (or any day) drag your plant out into the balcony or a spot indoors that gets the brightest light (indirect or direct) and let the plant soak it up before putting it back in the designated spot. But when placing in direct light then avoid the afternoon sun.
- Painting your walls white increases the reflected light inside your home making it easier for plants to absorb more light
- Using mirrors strategically also increases the amount of reflected light or helps redirect sunlight into the home helping plants thrive.
- Install a full spectrum of artificial light to help plants grow to their full potential.
I hope this helps you understand the important role light plays in plant health and growth. Reach out to us at Ugaoo if you have any more doubts and we will guide you through your gardening journey.