Light is necessary for plants, but what type of light is best for your plants?
In this guide, we will help you find the answer to questions and doubts regarding the type of light you should choose for your garden.
Both the grow light and sunlight help plants produce food. However, the real comparison of grow light vs sunlight is in terms of control, expense, location, and power consumption, etc.
You can have an easy understanding of the difference between the two from this table. However, I would suggest you have a deep insight into all the aspects and effects of both lights before making up your mind about using any.
Plant bodies are living systems that react differently to different types of light. The reason behind this lies in varying factors of light like intensity, duration, color, etc.
How Plants Use Sunlight?
Plants produce food in a process called photosynthesis. In this process, water and oxygen convert into glucose and carbon dioxide.
The presence of sunlight is necessary to carry out this process because the energy from photons is used to split the hydrogen and oxygen from water to synthesize carbohydrates, or simply food.
Plants contain different pigments in their leaves that specialize in absorbing different wavelengths of light.
Differently colored lights have different wavelengths, which collectively appear as white light or sunlight. However, plants’ main light-absorbing pigments, chlorophyll a and b absorb the red and blue lights most effectively.
How Different Colored Lights Affect Plants Differently?
Pick up a prism and place it in sunlight, and you’ll see that the seemingly white light actually consists of 7 colors.
In this broad spectrum of 7 colors, each wavelength has its own energy levels that induce different changes when it falls on plant leaves. But the sunlight cannot be modified to give the light of a specific color.
However, the grow lights can be designed to impart the light of desired wavelength and color. Though they can completely mimic the sunlight too, most are designed to give the blue, red, or a mixture of both, as these trigger the most useful responses in the plant.
Despite that the complete range of white light spectrum plays part in the development of the plant, it is only blue and red light that plays the most important role.
Effect of Blue Light on Plant
Blue light, due to its lesser wavelength and higher frequency, is the most intense light in terms of energy. This high-energy light, although slightly decreases photosynthesis, highly increases vegetative growth, leading to the increased biomass of the plant.
However, growth resulting from blue light has a short internodal distance, and hence it is mostly lateral growth, suppressing an increase in length.
Effect of Red Light on Plant
Red light contains energy levels slightly lesser than that of blue light. This results in higher levels of photosynthesis. Increased photosynthesis increases the plant’s metabolism, and its ability to bloom flowers.
Though the red radiance might give the danger zone vibes, the enhanced flower blooming will fill your garden area with beautiful fragrance of flowers. The growth resulting from the red light gives high internodal length and hence contributes to the increased plant height.
How Grow Light is Alternative to Sunlight
Grow light is an artificial alternative to sunlight. As the name suggests, growth light is used to grow the plant by inducing similar changes in it as sunlight. The advantage that growth light has over sunlight is greater control and customization.
We cannot modify sunlight to impart light of specific wavelengths to maximize productivity. But we sure can modify the growth lights to give wavelengths of blue and red color only. It triggers enhanced vegetation and blooming of flowers aka fruiting.
Benefits and Limitations of the Grow light and Sunlight
While sunlight is friendly to beginner plant growers, the grow light gives more control to the experienced. Likewise, there are benefits and limitations of both, for people with different requirements and types of plants. The following table concisely explains the comparative effects of grow light vs sunlight on plants.
| Sunlight | Grow Light |
|---|---|
| Projects all 7 spectral colors, irrespective of whether plants need them or not. | Projects only the most effective spectral colors to the plants. |
| Cannot grow foreign plants in the local climate. | Can alter the conditions to grow foreign plants in the local climate. |
| Can only grow plants in their season. | Can grow any plant at any time of the year. |
| Produces plants of natural size and nutrient content. | It can produce enlarged fruits and vegetables by prolonging the duration of light. |
| You cannot directly lower or increase its intensity in any way. | You can set its intensity as per your requirements. |
| Produces plants of natural size and nutrient content. | Produces plants of natural size and nutrient content. |
| Plants grow and flowers bloom at their set time. | Plant flowering and fruiting time can be reduced by increasing the intensity and duration of light. |
| No further types or variants. | A lot of types and variants that need in-depth understanding before buying |
In a nutshell, it won’t be wrong to say that grow light is a better option for those who want greater control over their garden. However, both sunlight and growth light have their advantages and disadvantages over each other.
Therefore, giving an objective answer to whether you should place your plants under grow light or sunlight is not possible. The only person who can understand the individual needs and conditions of your plants is you yourself. All you need is to understand the factors that compare the two sources of light.
Factors to Note while deciding Grow light vs sunlight
Here is the list of factors that you must see around your house, and it’s surrounding to judge for yourself whether you need a grow light or sunlight.
Location
Not all houses receive the same amount of natural light. Moreover, the windows in closed homes are not always designed to receive sunlight for the complete duration that aligns with the biological clock of plants.
Under such conditions, the natural cycle of indoor plants’ growth, flowering, and fruiting will disrupt. They will still make a good decoration, but won’t fulfill their purpose of being fruitful.
This situation can be coped with by placing artificial lights on the plants and lit them for the same duration as natural light. Grow lights can even be used in grow tents or simply in the garden. This will prompt the plant to flower and fruit at its photoperiodically natural time, or even quicker.
Control
There is nothing you can control or change in the sunlight; it is what it is. You do not have a say in weather too; the rainy season can last for far more days than it did last year. It can cover the sun for weeks and ruin your set schedule and expected yield. This might be just an annoying situation for hobbyist growers, but is a nightmare for professional food growers.
The solution to this is by having grow lights for your plants. There is nothing you cannot change in the grow light; it is what you want it to be.
Climate
The availability of sunlight is not alike in all regions. Some might not receive it most of the year, and some might receive it much more than needed. The local vegetation of any area is adapted to these anomalous conditions.
However, if you want to grow foreign varieties of plants that require longer exposure to light, then you need grow lights.
With the greater control that comes with the grow lights, you can make your artificial lights mimic the duration of natural lights.
Temperature
Limited by the climatic conditions, you can only grow seasonal vegetables under the sunlight. However, with grow light you can decide what season it will be for your garden. Different grow lights provide different temperature, depending on their intensity.
By increasing the temperature, you can grow summer fruits in winter; and by lowering the temperature, you can grow summer fruits in winter. Such liberties are not available when using sunlight.
Though optimum temperature changes from plant to plant, the general range in which the indoor plants grow the best is 60 – 70 degrees F in the day, and 70 – 80 degrees F during the night.
Expense
If you want to keep gardening “just” a hobby that is not too heavy on your pocket, then sunlight is the way to go, as this is totally free. However, if you are willing to invest in this hobby that might return even more in the future, then grow lights do have benefits that sunlight lacks.
Even if you want to have economic benefit from this hobby, and lack the money to invest any, then starting with sunlight is fine. Once you get the experience of growing vegetables outdoors, then you can buy grow lights when it is economically viable for you.
The cheapest fluorescent grow light costs at least $150, and as requirements of intensity, footprint, and quality increase, so does the price.
Power
Unlike the sunlight, which does not need any input, the grow lights need constant power to keep them lit. So, if you live in an area with frequent power outages, then you will need a power backup. Grow lights can consume 10 Watts to more than 200 Watts power hour.
With power, expenses would also increase with the electricity bill or battery cost. If you use solar power, then the initial investment would still be high. So, check your budget before venturing into the lights’ domain for your gardening.
Duration
The biological clock, which regulates the mechanisms of the plant, is controlled by the duration of light; this is called photoperiodism. Through sunlight, plants get light at set times of sunrise and sunset. This limits our control of getting desired outcomes.
With grow lights, we can expose the plant to light as per our set time. Increasing the exposure duration can produce enlarged vegetative parts in case of vegetable plants, or can give quick fruiting in case of fruit plants.
The average time for an indoor grow light is 14–18 hours. It is matched with the natural sunlight times, unless there are some changes you want to see in the fruiting or vegetation.
Intensity
The intensity of light affects the shape of leaves, their chlorophyll concentration i.e. color, and also the stem length. Darker lights make the plants suitable to be indoors; by giving them shorter stem lengths, high chlorophyll concentration, and proper leaf shapes.
Sunlight gives constant intensity, not allowing us to get desired traits. But with grow light, we can grow our plants as we like by exposing them to the light of specific intensity.
Intensity is directly related to the wattage – power input – of the grow lights. Average LED light is given wattage of 15 Watts to cover a plant area of 1 square foot.
Keeping these points in mind, you can judge better for yourself whether sunlight would be better for you or grow lights.
Though most grow lights can do all the work alone, it does not necessarily need to be “grow light VS sunlight”; you can use the two together. Giving the plant both sunlight and grow light has also been proven as a good strategy for plant growth. Having understood all the factors that differ in sunlight and growth, all that remains to do is growing your seeds. So, get up, and start growing your favorite plants under the best light that they deserve.