Plants get their energy from specific nutrients and a certain amount of light. They both work in tandem to aid with consistent growth. One of the key nutrients required in plant development, magnesium, helps the plant to form chlorophyll.
Chlorophyll is a pigment that a plant uses to capture its energy from its light source (Sunlight for example). It does this by using a process called photosynthesis. This results in the light source helping the plant to grow.
Do hydroponics need sunlight as well?
To be honest, it is possible to grow certain plants without sunlight but most require a particular amount to undergo photosynthesis. However, when growing using hydroponics, sunlight isn’t required as long as it can be replaced with adequate artificial light.
Let’s have a look at how to make sure that your plants get the right amount of light from the right source within a hydroponic environment.
If you are wondering about how to replace sunlight for hydroponics: Do LED Lights Work For Hydroponics?
Table of Contents
Do Hydroponics Need Sunlight?
Regardless of the location of your hydroponic set up, the light produced naturally by the sun can always help but it isn’t a necessity. The light created by most artificial lamps on the other hand is designed in such a way that it replicates the sun.
They can be set up to run for specific time periods in the exact same way as a sun would. In fact, artificial lighting can be better in the way that it’s possible to set a timer for even longer hours than the sun naturally shines to promote even faster growth.
Keep in mind that plants also need darkness so they shouldn’t be blasted with 24 hours of light. So in short, hydroponics don’t need sunlight to grow, they just need the right type of light.
Is Hydroponics Without Sunlight Possible?
Hydroponics without sunlight is definitely possible. As previously mentioned, plants need the right type of light as well as the right amount of light to give them the best possible chance at sustainable growth.
Here’s the catch though, you can’t just use a conventional light bulb and expect results. Lights or lamps specifically designed for hydroponics generally offer certain ranges on the light spectrum. These ranges affect the different stages of a plant’s growth just as sunlight would.
Different colors within those ranges help with these particular stages. We’ll get into that very soon. This is what is meant by having the right type of light though. The sun has a built in light spectrum so it’s important that your system can replicate everything that the sun can offer to ensure a formidable yield!
Types of Grow Light
There are a few different options to choose from when it comes to growing lights. Choosing the right type of light for a specific setup is crucial to its success.
Furthermore, some light choices suit certain systems better than others. Each light type comes with their own benefits and drawbacks. Let’s have a look at the most popular and effective and see how they compare.
LED (Light Emitting Diode)
LED lights are fast becoming the top choice for all levels of growers. In the early days of LED development, they were considered as too expensive due to their upfront costs.
Whereas now, the improvement of LED technology has enabled them to become not only a lot more affordable but also, extremely durable as well as long lasting.
This in turn deems them extremely efficient. In fact, they have the highest life expectancy amongst the top choices, boasting a whopping 50,000 hours. LED lights produce less heat meaning they won’t burn the top of your plants.
Additionally, the light that it does produce is much more intense. As a result this light has the ability to pass through the top canopy of the plant. Consequently, the lower sections of the plants receive the same amount of distributed light. For this reason, LED lights are rated with high regard.
High-Intensity Discharge (HID)
HID lights are pretty much the OG when it comes to hydroponic lamps. They are those more elongated shaped globes that are screwed into a connection point. Additionally, the connecting piece is covered by metal ‘wings’ which help distribute heat and light.
This type of lighting produces a heat that is considerably more intense than most other types. So much so that the lamps must be set up with ample spacing between themselves and the plants. If they are placed too close, there is an increased risk that the plants will burn.
HID’s can be utilized with great success within both vegetative and flowering/fruiting stages. Due to the output of heat that these lamps produce, the downside is that they are more costly to run.
There are 2 different types of HID lights, Metal Halide (MH) and High-Pressure Sodium (HPS). They can both be used within the same setup but must be changed during the different stages of your plant’s life cycle.
- Metal Halide – Emits blue light (vegetive stage).
- High-Pressure Sodium – Emits yellow light (flowering/fruiting stages).
Fluorescent
Compact Fluorescent Lights (CFL) can be used as a last resort but the reality is that they are fast becoming obsolete due to LED technology. They were (and still are but only just) easily accessible.
This is because they were used as a common household globe. CFL’s are a great option when setting up your hydroponics in more confined spaces as they give off minimal heat. The light produced has enough intensity to be utilized for both vegetative and flowering stages.
| LED | HID | CFL | |
|---|---|---|---|
| Suited for | Dense foliage plants (bushy herbs) | Cereal, forage, citrus and C4 plants | Seedlings, clones, or small plants |
Lighting Requirements for Hydroponic
For a hydroponic system to be successful, it requires specific types of light. Furthermore, the light that is required needs to be of different colors within a specific spectrum which emulates the sun.
The right amount and type of light, coupled with optimal environmental conditions, ensures that the process of photosynthesis can occur.
Photosynthesis is a means in which plants produce their own energy source (food) that enables them to grow and develop successfully. In order for this process to be able to occur, plants require sunlight, carbon dioxide, water and chlorophyll.
All plants have chlorophyll which is a pigment and is also what gives them their green color. Plants absorb water and minerals through their roots as well as carbon dioxide via their leaves.
These 3 elements are mixed together (called ‘raw sap’) and are added to the chlorophyll. As the sunlight reaches these now 4 elements. They are turned into elaborated sap.
Consequently, the sap is absorbed by the whole plant from head to toe as used as the plant’s food source. This is why light is so important, it brings all of the photosynthesis process together.
Let’s have a look at characteristics of light to ensure that the requirements can be met.
Wavelength of light
A wavelength of light is the definitive distance that can be measured between the two successive crests (highpoints) or troughs (lowpoints) of the light wave. Or in other words, two back-to-back waves.
Different wavelengths of light emit particular amounts of energy depending where they are on the color spectrum.
Different stages of growth require specific wavelengths of light to obtain optimal growing conditions. These wavelengths of light can best be described using the color spectrum.
Color spectrum
Colors as we see them are just electromagnetic radiations with different wavelengths of light. We only see what is called ‘visible light’ These colors are measured and shown on a spectrum called the visible spectrum.
By the same token, plants use these wavelengths of light to enable certain stages of their growth cycle to occur. These wavelengths can be achieved by utilizing different colored lamps or lamps with full spectrum characteristics. Different wavelengths are more suited to different stages.
For example:
- Violet/Blue light is more used for vegetative stage (400nm-500nm)
- Red/Far Red is more used for flowering period (620nm-780nm)
It’s worth noting that some light is not visible to the human eye like UV (180nm-400nm) and Infrared(700nn-1mm). These are on the far ends of either side of the visible spectrum
The wavelength of the visible spectrum of light is as follows:
| Color | Wavelength | Frequency |
| Violet (shortest wavelength) | 380-450 nm | 668-789 THz |
| Blue | 450-495 nm | 606-668 THz |
| Green | 495-570 nm | 526-606 THz |
| Yellow | 570-590 nm | 508-526 THz |
| Orange | 590-620 nm | 484-508 THz |
| Red (longest wavelength) | 620-750 nm | 400-484 THz |
How much wattage per square foot?
This can be answered by figuring out how much area that you are looking to light. The first step to this is working out how many square feet you aim to light up in the growing area. This can be achieved by measuring your growth area.
For example 3m X 3m
The next step will require you to know what you are growing. Different plants demand more or less light. Lower light plants like lettuce or leafy herbs call for 25-30 watts per square foot. Higher light plants like tomatoes for example crave more along the lines of 40 watts per square foot. Let’s use tomatoes as an example and do some simple math to retrieve a definitive answer.
So we had:
3m X 3m = 9 sq ft (W x D = sq. ft)
Then we X watts of tomatoes = desired amount of watts
40 X 9 = 360 Watts
We can round that off to 400 Watts as that is what is purchasable or at least more easily available.
Advantages and Disadvantages of Sunlight for Hydroponics
Having some added sunlight to your hydroponic setup can have its benefits as well as drawbacks, lets have look into them:
Advantages
Money Saving
If your hydroponic system is set up in an area where you have the luxury of some extra rays from the sun, this can help keep your budget down in the long term. The more sun that you can utilize, the less you will need to use your lamps, this in turn can minimize your electricity costs.
You may be able to set up your system in a greenhouse outdoors or in a very well lit room indoors. Of course, you will need the lamps to assist where the sun may lack. Eg: the sun may only be able to produce light for half the time.
Space Saving
If you can take advantage of the sun then it is possible that you won’t need as many lamps within your system which can help save on space overall. You may have required a specific amount of wattage without the sun’s help but if it can assist then you may need less wattage. Less wattage can mean less lamps.
Disadvantages
Hydroponic setup placement
Due to the fact that the sun does the same thing every day, the location of your hydroponic system can either be a help or a hindrance. It’s a big decision to make if you are planning on using the sun for some extra help.
You can be a little bit limited depending on what your location is like. Eg: You may not have any light coming in on the side of your property that the sun shines. That’s not exactly the sun’s fault but it’s something to consider nonetheless.
Reliability
Relying on the sun alone is an issue that any knowledgeable grower understands. This is because as we know, the sun doesn’t shine the same way every day. It can be dark and cloudy for periods also.
Advantages and Disadvantages of Using Grow Light
We have looked at the pros and cons of sunlight and its ability to work alongside a hydroponic system. Now it’s time to check out how a grow light can go for or against a hydroponic setup.
Advantages
Sun Replication
The beauty of using grow lights to assist the hydroponic process is the ability they have to replicate the sun. They can cover the full spectrum and pretty much deem the sun unnecessary.
They can also be set to specific times so they are spot on with the sun’s time range. Depending on the type of lamp, heat and intensity are also other characteristics that can be tinkered with to match the almighty day time sky orb!
Year Round Yield
Grow lights enable a consistent growth of a variety of different plants all year round. Adding to that, this can be undertaken regardless of climate. Whether indoor or outdoor (undercover) you can be assured that growth can be achieved.
The Perfect Plant
Lights and heat are only a couple of elements required for successful growing. Knowing that these can be adjusted can help in the quest to nurture the perfect plant. Once you get the formula right, all that is required is to rinse and repeat for continued success.
Disadvantages
Cost
Planning out your system before you begin is vital to keeping the budget down. This includes your energy bill, and supplies.
Upfront costs and excess usage of lamps can become expensive if you’re not serious about mastering how to grow. Most growers do what they do to either become self-sufficient or even sell their produce for a little extra income.
Risk Of Light Burn
Careful consideration must be made when initializing the setup of your system. If the lamps are installed too close to the plants then you run the risk of causing light burn. This can also occur if the wrong types of lamps are used for a specific stage of growth.
Frequently Asked Questions (FAQs)
01. Do purple LED lights help plants grow?
Purple lights are technically just red and blue diodes within the LED which when mixed together, emit the purple color. These LED lights optimize both red and blue on the light spectrum within the LED.
So technically, yes, they are better as they have the exact combination of light required for specific states or stages of a plant’s growth cycle.
02. Do seedlings need red or blue light?
The optimal color for seed germination, root growth, and bulb development is red. The red color helps plants flower and produce fruit. Although, if the plants are positioned below a thick canopy of leaves, blue light may be needed as well. Of course, that is if you have a mix of different plants while in this stage.
03. How much heat do grow lights produce?
The amount of heat through its fuels or energy sources is measured in BTU’s. To work out the amount of heat pumped out by a specific globe/lamp/light, you take the amount of Watts X 3.41. 1 Watt of power = 3.41 BTU. So an LED with 500 W (550 W with the loss of drive) generates around 1.877 BTU per hour of heat.
04. How many watts do you need for hydroponics?
The required amount of wattage required for a hydroponic system will vary. It depends on the size of your grow area and the type of plant that you aim to grow. If your area is 5m X 5m and you want to grow small herbs that need 25-30 watts per square foot then the amount of watts would look something like this:
5m X 5m = 25 sq. ft
25-30 X 25 = 625 – 750 watts per square foot
05. How much light do I need for hydroponics?
As a general rule of thumb, you should set your hydroponic system up so it simulates 14-16 hours of sunlight per day. Some plants can even require as much as 18 hours.
Furthermore, you should allow 10-12 hours of darkness for annuals per day. Plants need the chance to rest and metabolize just as much as humans and animals do.
Conclusion
Growing your plants using a hydroponic system is a great way to cultivate a consistent and extremely sustainable source of fresh produce. Moreover, it doesn’t need too much space, it’s low maintenance and produces much higher yields. The beauty of it is that you are in total control of pretty much every facet.
Once you get the hang of how the system works, it’s like riding a bike. There are a few minor queries that are a little unclear though. One of them being, do hydroponics need sunlight? It would seem that there is a simple reply to this question but it’s definitely one that requires a more in depth answer.
Let’s dive in and get a deeper understanding of the importance of sunlight or more so light, within a hydroponic setup.
