What Types Of Growing Lights Should I Use For Indoor Farming?

Indoor cultivation offers many advantages. The biggest advantages are obvious: pests in the garden cannot reach your plants and you have complete control over the weather.

However, if you are not lucky enough to have a tanning bed or greenhouse in your home, providing enough light for your plants is likely an obstacle (except for shade-tolerant houseplants). South-facing windows can provide enough light for a tray or two of seedlings. However, if you want to grow vegetables or other sun-loving plants to maturity, you will need to grow light.

Indoor lighting in most households contributes little to photosynthesis. Conventional light bulbs do not have the correct spectrum or intensity to move the sun. Household fluorescent lights can produce effective grow lights, but only if they’re just inches from the foliage and left on for 16 hours a day – not ideal.

What Is Grow Lights?

In its simplest definition, a grow light is an artificial light source, usually, an electric light, designed to stimulate plant growth by emitting an electromagnetic spectrum perfect for photosynthesis. Such lamps are often used in applications where there is a lack of natural light or where additional light is required. For example, let’s say that grow lights can be used during the winter months to provide extra hours of light for plant growth. It also aids in growing fruits and vegetables indoors.

On large covered farms, grow lights can completely replace direct sunlight. However, grow lights don’t always have to closely mimic sunlight. They can outperform sunlight in many applications.

Warm vs Cool: Understanding the Color Spectrum in Grow Lights

When you shop for grow lights, you will find that they are labeled with numbers like 2700K or 4000K. This refers to their relative warmth or coolness in the color spectrum – the higher the number, the cooler the light. Foliage growth is generally best around 6500K, although many plants require a warmer light period of around 3000K to produce flowers and thus fruit.

In other words, if your goal is to simply produce seedlings, leafy green vegetables, or root crops, you only need higher spectrum onions. If you want to grow flowers, marijuana, or any fruiting plant (cucumbers, tomatoes, peppers, lemons, etc.) you also need low-spectrum onions. You can supply some types of bulbs in full-spectrum form, but they simplify things.

Types Of Grow Lights

There is no one type of grow light to choose from. They are all useful and have their pros and cons. Let’s dive into each of them.

High-intensity discharge (HID)

HID is a type of light bulb that conducts electricity through a gas-filled tube.

HID remains a popular choice for beginners, be it HPS or MH, due to its low setup costs.

Three types of HID grow lights are used in indoor growing: high-pressure sodium (HPS), metal halide (MH), and ceramic metal halide CMH


HPS emits strong light at the red and orange ends of the light spectrum, which is better suited for the flowering phase of plants.


MH is often used in the vegetative phase of plants because it provides a larger blue light area of ​​the spectrum


Ceramic metal halide, also known as Light Emitting Ceramic (LEC), is used as ceramic HPS arc tubes. CMH is likely a combination of HPS and MH, so CMH has a wider light spectrum making it a great single light solution.

While CMH is more efficient than regular MH bulbs, there are no more lights in the red spectrum than HPS. As a result, CMH cannot beat HPS when it comes to the flowering phase of plant growth.

And it is still not proven that using a single broader spectrum of PAR light is a more efficient solution in terms of cost, crop yield, and convenience than a combination of the two.

HID Grow Light Tips

You can use three types of bulbs (HPS MH and CMH) for a full growth phase from start to harvest, but this is not highly recommended. Usually, start with MH or CMH during the vegetative phase. Then switch to HPS during the flowering period.

That means that if you want to use HIDs you have to buy an MH and an HPS lamp type separately, as the HP igniter does not fit MH and vice versa.

However, you can consider a conversion lamp that allows you to run HPS lamps on an MH ballast or an MH lamp on an HPS ballast.


  • Relatively cheap
  • Stable, high-quality yields have proven themselves in the past.
  • User-friendly and consistent models for all suppliers. Unlike LEDs, you have to find out which spectrum, which positioning, and which types of models are suitable for plants.


  • Ballast and reflector required.
  • Short lifespan.


As the name suggests, a fluorescent lamp or tube uses fluorescent lighting to produce visible light. It works by passing electrodes placed at both ends of the light bulb. As the electric current moves, the mercury in the bulb absorbs energy and creates short-wave light that illuminates a fluorescent layer in the bulb.

Fluorescence does not emit as much light as HIDs. Therefore, they are widely used for seed starting, rooting cuttings, and for the vegetative phase of early to mid-stage plants.

Two common types of fluorescent lighting for indoor plants are fluorescent lamps and compact fluorescent lighting (CFL).

Tube-shaped fluorescent lamps

There are many shapes of tube-style fluorescent tubes namely T5, T8, and T12. Of these, the T5 is the most popular and most efficient for indoor growing.

The T5 emits less power than HIDs, which means it has a much cooler temperature and can be kept closer to plants

CFL (compact fluorescent lamp)

CFLs are short, twisted light bulbs that can be found in every home. When CFLs were invented, they replaced the old light bulbs because of their long life and efficiency.

There are my sizes and colors CFLs that can be used for daily activities as well as growing from 12 watts to a maximum of 250 W.

CFLs are just a short version of Fluorescent. So it fits in smaller grow rooms than other types of lights. These lamps are relatively inexpensive. It doesn’t generate much heat. You do not need a lot of ventilation


  • Relatively cheap.
  • Runs cool and can be placed near plants.


  • Not as strong for bloom as HIDs (HPS)
  • Short service life (approx. 10,000 operating hours)
  • Ballast and reflector required.

Fluorescence makes light peaks grow:

Fluorescent lights are an efficient, cost-effective solution for beginners and an excellent addition for experienced growers. They are an excellent option for young plants, clones and the vegetative growth phase of plants as the lamps are not as powerful as HPS or high power LED lamps.

That means you can use fluorescent lights for all growth stages if your settings are small. However, if you want a better approach when plants enter the flowering stage, it is better to use HPS or LED grow lights that will produce much higher yields.

LED (light-emitting diode)

LED arrived later compared to other types of lighting. Initially, it was met with skepticism by private users and producers. However, LEDs quickly proved their worth by operating efficiently and having some striking unique benefits that other types of grow lights cannot.

LED grow lights are widely used today by both hobby growers and commercial greenhouse construction companies. This is because LEDs are energy efficient, give off little heat, and require little maintenance.

Users can adjust the LEDs to emit a specific wavelength of light they want.


  • LEDs usually have a built-in cooling that can be used to regulate heat around plants. So no ventilation and frequent checks at growers.
  • Little heating. You can place the LEDs near plants, which gives you great versatility.
  • Better lifespan. LEDs have an average lighting hour of 50,000 hours, which can last up to 15 years, compared to 10,000 hours on HP.


  • High initial setup costs. In the long run, however, LEDs no longer cost because of their efficient performance.
  • LEDs need space from the plants. Although the temperature is cool, too much light can burn plants.
  • Sensitive to ambient temperatures. This only happens in places where the temperature is very high (such as processing plants). The performance of the diodes of LED lamps depends on the ambient temperature. Too hot and the LED module could burn out.

Why Do Plants Need Light?

All living things need the energy to grow. People get energy from food. Plants get energy from light through a process called photosynthesis. The photosynthetic reaction can be explained as follows

Carbon dioxide + water + (light energy) -> glucose + oxygen

During this process, plants receive light energy from chlorophyll in their leaves. The energy is used to react carbon dioxide (from the air) with water (taken up by the roots and transferred to the stem and leaves) to create a sugar called glucose. This sugar is consumed during breathing or converted to starch and then stored. The by-product of the process is supplied with oxygen.

Many criteria will help you choose the best grow lights for your indoor garden.

Color (light photosynthesis spectrum)

How does light color affect plant growth?

The light spectrum

We use a parameter called the spectrum of light to know the wavelength of light. The spectrum, measured in nanometers, is very useful for explaining how light affects plant growth.

For indoor growers, the specific band to consider is between 400 and 700 nanometers, also known as Photosynthetic Active Radiation (PAR).

We use different nanometer ranges for different growth phases of plants. Specifically,

The blue light in the range of 400 to 490 nanometers is used during the growth phase of vegetation and foliage.

The orange-red light between 590 and 700 nanometers is used during the flowering and fruiting phase.

The green light of 490-580 has little effect on plant growth as plants are naturally green. Your cellular chloroplasts absorb blue and red light but skip green when they reflect that color.


Intensity is the amount of light to which plants are exposed. This depends on the type of light used, the power (watts) of the bulb, and the angles/positions of your bulbs.

Duration (photoperiod)

Photoperiod means the duration of the flash to which you expose the plants. According to How to Hydroponics, Keith Roberto. Usually, plants grow best under 16 to 18 hours of light per day. Greater exposure does not appear to improve plant growth in all cases. Plants that indicate photoperiod, namely the traits that cause day length flowering, should be lit for 12-14 hours when flowering is required. The next dark cycle and the plants should be kept in complete darkness for fruits and flowers to form properly. A timer is used to control the duration.

Plant Variety And Growth Phase

Different types of plants may require different light levels. For example, plants that live in the jungle don’t usually need as much light as plants from warm, sunny climates.

Also, the amount of light that plants need in different phases is not the same. You can of course consider getting a full spectrum to grow light to make it suitable for all growth stages.


This way you know how many lamps and types of lamps can best cover and illuminate your plants.

When lamps are placed far from plants, the number of lamps that plants require will absorb essentially little heat.

Each square foot of grow space typically requires 30-50 watts. The correct placement of lamps in your room is an important element that cannot be ignored.

How Much Light Do You Need?

The performance of the power depends on the light source.

To visualize a rough estimate, you typically need at least 30 watts per square foot. But 50 watts per square foot is optimal.

Now calculate the required lighting for the area you are growing.

Suppose you are lighting an area of ​​8 square feet and you need a minimum of 30 x 8 = 240 watts for the area. The optimal light output is 50 x 8 = 400 watts.

Different types of light produce different outputs. So a CFL that puts out 400 watts can correspond to 200 watts HPS lamps. The layout of the room, growing style, reflector, and environment can also influence the required lighting.

Pay close attention to the plant growth and adjust the light output.

Tips for easy placement

Hanging or placing lamps above the plant beds or pots is the best arrangement, as it mimics natural sunlight from above and exposes all sides and leaves of a plant to the artificial light.

As a rough guideline, incandescent bulbs should be at least two feet above your plants. Fluorescent and LED lights have a lower heat signature, so they can be placed 12 and 6 inches above plants, respectively.

Continue to adjust the grow light position as your plants develop and mature to maintain proper spacing. Please refer to your specific model and type of design for full details and instructions.

And remember, the lighting level required for indoor growing will depend on the characteristics of the particular plant being grown. Depending on what you plan to grow, you may need different lights at different heights for specific areas of the plant.

How long should the grow light stay on?

Different types of plants require different amounts of light. As a rule of thumb, most vegetable and flowering plants require 12 to 16 hours of light per day, with flowering plants being on the higher end of this range. Plan to give most plants a minimum of 8 hours of darkness per day.

Darkness is actually very important to the growth cycle of plants. During the day, sunlight helps plants produce energy through photosynthesis. At night, however, plants break down this energy for growth and bloom in a process called ‘breathing’.

Check your seed packaging or plant labels, or ask the kindergarten for specific suggestions. And make sure to turn off your grow lights now and then. Nobody likes to work 24 hours a day, not even plants!

As the plants grow, increase the light accordingly to maintain the optimal distance, which will vary depending on the type of light bulb being used and its wattage (the higher the wattage, the further away the bulb can be). These are the basic parameters:

  • Fluorescent Grow Light: 3 to 12 inches
  • LED grow light: 12 to 24 inches
  • HID Grow Light: 24 to 60 inches

Light Bar: Ideal for high-density production, but beware of excessive heat!

All in all, LED light bars are a great way to give your plants the light they need to grow at higher densities. While there are many options on the market with unique features and a range of performance requirements, one thing remains constant – you have to be careful about how much heat they generate.

Unlike LED lights, this particular form factor does not come with active cooling elements such as fans, and growers need to understand how to handle excess heat in their growing environment.

Keep in mind that uncontrolled heat increases the potential relative humidity of the growing environment, leading to increased disease rates and other plant problems such as burns. In extreme cases, this leads to drought stress and tissue death. So make sure you know how to deal with heat stress or find a lamp to do it for you!

How To Install Grow Lights

Installation requirements vary drastically depending on the size of your indoor garden and the type of light bulb used. But here are a few basic steps to get you started.

Check how many lamps you need.

Most edible plants require at least 30 watts per square foot, but fruits (such as tomatoes) generally do not produce high-quality abundant plants without 40 to 50 watts per square foot. The power is always stated on the lamp package. Simply multiply the area of ​​your grow surface by the number of watts you want to deliver (between 30 and 50). Then divide by the number of watts provided by the bulbs you want to use.

Develop a light shelf.

You need a way to keep the bulbs at the correct height above the plants. And unless you’re growing something that stays more or less at the same level throughout its life, you have to raise the light shelf and the plants will grow. This is usually accomplished by some sort of pulley system or by hanging the lights from a metal chain. This way you can easily adjust the height by changing the limb from which the lamp comes.

Add the necessary equipment.

It is generally advisable to set your lights on a timer to make sure they are receiving the correct amount of light and that they are received at the same time every day. are available for indoor growing, although a standard will work as well. If your lights in your grow room reach temperatures over 80 degrees, install a ventilation system to avoid heat stress. Enthusiasts use reflectors and all kinds of other grow light accessories to get the best results.

Things Indoor Farmers Should Know About LED Grow Lights

Lighting is the most important aspect in creating the perfect indoor farming environment. This could be a decision for your indoor farm. It is therefore strongly recommended that you spend sufficient time planning and designing the layout of your systems and fixtures. The use of CAD (Computer-Aided Design) is strongly recommended. The design must be optimized so that no light is wasted.

There are unique techniques to make more use of the available light in a room. Since white surfaces reflect light, make sure you have as many white surfaces as possible. All bright surfaces that reflect light work the same way. You can also use light movers to distribute the light over a larger area.

Finally, it is important to keep up to date with the latest trends and technologies evolving in indoor growing. Use a systematic approach and be open to new opportunities.


If your budget is tight and you have limited growing space, essentially opt for CFL lights. They are inexpensive, easy to install, and easy to replace. Still, CFLs deliver decent results that have proven themselves over the years.

You can also use HPS lamps alone or, even better, in combination with MH, CMH, or CFL lamps. They are also very affordable and give reliable results. Since HPS has a high temperature when you use it, you should be ready to cool it down.

If you are looking for an efficient grow light device for long-term use then LEDs are an excellent option. Their price is high, but they make the most of your money with the cool operation, long life, and low power consumption. And best of all, it brings great yields.