How to Choose a Grow Light for Plants


If you’re planning on growing any plants indoors, you’ll likely need a grow light. A grow light is a light that supplies your plants with artificial sunlight, so you can grow them anywhere, year-round.

As you may know, plants require sunlight to make their own food as well as keep them warm, so it is critical they get the right amount of it. But how do you choose a good grow light for your indoor plants?

Grow lights are good for indoor plants that need access to sunlight to grow, but might not be getting it naturally. When choosing the right grow light for your indoor garden, some things to keep in mind are the type of plants you’re growing, the space available, and the spectrum of light required.

If you’re looking for a definitive guide to picking the best grow light for your indoor gardening setup, look no further. Read on to find out all about how grow lights work, how to determine your plants’ individual needs and find the grow lights which meet those needs.

How to Choose a Grow Light for Houseplants

If you have just one or two houseplants, you’ll probably find that sticking them near a window will give them enough sunlight to thrive. However, if you want to devote more space to your indoor garden, you might want to consider adding some grow lights to your indoor garden setup. These lights allow you to garden in areas that are removed from natural sunlight, like a basement or garage.

There are lots of differences between grow lights available on the market, and the one you choose will have to fit your needs the best. You’ll likely place a pretty high priority on the price since you don’t want to spend a fortune on your grow lights. The types of plants you’re growing will also play a role in your decision as different plants do better under different types of light.

There are a huge variety of grow lights available, and the vast amount of choices can make picking just one or a few pretty overwhelming. Luckily, there are ways to narrow down your selection pool to help with your decision making.

There are a variety of factors you should consider when choosing a grow light for your plants, which  include:

  • The type of plants you’re growing
  • Ease of use of the grow light
  • Type of bulb needed
  • Energy output and energy requirement
  • Size and shape of the grow light
  • Amount of space available
  • Price

In short, knowing exactly what your needs are is the best way to choose a grow light for your indoor garden. Only by knowing your requirements will you know how best to fill them from the plethora of choices available on the market. This article will discuss the differences between grow lights and how you can best evaluate them to fit your needs.

What Grow Lights Are Good for

Grow lights are good for when you want to grow plants indoors. They’re especially good in areas of your house that don’t get regular access to sunlight. For instance, grow lights might come in handy if you have a large basement in your house and want to turn it into an indoor garden.

In this case, since your basement probably doesn’t get a lot of sunlight, you can set up some grow lights to make sure your plants get the right kind of light they need to conduct photosynthesis and grow their own food.

Grow lights are also good if you live in an area that might not be suitable for planting outside, or if you want to garden year-round. You can’t garden outside in the winter, but with a good set of grow lights, you can garden indoors for the entire year.

Grow lights are also good for growing seedlings inside. You may want to start your seedlings indoors until they’re able to survive in harsh elements outside, but you’ll be limited by how much sunlight you have. With grow lights, you can grow a larger number of seedlings quickly. They’ll also turn out hardier and stronger than seedlings that were grown without grow lights.

Jalape_o_Pepper_Lines (4)
Jalape_o_Pepper_Lines (4)

How to Use Grow Lights for Plants

How you set up your grow lights is largely determined by what type of bulbs you’re using, as well as your gardening setup. There are many different light fixtures available that can cover a row of plants or single fixtures for a small radius of plants.

In general, you’ll want to hang your grow light above the plant with a distance between them that’s recommended by the light manufacturer. You’ll also need to make sure you have space above your light to move them up, as you’ll have to move them as your plants grow taller.

The type of bulb you choose will determine the distance you should have between your plants and the bulb. Fluorescent bulbs put out the least amount of energy, so they usually need a separation of between 6 and 12 inches. LED bulbs put out more energy, so you have to hang them a little higher at 15 inches or higher.

When to Use Grow Lights for Plants

Grow lights are handy when you’re growing plants indoors, and they might not have daily access to sunlight. Plants need a lot of sunlight to grow effectively and depending on the type of plant, might need anywhere from 8-18 hours of sunlight a day (more on that later).

Grow lights allow you to do multiple things, including start seedlings off on the right foot, grow a large number of plants indoors in a place removed from sunlight, and have an indoor flower garden that’s beautiful year-round. If you love to garden but live in an area where you can’t do it during the winter, you may want to look in to grow lights as a solution.

Types of Grow Lights

There are two basic types of lightbulbs you’ll be evaluating when choosing your indoor grow light setup: Light Emitting Diodes (LED) or fluorescent bulbs.

Which Light Type is Better: LED or Fluorescent?

Both have their advantages and disadvantages, which we’ll discuss below. Neither of them is better per se; they each have different applications and strengths that make them better in certain situations.

LED Lights

Pros:

  • Low heat emission
  • Efficient energy consumption because the light is directional
  • Wide range of light spectrum to use for a variety of plants
  • Longer bulb life
  • Environmentally friendly

Cons:

  • More expensive upfront
  • High energy output means they need to be farther away from your plants

LED lights are a popular choice for many indoor gardening operations because they are energy efficient and don’t put off a lot of heat. LED lights come in a lot of different colors on the light spectrum as well, so you can get the exact heat emissions you need for whatever plants you’re growing. Some plants grow better under different spectrum ranges.

LED lights are more expensive to purchase, however, so you’ll have higher upfront installation costs. They also put out a deceptive amount of energy, so to avoid damaging your plants, you’ll have to place them farther away, which may require you to have more space. They do, however, last a lot longer than fluorescent bulbs, so you’ll replace them less often over time.

Fluorescent Lights

Pros:

  • Requires less indoor space, as you can leave them closer to your plants due to lower output
  • Less expensive installation costs
  • Bulbs can be available in the full spectrum of light

Cons:

  • Burn out quicker, so you need more over time so they can more expensive in the long run
  • Less energy-efficient than LED bulbs
  • Put out energy all around the bulb, not directional
  • Not very environmentally friendly

Fluorescent bulbs are the other major type of light bulbs available for indoor grow lights, and they remain a popular choice. Their inexpensiveness is one of their greatest draws, but they’re also a good all-around bulb choice for a variety of different applications. They’re also available in a variety of spectrums, but most of the bulbs you find will be blue.

Fluorescent bulbs burn out more quickly than LED bulbs, however, so you’ll have to replace them more often. They’re also much less energy efficient since they’re not directional, which means they put out heat and light all around the bulb. They’re also not environmentally friendly, especially for disposal, because of the mercury inside of them.

Does the Grow Light Color Matter for Plants?

You may or may not know that light comes in a spectrum with different colors. Each color is a different wavelength of light. In the spectrum of light that’s visible to the human eye (red to violet), red light has the longest wavelength, while violet has the shortest. Plants need different colors of light to grow best, and when they grow outside, they receive them from the sun.

Your grow lights, however, aren’t the sun. Although many of them are full-spectrum, it still helps to know how different colors of light affect plant growth. In general, plants need blue and red lights to grow effectively. Red light helps them produce flowers, while blue light helps them become lush and green.

Of course, plants really need a variety of colors of light, and how much of a color they require depends on their stage of growth. Green light helps seedlings and young plants grow, but it doesn’t seem to do much after they’ve passed the seedling stage.

How Many Lumens of Light do Plant Need

There’s no hard and fast rule for how many lumens plants need to grow. Each plant is different, and to add to the complexity, plants have different needs at different stages of growth. A lumen simply refers to the light output of a light source. Each grow light is different as well, with the number of lumens dependent on the wattage as well as the type of light.

Numbers vary wildly on the internet in terms of how many lumens your plants need to thrive, with estimates ranging from 300-800 lumens per square foot to 7,000-7,500 lumens per square foot. Again, this is dependent on the type of crops you’re trying to grow.

All in all, lumens aren’t a very effective way to measure the amount of light your plants are getting. A more useful way to determine the light needs of your plant is to measure it in what’s called PAR, or photosynthetically available radiation. It’s a measure of the light wavelengths that stimulate photosynthesis in your plants.

This leads back to the colors of grow lights. Peppers, for instance, need light in the blue spectrum early in life because it stimulates root and stem production. Once they’ve developed a healthy foundation, red light then stimulates flowering and fruit production. While the whole spectrum of visible light is important to peppers, blue and red, seem to be the most important.

Best Plants to Grow with Grow Lights

With a little determination, you can grow pretty much any sort of flower or fruit or vegetable producing plant under grow lights, but you’ll have your lights on for a long time with some varieties.

The key thing to remember is that plants have different sunlight needs. Plants that need more sunlight will therefore need lights on longer, which will burn your bulbs out faster and cost more in energy consumption.

How Many Hours of Grow Light Does a Plant Need

Plants can be split into two categories: full-light plants and partial-light plants. The names are self-explanatory: plants that need full access to sunlight all day are full-light, and plants that can thrive in the shade or with only partial access to sunlight are partial-light plants. Some examples of full-light plants are:

  • Pumpkins
  • Tomatoes
  • Cucumbers
  • Butternut squashes
  • Zucchini
  • Peppers

Some examples of partial-light plants include:

  • Lettuce
  • Peas
  • Carrots
  • Leafy greens
  • Root vegetables

Generally speaking, vegetables that are mainly leafy greens like lettuce have the lowest requirements for light, and they can thrive in shaded areas with only a few hours of sunlight per day. Root vegetables need a little more but don’t need full sunlight either. Plants that grow large fruits or vegetables need the most light.

All of this can be translated into your indoor growing operation. Plants that need a lot of sunlight will need the same approximate hours of grow light exposure. You can take the requirements for sunlight and apply them to grow lights as well.

How to Choose the Right Size Grow Light

The right size grow light is one that fits the size of your indoor garden. In general, you need 20 to 40 watts of power per square foot of space. Depending on the amount of square footage you have, you may need several fixtures, but this is a good rule to go by. In other words, a 1,000-watt system would provide enough power for a space of 25-50 square feet.

If you have long tables full of plants, you may need to raise your lights higher so they can reach all your plants, or you might need to have multiple fixtures to cover the whole setup. The exact setup will be based on your situation. Luckily, there are plenty of different grow light fixtures available to meet your needs.

How Long do Grow Lights Last

How long your grow lights last will depend on the types of grow lights you decide to go with. LED light bulbs, which have a much longer life, will last around 50,000 hours per bulb for cheaper models, and up to 100,000 hours per bulb for higher-end models. Fluorescent bulbs, on the other hand, will last around 20,000 hours or so.

Best Way to Hang a Grow Light

You will want to hang your grow lights with a way to raise them easily, so hanging them from a rope or small chain pulley system is best. You do not want to have to re-hang your lights every time your plants grow. As your plants grow taller, you can easily shorten the rope or chains holding them up to raise your lights. When grow lights are hung from a pulley system you can lower the lights back down when you’re going to start growing a new crop.

Can You Leave a Grow Light on for 24 Hours?

Most plants need a period of less or no light to grow effectively. While leaving your light on for long periods can help them grow faster and have a better yield, you shouldn’t leave your grow lights on for 24 hours. 

Can a Plant Get too Much Artificial Light?

As mentioned above, a plant can get too much artificial light. If your plants look withered and like they’re burned out, you may need to cut back on the amount of light they’re getting or move the lights farther away.

Closing Thoughts

If you’re planning on growing any sort of plant indoors, it pays to be aware of the options you have for grow lights. Providing high-quality light to your plants is very important to their growth, and you have a few options in the form of fluorescent or LED bulbs. Choosing a grow light is a critical piece of your indoor garden, and you should make the decision carefully.

Supriya

Hi! I'm Supriya. I'm a home cook, bulldog mom, spicy food lover, and founder of The Spicy Trio. I have been a home cook for about 15 years and have been growing plants for the past six years.

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