Skip to main content

Greenhouse lighting requirements: What you need to know

It may seem obvious, but plants require light to grow. That just blew your mind, we know. However, many plant enthusiasts do not provide adequate light for their plants, inside a greenhouse or outside. Greenhouses require light to promote crop growth and yield, playing the main role in photosynthesis. Yet greenhouse lighting requirements can be confusing, including the types of lights, amount of light needed each day, and the light spectrum.

In the summer it is crucial to provide enough shade for your plants. In winter, lighting requirements change. We’ll provide you with greenhouse grow light information to help your greenhouse flourish year-round.

asharkyu / Shutterstock

What light is needed for plant growth?

The best balance of light for a plant to grow well is a split of cool and warm light, replicating natural sunlight. Depending on the type of plant and the stage of cultivation, you will need a lamp with a specific spectrum range. A spectrum is a range of different light wavelengths being emitted from a light source. Other colors of light can help different plants achieve unique goals. For example, next time you buy bulbs, take a look at the packaging. You will most likely see a number, something like 2700K or 3000K; these numbers indicate the coolness or warmth of the light spectrum.

In general, plants need more blue light when growing and maturing and then need red and orange light when blooming and producing. Let’s take a look at the different types of greenhouse lights and what spectrum they produce.

Greenhouse lights in large greenhouse
Photo By pipicato/Shutterstock

The types of greenhouse lights

You will encounter four main types of lights that are normally used in greenhouses. You have probably heard of some of these before (or at least their acronyms):

  • Incandescent
  • High-intensity fluorescent (HIF)
  • High-intensity discharge (HID)
  • Light-emitting diode (LED)


You might not see these types of lights anymore, but at one point they were the standard in homes around the country. However, governments around the world have begun phasing out these lights because they are not energy efficient. They aren’t great for using in a greenhouse, either. Incandescent bulbs work by heating a filament inside the bulb to glow with visible light. Because of the heat they give off, you should not place them close to the foliage.

Overall, these are the cheapest option (if you can find them) and while they are a good source of red wavelengths and could trick your plants into thinking the sun is still up, there are far better options for your greenhouse that aren’t expensive.

High-intensity fluorescent

In comparison with the incandescent bulbs that waste heat, high-intensity fluorescent (HIF) bulbs are much more efficient by converting electricity into light without wasting heat. On the color spectrum, these bulbs produce a lot of blue light and not a lot of red, while also providing a full white light spectrum. If you go with this option, find a T5 fluorescent bulb as these produce three times more light in both blue and warm spectrums.

Overall, HIF bulbs are a good option for a greenhouse that might not get a lot of natural light. They are useful for propagating and grow rooms and, if you have a large space, the energy efficiency of these bulbs could be useful in saving you money.

Light-emitting diodes

Going up on the efficiency scale, light-emitting diodes (LED) bulbs are more expensive than the other options but use half the electricity and last five times longer than fluorescent bulbs. Their light intensity is also much greater and produces a full spectrum of light. They are also tiny compared to other bulbs making them very easy to install.

Overall, LED lights are one of the best options for a greenhouse because they maximize the blue and red light spectrum, which enables photosynthesis. LED bulbs can also be used for all stages of growth.

High-intensity discharge

If there is one type of greenhouse light we recommend, it is high-intensity discharge (HID) bulbs. They are efficient at producing light and increasing light intensity; many growers use HID lights in their own greenhouses. There are two main types of HIDS: high-pressure sodium bulbs, which are used to promote growth and flowering and are rich in red light; and metal halide lights, which are used to support vegetative growth and provide more blue light.

However, there are two main disadvantages with HID lights. First, they are not as practical compared to LEDs because they must be installed on heavy ballasts that are sold separately, plus they are quite bulky and take up a lot of space, not ideal if you have a tiny greenhouse. Second, HID lights produce a lot of heat so you must place them between 30 to 36 inches away from your plants. Again, not ideal if you don’t have a lot of space.

Final thoughts

Plants require different wavelengths of light in different stages of growth. While many greenhouse lights will help with growing your plants, some are better than others. If you have the space, time to set them up, and want to hand over the money, HID bulbs are the best option. If you don’t have a lot of space in your greenhouse or want a more practical option, LEDs will work wonders. However, each plant is different; if one type of bulb doesn’t meet your goals, then test out another one and keep trying until your greenhouse is blooming.

Editors' Recommendations

Niko Vercelletto
Former Digital Trends Contributor
Niko Vercelletto lives in Lansing, Michigan. He is passionate about going into depressive spirals thanks to the Detroit Lions…
What you need to know about growing sugar snap peas in containers
Easy-to-follow tips for growing sugar snap peas in containers
Organic green sugar snap peas

An excellent way to enjoy the full flavor of sweet, freshly picked sugar snap peas is to grow them in containers. If you have limited room on a patio or porch garden, then using containers can help you maximize the space you have.

Sugar snaps are a crossbreed between garden peas and snow peas. They’re a variety with incredible versatility and can be used in their pods or shelled. When grown at home, sugar snap peas are significantly sweeter and juicier than store-bought peas. You can grow them organically without the use of toxic chemicals and pick them straight from the plant!

Read more
3 of the best solar garden lights for a bright and eco-friendly yard
outdoor sitting with lights

It's important to decorate your garden with stunning flowers and veggies, but it's also vital that your garden be well lit. Whether for parties, late-night harvesting, or quiet nights reading in the warm summer air, solar lights make a fantastic addition to any garden. They can transform a backyard into a cozy after-dinner area, light up a walkway for safe navigation, or bring attention to a favorite tree. Here we'll be going over the essential considerations to keep in mind while shopping for solar garden lights. We'll also include a few of our favorites you might want to add to your landscaping.

What to consider when buying a solar garden light
Not all solar garden lights are created equal; there are a few things you'll want to keep in mind.
The cost is one of the most important aspects of purchasing a new item for almost everyone. Although solar garden lights are very similar in price, it's still crucial to consider how much you're willing to spend on lights before you go looking. Having a better idea of your budget will help you find the ideal solution.
Ease of install
If you need something easy to put up for a party this weekend, you won't want to buy a setup that'll take hours to put together. Instead, finding a solar light that's easy to install will make life easier and allow you to get back to doing other things like gardening!
Outdoor products never last as long as their indoor cousins, so it's not surprising to find that solar garden lights have a shorter shelf life than other indoor lights. However, this doesn't mean you should have to replace your garden lights every year or bring them in during the winter. Instead, look for a light that can withstand the types of weather you often see and be sure to care for the light properly so it can last a long time.
Of course, you should like the way your new lights look! If they don't suit the aesthetic of your garden, you'll likely be disappointed and tempted to go looking for other options. So be sure you're looking for a light that's going to suit the rest of your garden, or at least blend in and not take away from your garden ornaments.
MAGGIFT Solar Pathway Lights
These pathway lights by MAGGIFT are ideal for lighting the way during the darker hours of the day. Whether it's the path from the driveway to the house or the deck to the flower garden, these lights will soak up sun rays and provide you with plenty of light to see your way.

Read more
A complete guide to cleaning your greenhouse for beginners

When you first installed your greenhouse, it probably looked like a glittery glass castle for your lovely plants to grow and live in. However, weather, soil spills, and birds have made their mark on your greenhouse over time and now it's probably looking cloudy and nasty. So how do you clean a greenhouse?
Why worry about a clean greenhouse?
You may be wondering if you even need to worry about cleaning your greenhouse. If you don't mind the dirty look, maybe you could leave it as it is? Unfortunately, it's much better for your greenhouse and your plants if you give the greenhouse a deep clean at least once a year. It'll make it easier to use when it is clean and organized, and the walls of the greenhouse need to be clear so they can let in as much light as possible. Additionally, a clean greenhouse is less likely to spread pests and diseases to your precious plants. And lastly, things last longer when you care for them and greenhouses aren't cheap.

When should you clean a greenhouse?
There's no right time to clean a greenhouse; whenever you can is better than not at all. However, we suggest cleaning it when there isn't so much to do in the garden and it isn't so hot out. Usually, the fall is when the garden chores slow down and it starts to cool out, making cleaning the greenhouse much easier on you.
What is the best way to clean a greenhouse?
You can use whatever cleaning method works for you, but here is our step-by-step process that we recommend.
Step one: Empty the space
Of course, we know you can only empty a greenhouse so much if you have tender plants that need to stay warm. But as much as you can, take out the tools, buckets, and bags of soil. It will be much easier on you if you don't have to fuss with items in your way as you clean the walls and floors. This also allows you to go through what you have and declutter if necessary.
Step two: Rough dusting
Over the season, spiders and bugs and maybe even some mice have tried to make homes in your greenhouse. This has probably led to a few cobwebs and dust piles around the corners. You'll want to remove these large areas of debris before you start the deep cleaning. Use a broom to knock down the cobwebs and sweep up the floor; you've probably spilled some soil during the summer!
Step three: Clean the walls
The panels of your greenhouse will now need to be deep cleaned. You can use a bucket of warm water and a sponge to wipe them down, but we also recommend bringing a long-handled brush to make life easier. This way, you can dip the brush into the bucket of soapy water and scrub down the walls with the long-handled brush. You'll be able to reach every inch of the walls without killing your back.

Read more