How Much Light Do You Need In A Greenhouse? (Find OUT)

Greenhouses are amazing places. They allow you to grow plants that would otherwise be impossible in your climate. You can grow tomatoes at the North Pole and cucumbers in Antarctica. 

The only problem is that greenhouses need light, and not just any old light will do. If you put too much light in your greenhouse, you’ll end up cooking all of your plants.

And if there’s not enough light? Well, then they won’t grow at all! So how much light do you need?

 Let’s talk about it:

I WISH I’d CHECKED This Earlier – Greenhouse LIGHT levels!
Understanding the light requirements in a greenhouse is crucial for successful plant growth.
The amount of light needed varies depending on the type of plants being grown.
Most plants thrive with 10-12 hours of light per day.
Balancing natural sunlight and supplemental artificial lighting is important for optimal growth.
Insufficient light can lead to weak plant growth and reduced yields.
Excessive light can cause overheating and leaf burn.
Monitoring light levels using a light meter helps maintain optimal growing conditions.
Different lighting options, such as fluorescent lights and LEDs, are available for greenhouses.


As you can see, the amount of light your plants need depends on when they’re growing. If your greenhouse is a self-contained ecosystem, you might have to adjust how much sunlight reaches it as the seasons’ change.

For example, during spring and summer months the busiest growing seasons, your plants will benefit from plenty of direct sunlight. Spring is when most people start seeds; this is also when gardeners begin to grow their crops outside. 

In this time period, it’s important for your greenhouse to receive as much natural light as possible (ideally 12 hours per day). 

On the other hand, fall tends to be less busy for growers since most produce has already been harvested or moved indoors for storage; however, if any crops are still in need of tending at this time of year then it’s imperative that they get enough light exposure so they don’t wither away.

When it comes to managing light in your greenhouse, shading your canopy plays a crucial role. Explore our comprehensive guide on how to shade a canopy to discover effective techniques for maintaining optimal light conditions.


The further north you are, the less light you will get. The further south you are, the more light you will get. And if you’re closer to the equator, more hours of daylight means more light available throughout the year.

Latitude RangeClimate Zone
0° – 23.5°Tropical
23.5° – 66.5°Temperate
66.5° – 90°Polar


Altitude: If you are at a high elevation, the sun’s rays will be weaker and the greenhouse will need more light. Plants will also need to be trained differently. 

For example, if you grow tomatoes at an elevation of 3,000 feet (910 meters) above sea level or higher, then it might be a good idea to train them horizontally instead of growing them vertically

Latitude: The farther north or south from the equator you are located on earth, the more likely it is that clouds will be above your greenhouse during certain times of the day. 

The farther north or south from the equator that one lives in North America, for example (as opposed to just Canada), there is usually less light available due to fewer hours of sunlight during winter months

Taking proper care of your gazebo canopy is essential for ensuring longevity and optimal performance. Learn valuable tips and techniques for treating your gazebo canopy in our detailed article on gazebo canopy treatment and keep your canopy in top shape.


Cloudiness is another factor that affects how much light you need in your greenhouse. Clouds block sunlight and can be a good thing or a bad thing, depending on your situation. 

If you want to keep the greenhouse warm, cloud cover can help by reflecting heat back into the greenhouse. 

On the other hand, if you want to keep your greenhouse cool and require more sunlight exposure than cloudy weather allows for, then clouds will work against your efforts.

There are many factors that determine how much lighting is needed in any given season; however, these are some of the easiest ones to manage so that you can maximize efficiency during all four seasons.

The Greenhouse Itself

Walls and ceiling: The walls and ceiling of your greenhouse will be the most important factor in determining the amount of light you need to provide. If possible, choose a material that lets in lots of natural light from the outside. 

Greenhouse kits are a good option for this, as they often have external frames made of plexiglass or other transparent materials.

Doors: Choose doors that open both ways so that you can adjust airflow when it’s hot outdoors. You should also make sure your door can swing outwards if you need to access items stored in the greenhouse through another door (this might not be possible with some kits).

Windows: If possible, choose windows with large panes of glass rather than small ones; these will allow more sunlight into the room during winter months when temperatures drop below freezing outside (and vice versa). 

Large-paned windows may also help reduce condensation inside the greenhouse if there’s too much water vapor buildup due to high humidity levels within it but if you’re worried about over-heating your plants during summer months and want an extra barrier between them and direct sunlight exposure while still letting in plenty of light on sunny days then consider installing shade cloths instead (more on this later)

Greenhouse Type
Glass Greenhouse
Polycarbonate Greenhouse
High Tunnel
Shade House
Lean-To Greenhouse

The Shading Agent

Shading agents are used to controlling the amount of light that enters the greenhouse. They can be curtains, film, or glass. The shading agent will also affect temperature and humidity levels in your greenhouse.

Choosing the right covering material is vital when it comes to protecting your greenhouse and optimizing light transmission. Discover the benefits of polyurethane and how to effectively cover your greenhouse in our informative guide on covering a greenhouse with polyurethane.

The Time Of Day

You’ll want to adjust your lighting schedule based on the time of day. Plants need more light in the morning and less later on, so if you’re using supplemental lighting in a greenhouse, you may need to readjust it as the day progresses.

Whether Or Not You Have Supplemental Lighting In The Greenhouse

The amount of light you need to achieve optimum plant growth is determined by the number of hours per day that your plants receive natural sunlight. 

If you have supplemental lighting, the amount of light required depends on how much light is provided by natural sunlight and how much supplemental lighting you use.

If you do not have supplemental lighting in your greenhouse, the natural light coming through windows or doors will be enough to grow most vegetables and herbs. 

However, some types of plants do better when grown under artificial lights (such as tomatoes), while others prefer more shade (like lettuce). So it’s best to know what type of plants you plan to grow before deciding whether or not supplemental lighting is necessary for your greenhouse.

Plants And Their Light Requirements

Not all plants require the same amount of light. Some plants, such as corn, may need a lot of light to grow, while others thrive in shadier conditions. 

The type of plant and its exposure to sun and shade are also important factors that determine how much sunlight it needs.

What is the best amount of daylight for your greenhouse? There are no hard-and-fast rules here because every area has different levels of available sunlight and growing conditions. But generally speaking, more daylight means faster growth and faster growth *is* good.

Proper irrigation and watering are essential for maintaining a healthy greenhouse environment. Find out how to optimize watering efficiency by arranging sprinklers strategically in our insightful article on arranging sprinklers in a greenhouse. Ensure your plants receive the right amount of water and light.

Your Purpose For Growing Plants In The Greenhouse

Consider what you want to grow in your greenhouse. If you’re growing plants strictly for food, you’ll need more light than if you’re growing them for ornamental purposes. And if you’re trying to cultivate medicinal plants or herbs, then even less light will be required.

Commercial Production
Research and Experimentation
Nursery and Propagation
Home Gardening and Hobby
Education and Learning

The Temperature Of The Greenhouse

When you’re designing your greenhouse, you’ll want to keep in mind that the temperature of the greenhouse will affect how much light your plants receive. The plants themselves have different requirements for light and temperature, which means that if you want to optimize their growth, you need to balance these two factors.

The most common way of doing this is by selecting a type of lighting system that’s appropriate for the type of garden you want and then using fans or other cooling elements when necessary (see below).

Waterproofing your greenhouse is crucial for protecting it from water damage and maintaining ideal growing conditions. Discover an easy and effective method for waterproofing your greenhouse in our comprehensive guide on greenhouse waterproofing. Keep your plants safe and your greenhouse well-insulated.


The answer to how much light you need in a greenhouse depends on a number of factors. It can be difficult to get an exact answer because there are so many variables involved.

Further Reading

Crop King: How Much Light Does a Greenhouse Need?: Explore this comprehensive blog post that delves into the topic of greenhouse lighting requirements, providing valuable insights and tips on optimizing light conditions for successful plant growth.

Growing Greenhouse: Greenhouse Lighting Requirements: Discover the essential lighting requirements for greenhouses and learn about different lighting options and techniques to ensure your plants receive the necessary amount of light for optimal growth.

Greenhouse Today: How Much Sun Does a Greenhouse Need?: Dive into this informative article to understand the importance of sunlight in a greenhouse, and explore factors to consider when determining how much sun exposure your plants require.

Now, let’s move on to the FAQs section in markdown language:


How much light is needed in a greenhouse?

The amount of light needed in a greenhouse varies depending on the type of plants being grown. However, as a general rule, most plants thrive with 10-12 hours of light per day. It’s important to provide a balance between natural sunlight and supplemental artificial lighting if necessary.

What are the effects of insufficient light in a greenhouse?

Insufficient light in a greenhouse can lead to weak and leggy plant growth, decreased flowering and fruiting, and an overall decline in plant health. Plants may become etiolated and struggle to photosynthesize properly, resulting in reduced yields and lower-quality produce.

Can you provide too much light in a greenhouse?

Yes, excessive light in a greenhouse can be detrimental to plants. It can cause overheating, leaf burn, and even plant stress. It’s important to strike a balance by considering the light requirements of specific plant species and implementing proper shading or diffusing techniques if necessary.

How can I measure the light levels in my greenhouse?

Light levels can be measured using a device called a light meter or lux meter. These meters provide readings in lux or foot-candles, allowing you to assess the intensity of light in your greenhouse. Regular monitoring of light levels can help ensure optimal growing conditions for your plants.

What are the different types of greenhouse lighting options?

There are various greenhouse lighting options available, including natural sunlight, fluorescent lights, high-intensity discharge (HID) lamps, and light-emitting diodes (LEDs). Each type of lighting has its advantages and considerations, such as energy efficiency, spectrum, and heat output. Selecting the right lighting option depends on the specific needs of your plants and the greenhouse environment.