When To Use A Growing Light In A Greenhouse

It cannot be obvious to know when to use a growing light in a greenhouse, so remember that it’s when the existing light intensity is not optimal and if the growing plants need it. The Auburn University Office of Sustainability has mentioned that one of the advantages of greenhouses is that you can have full control of the environmental conditions. And one of these conditions relies on artificial light, so you must know how to use it correctly. 

Gone are the days when farmers have to worry about extreme and unpredictable weather because greenhouses allow productivity all year round, including tripling crop yields. However, it’s essential to learn the requirements of your plants to guarantee this impressive success. Below is a guide on when to use a growing light in a greenhouse. 

When To Use A Growing Light In A Greenhouse


When To Use A Growing Light In A Greenhouse Correctly


Supplementation needed

We all know that plants need light to perform photosynthesis, so a successful greenhouse should provide this in addition to other optimal conditions. According to Cornell Information Technologies, natural sunlight is sometimes enough for the greenhouse. But in some cases, this leads to problems in temperature that can affect the plants negatively. 

As a result, greenhouses use cooling systems and reduce the light levels to control the temperature. This can then potentially lead to another problem, which is the lack of light. In this case, you want to provide a growing light to support the plants. 

Another example that dictates when to use an organic light in a greenhouse is during the winter months. In the Northeastern and Northwestern parts of the US, the cloudy conditions affect the amount of light that could get in the greenhouse. This is where using a growing light is going to be necessary. 


Young plants vs. mature plants

A growing light, from the name itself, is something you’ll use for the greenhouse to support your plants’ optimum growth. However, it’s worth remembering that different plants and vegetables vary in their requirements for growth. Michigan State University even mentioned that light plays a role in the fruit yield of plants. 

Once your seedlings germinate, you’ll notice the effect of the light levels to their growth. If the growing plant does not receive enough light, it will end up weak with thin stems. And even if it survives to mature, the stem will not thicken. 

As your plants grow, you may need to use a higher growing light intensity to ensure that even the older leaves receive light as much as the new ones. Simultaneously, the type of plants you’re growing will also affect the need for a growing light in a greenhouse. For example, you will need a growing light for plants moving into the fruiting or flowering phase during the months with limited natural light. 

In North America, you will need to use a growing light to support tomato production because it usually happens at the end of October. On the contrary, some plants grown for vegetative parts may not need a growing light since they stay at this growth stage anyway. Still, low light levels during winter may require you to have a growing light to prevent plant growth from slowing down. 


How Long Should You Use A Growing Light In A Greenhouse?

As mentioned previously, the light requirements for each plant vary. Therefore, the duration of usage of a growing light in a greenhouse will depend on the plants you have. You can classify your plants in long-day and short-day groups to make the planning of growing light duration easier.

Long-day plants will grow best and undergo the reproductive phase when the day is long, while short-day plants would be better if the night is longer. This is why some plants will start to flower even in the fall. And since short-day plants like herbs are grown for their vegetative phase, you can use an organic light to extend the day length. 

Overall, the success of your greenhouse is affected by the light it can provide. It’s crucial to know your crops’ individual lighting needs while also being mindful of the other requirements they need to thrive. At the same time, it’s worth noting that failure to meet the proper spacing on your crops can also affect the amount of light. 


Can You Have Too Much Light In A Greenhouse?

You must maintain the optimal lighting conditions in the greenhouse because too much light also equates to high heat energy that can affect the plants. This is where the balance of light and temperature is vital in a successful greenhouse. For temperature control due to too much light in the greenhouse, you can use cooling systems, evaporative cooling, and shadings. 



A successful greenhouse depends on the planning and execution of each crop’s optimal growing conditions and requirements. Knowing when to use a growing light in a greenhouse is one of them, so note that it’s during the times when the existing light intensity is not optimal and if the growing plants need it. Each plant and growth phase may require a specific depth and duration of growth, which means careful planning and preparation are mandatory. 

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