You only need two factors to know how to use a grow light in a small polytunnel, identifying the correct colour and the type of light. With the extensive list of grow lights available in the market, it can be overwhelming to understand how to use one on polytunnel shelving. Therefore, learning these two factors first should know the proper usage of a grow light in a small greenhouse.
A regular check-up of the indoor conditions is necessary to maintain a small greenhouse. Failure to provide the optimal conditions indoors will affect your plants’ growth, health, and productivity. If the small polytunnel has inadequate light, plants won’t manufacture carbohydrates and lose their energy reserves.
Much like maintaining a regular greenhouse, do not make the mistake of overlooking the usage of grow light in a small greenhouse. Grow lights may be smaller, but the plants’ requirements growing inside are still the same.
Comprehensive Guide On How To Use A Grow Light In A Small Polytunnel
The correct colour
One of the most confusing aspects when using a grow light is knowing what colour to use in the greenhouse. There is no difference with the correct colour to use, whether you’re using a small or regular greenhouse. The bottom line is that you want lights with wavelengths of red and blue.
Red and blue
The grow lights in the polytunnel may seem white to the naked eye, but they have wavelengths. Red and blue lights are best for growing lights because they affect how the plants synthesise nutrients. Therefore, they are responsible for energy and growth.
Choose lights that manufacturers label as balanced, full-spectrum, or natural.
High spectrum vs low spectrum
Additionally, some grow lights may have numbers indicating 400K or 2700K. Use this as your guide, where the higher the number, the colder the light. A broad range is why most UK gardeners who use grow light to encourage foliage to choose 6500K.
On the other hand, your plants will also need a warm grow light at 3000K if you’re focusing on fruit production. Keeping this in mind, you can start with high spectrum lights for producing seedlings. Afterwards, use low spectrum bulbs to help with flowering and fruiting.
The type of light
The most inexpensive light that you can use in the small polytunnels is incandescent. However, they get hot fast, so you have to ensure a safe distance of around 24 inches away from the plants. Besides being cheap, incandescent bulbs are also easy to install.
However, they have a short lifespan compared to others, and replacement will be more often.
The University of Missouri Extension mentioned that fluorescent lights are one of the best options for indoor usage. For starters, this type is more energy-efficient and long-lasting compared to incandescent. You would also be less worried about the heat they produce, and you can choose from sizes and shapes suitable for a small greenhouse.
Fluorescent bulbs give off blue light, but there are also full-spectrum lights, ideal for growing light.
You can differentiate high-intensity discharge lights into high-pressure sodium and metal halide, making the best auxiliary lights. High-pressure sodium lights emit red, which is best for budding and flowering. On the other hand, metal halide is a blue-coloured light that is useful to encourage growth.
These lights are also energy-efficient and long-lived, but they are better for large-scale greenhouses than small ones. They have large fixtures, and it’s hard to find lights of this type in small wattage. Additionally, they emit heat, so positioning them in a small polytunnel is tricky.
The most comfortable and perhaps the top pick grow light in a small polytunnel is LED. Unlike the HID, LED lights are small, lightweight, and easy to install, making them ideal for a mini greenhouse. They are also long-lasting without the danger of heat, and you can choose from different spectrums.
How to use a grow light
After understanding the two crucial factors, you can easily use a grow light in a small polytunnel with confidence. Start by knowing when to use a grow light, which depends on your plants’ specific requirements. Afterwards, design the set-up for the grows lights to be at a safe distance from the plants.
In general, you can have the lights 5 feet away from the plant, but you can adjust this depending on the need of the specific species. To save time and effort, you can also install a switch for the grow lights. Some can utilise a timer, but others even allow connection to your phone.
Over time and as the plants grow, remember that repositioning the lights will be necessary. You might even need to change the spectrum and the duration of usage of the lights.
Light is a crucial factor for plants’ growth and health, so polytunnel growers in the UK must provide the optimal lighting conditions indoors. You can quickly learn how to use a grow light in a small polytunnel or any polytunnel in that matter by considering the colour and type of light.
Once you understand the importance of spectrums and differences among light types, you can start with the grow lights’ set-up. Put them at a safe distance and adjust according to the requirements of the plant.