Although greenhouses can receive a certain amount of natural lighting, it is still necessary to provide supplemental lighting because depending solely on weather conditions can be risky, especially when there are schedules to adhere to. Additionally, greenhouses typically receive only 75-80% of the outdoor Daily Light Integral (DLI) for the plants inside. Selecting the appropriate greenhouse grow lights can be challenging, but don’t worry. Here are some important considerations to assist you in getting started.
What to Consider When Buying Greenhouse Grow Lights?
Shadow Effect
The shadow effect is a significant consideration when it comes to greenhouse lighting. Many people are inclined to overlook the significance of shading, but it can greatly impact productivity. Even the slightest fixtures can create shadows that affect plant growth and result in uneven light distribution. Therefore, it is beneficial to choose LED lights with smaller light per μmol of output. Among top-tier LED lights, the MokoLight fixture has shown an average of 30-40% less shaded area in terms of square inches.
Light Spectrum
Different light spectra have varying impacts on plant growth.
- UV light (10 to 400 nm) can potentially increase resistance to environmental stress, fungi, and pests, but its negative impact on plants is not well-documented, so it is not commonly used in greenhouses.
- Blue light (400 to 500 nm) benefits flowering, growth, and root development. It enhances chlorophyll absorption in plants when combined with other light wavelengths.
- Green light (500 to 600 nm) is not extensively absorbed by plants and is typically not used alone. However, it can aid photosynthesis in lower leaves.
- Red light (600 to 700 nm) is widely used in grow lighting. It stimulates photosynthesis, promotes plant growth, and is often combined with blue light. Using only red light can result in lanky, stretched-out plants without the desired bushy effect.
- Far-red light (700 to 850 nm) is believed to promote flowering and increase leaf expansion, which enhances the plant’s surface area for photosynthesis. Like red light, far-red light should not be used on its own.
In greenhouse settings, the most common and frequently utilized light spectra are red and blue lights.
Types of Grow Lights
There are four types of grow light bulbs available for greenhouses, and the choice depends on the specific requirements of the space and plants. Let’s discuss each type:
- High-intensity discharge (HID) lights: These lights emit a significant amount of heat and need to be installed at a distance from the plants. They are suitable for larger greenhouses with multiple plants spread over a wide area.
- High-pressure sodium lights: This type of light produces a red spectrum that is ideal for promoting budding and flowering. It is a great option for greenhouse cultivation of fruits, vegetables, and flowers.
- Light-emitting diode (LED) lights: LED lights are highly cost-effective and have a long lifespan. They typically provide both red and blue spectra, making them versatile. LED lights are lightweight, easy to install, and offer substantial energy savings, up to 70% compared with other options. They have no warm-up time, are mercury-free, and are environmentally friendly for disposal.
- T-5 lights: T-5 lights are full-spectrum fluorescent lights known for their lower power consumption compared with traditional options. They emit blue light, which promotes robust plant growth.
Using grow lights, especially during winter months, is crucial for year-round gardening in greenhouses. Consider your budget and lighting requirements to determine the best grow light option for your greenhouse.
What Problems Can You Encounter with Greenhouse Grow Lights?
When purchasing grow lighting for your greenhouse, there are several benefits, but you may also encounter some problems. Here are a few issues to consider.
Insufficient Light
Insufficient lighting in your greenhouse can hinder the growth of your plants. Plants have a natural tendency to stretch towards sunlight, resulting in elongated and weak stems. This can lead to plants being top-heavy, susceptible to diseases, and failing to flower or bloom properly. To avoid this, ensure that your installed grow light systems have sufficient wattage for your plants. During the growth period, the lights should be positioned about 1 to 2 inches away from seedlings. Flowering houseplants generally require a distance of 12 inches from the light source for proper photosynthesis, while foliage plants can be placed 36 inches away. When growing vegetables, more light exposure is needed to stimulate flowering and fruit production.
Excessive Light
Too much light can be detrimental to plants in a greenhouse. Normally, plants require light and water to produce oxygen and starch. During the night, plants convert starch into sugar and store it.
Many greenhouse growers mistakenly keep the grow lights on constantly to promote faster plant growth. However, this can negatively impact the plant’s well-being. Excessive light exposure can lead to plant burn and paleness. It is crucial to provide plants with at least 8 hours of uninterrupted darkness to ensure optimal health.
When selecting grow lights, take into account the wattage and the distance between the light and the plants. High-wattage lights may be too intense for greenhouse plants and can harm their well-being. The lighting should not be positioned too close to prevent burning.
Plants differ in their need for light intensity. Plants that naturally thrive in dry areas with ample sunlight will need more light to flourish. On the other hand, plants that grow in shaded or tropical forests and have limited access to sunlight do not require as much light.
The Wrong Kind of Light
When selecting between high-intensity discharge (HID) lights and LED lights, it is important to consider the specific needs of your plants. HID lights may generate excessive heat, which can be too intense for smaller or weaker plants. LED grow lights offer versatility and a suitable light spectrum for various plants. Fluorescent grow lights are cost-efficient, cooler in temperature compared with other options, and can be a viable alternative.
Uneven Distribution
Proper installation of grow lights is essential for ensuring optimal growth of plants in a greenhouse, even if you have top-notch lights. Ideally, the recommended distribution is 20 to 40 watts per square foot of greenhouse space. To maximize the benefits of grow lights, make sure all parts of the plant gain sufficient light. Proper spacing of plants under the lights is crucial to prevent larger plants from overshadowing smaller ones.
The size of your greenhouse also determines the type of grow lighting you should buy. For larger greenhouses, High-Intensity Discharge (HID) lights are a suitable choice as they provide broader coverage. Fluorescent grow lights can also cover larger areas and generate less heat. It’s vital to install them evenly to ensure even coverage across the entire greenhouse. In the case of larger greenhouses, LED grow lights are another effective option.
How to Choose a Reliable Greenhouse Grow Lights Manufacturer?
If you encounter a grow light that promotes light quality based on lumens or lux, it should raise concerns. This indicates that the manufacturer lacks an understanding of the distinctions between lumens, lux, and PAR. Instead, focus on finding a company that provides accurate measurements and can even offer information about their testing procedures. A trustworthy LED grow light manufacturer will be able to explain the comprehensive technical details of their lights and engage in detailed discussions with you.
Look for information regarding PPFD, example lighting layouts, third-party trust certification, PAR photon efficiency (measured in micromoles per joule), and IP65 grade (indicating water and dust resistance). If a manufacturer includes such information, it shows that they possess a strong understanding of LED lighting technology and should be capable of answering your queries and addressing any concerns you may have.
A warranty is crucial as even well-made products can sometimes have factory defects. Other benefits like free consultations or discounted installation services can be advantageous as well.
About MokoLight
As an industry-leading LED light design manufacturer, We can help you select the best light for your greenhouse through free consulting. We also offer support services for LEDs to maximize performance for your plants. At MokoLight, the products are backed by reliable test data and come with a 3-year warranty. Contact us for the best greenhouse grow lights today!
