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How Far Should You Place Your Light Above Plants?

As a general rule of thumb, most outdoor vegetables and flowering plants need 12 to 16 hours of light per day to thrive, with flowering plants at the top end of that range. Dark is also important for the plant growth cycle - plan on giving most plants at least 8 hours of darkness per day. But remember that different types of plants may need different amounts of light.

Houseplants are popular indoor decorations. Attractive and constantly changing, they add a softness of line and provide a bit of nature indoors. However, the ideal location of a plant for decoration may not be the ideal spot for plant growth. Lack of adequate light is the most common factor limiting the growth of plants in many areas of the home.

Houseplants with artificial lighting - LED light

That's why adding supplementary electric lighting is so commonly used for both indoor and outdoor plants and usually the easiest and least expensive way to provide enough light for plants that do not receive adequate natural light.


When determining the height to place supplementary lights, it is first important to learn what PPFD means. PPFD stands for “Photosynthetic Photon Flux Density” which is the amount of light that is able to reach the plant and be absorbed to carry out photosynthesis. It normally refers to the visible light spectrum of 400-700 nm.

When the lamps are put closer to the plants, the light intensity increases and therefore also increases the PPFD. Different plants require a different value of PPFD for an optimum growth rate, which should be checked and confirmed beforehand. This can range from 50-800 units, while it normally falls between the range of 200-400 units.


Average PPFD

Light Time

Low-Medium Light Plants (Orchids, Microgreens, Herbs, Ferns, Ivy)


12 hours

High Light Plants (Succulents, Monstera, Ficus)


12 hours

Leafy Greens (Lettuce, Spinach, Arugula, Kale, Cabbage)


8 hours

Fruiting Vegetables (Tomatoes, Peppers, Eggplant)


8 hours

After discovering the PPFD requirement of your plants, check the light intensity that can be supplied by the lamps. Take the PPFD chart of the OmniPV Solar Garden LED Grow Light (Universal Version) as an example, we can notice the PPFD can reach over 200 units if it is put at 40 cm above the plants.

PPFD for Solar Garden LED Grow Light (Universal Version)
PPFD for Solar Garden LED Grow Light (Universal Version)

When it comes to the Floral Version of the OmniPV Solar Garden LED Grow Light, since the lighting angle is different from that of the Universal Version (60° vs 90° respectively), the PPFD values will be different too. For the same PPFD value to be obtained, it can be placed at 70 cm above the plant to get the same light intensity (or 2.5x stronger light intensity when put at 40 cm above the plants).

PPFD for Solar Garden LED Grow Light (Floral Version)
PPFD for Solar Garden LED Grow Light (Floral Version)

Depending on the light source used, the lamp may give out a significant amount of heat, which evaporates the water content of leaves and can even burn the plant. The OmniPV Solar Garden LED Grow Lights adopted LED technology and can be put as close as 20 cm above the plants.

While those numbers above give you a rough idea of how far the lamps should be put above the plants, users still need to observe the condition of the plants being shined by supplemental lighting to see if the lamps are put too close to the plants. Some of the indicators are: irregular growth of the leaves, curly or soft leaves, bleaching of leaves (white or yellow spots), and browning of leaves.

Still confused? Feel free to contact us and our specialist will be more than happy to assist you with the full set of solution.

“OmniPV is a team of clean energy enthusiasts who has a strong commitment to provide the best service and high-quality products to our customers”

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