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Just How Much Light is too Much Light?

Lately, we can’t stop hearing about LED lights, or a type of grow light which has been NASA tested for plant growth in space. Grow lights are also popular here, on earth, especially for growers who want to get a jump start on their spring season.

Grow lights are artificial lights which emit an electromagnetic spectrum for photosynthesis in plants. The bulbs come in various forms such as metal halide, fluorescent, incandescent, high pressure sodium and LED lights. These artificial bulbs give off different waves of light, similar to the sun, mostly ranging from blue to red and orange lights.

Grow lights not only give off different waves of light but can also generate heat. This is ideal for indoor growers who can’t grow during the winter because the sunlight isn’t strong enough to support plant life. According to the inverse square law, objects twice as far away receive a quarter amount of light. As a result, some indoor growers use reflectors to utilize the light and temperature while also growing their plants as closely as possible.

edited grow lights

Typically greenhouse growers will begin germinating their seeds, under grow lights,  a few weeks before the warmer weather. Seed germination is defined as the growth of an embryonic plant contained within a seed, resulting in the formation of a seedling. Seed germination can last a number of weeks depending on the age and type of seed. Once the seedlings are old enough to handle the outdoor conditions, they are transplanted into a low or high tunnel. 

There's been some debate about whether indoor growers need to expose their seeds to light and heat, at all times, in order to spark seed germination.

Seed germination requires water, oxygen, and certain amounts of light and temperature. Many gardeners believe keeping your seeds in a warm and dark place, by burying them into the ground, will ensure higher chances of germination. According to, however, there have been two major university studies contradicting this popular argument.

In 2006, researches at the University of Minnesota examined the effects of light on the germination of a variety of native sedge species. The study indicated that if the sedges were not germinated and established, before other plants leafed over them, they would most likely fail to germinate.

Another study at Iowa State University examined the effect of light on the germination of seeds of three varieties of Echinacea, an important commercial crop for organic growers in the herbal medicine industry. They determined that growers could overcome germination resistance by exposing their seeds to light, around the clock, in a cold, moist environment. The argument also aligns with nature, as most trees drop their seeds onto the ground; scattering them above the soil. 

What do you believe when it comes to exposing your seeds to light and warm temperatures? Do you use a grow light to jump start your growing season? Leave us a comment, we’re curious about your experiences!

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