Lighting Types and Light Coverage

Using a grow light is a great way to extend your growing season. You should consider a grow light if you want to grow vegetables or fruit plants in the winter. There are several types of grow lights available, each produce different types of light that will benefit your plants in different ways at different stages of plant life.

T-5 Fluorescent Grow Lights

Use less energy and provide a more intense light than standard fluorescent. T-5 full spectrum lamps are better than fluorescent lamps because they are thinner, lighter and more efficient, and capable of producing greater intensity. T-5 lights can be placed close to the top of your plants since they do not produce much heat.


Metal Halide Grow Lights

MH emit the violet and blue portions of the sun’s light spectrum. This is the kind of light that is found during springtime. MH lights help the plants develop a compact green growth and a stronger root system which will help them be more disease resistant. MH light is best for starting plants and supporting them while they are in early stage of life. They do produce some heat and you will want to keep at least 24 inches between the lamp and top of the plant.

High-Pressure Sodium Lights

HPS Lamps produce more of the orange and red spectrum. This light spectrum naturally occurs during late summer and fall. HPS encourage flower production, bulking and ripening of fruits and flowers. HPS light is best for flowering stage. HPS lamps do produce heat and will need to be placed 2 to 4 feet above the tops of your plants.


The wattage of the light will determine how much light coverage you will get. Manufacture specifications recommend -
1000 watt lamp to cover 7' x 7' area
600 watt lamp 6' x 6' area
400 watt lamp 4x4 area
250 watt lamp 3' x 3'
For better results and maximum yield you will want to increase the available light and use the following recommendation -
1000 watt lamp to cover a 4' x 4' area
600 watt lamp for 3' x 3' area
400 watt lamp for 2' x 2' area
250 watt system for 1' x 1' area
To calculate your monthly electric cost, multiply bulb watt times the number hours operational and divide by 1000. This will give you the Kilowatt Hours used - Example 400 watt bulb 18 hours a day would be 7.2 kilowatts. Check your bill for the cost of each Kilowatt-hour. Then multiply the number of kilowatt-hours used by the cost of a kilowatt-hour (K/hr) to figure the cost to run your light.
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