Determine the size of your growing area.

Consider the amount of space your plants need and fill that area with light.  You can’t have too much light in your indoor garden (especially HPS light), however, you can have too much heat. As such, we recommend venting your light.

Metal Halide (MH)

If it’s mostly vegetative growth you’re after, metal halide lighting is the type of HID lighting you need. Similar to the sun’s rays in spring and summer, metal halide lamps produce light which is mostly in the blue range of the light spectrum, that’s what you need to grow lettuce, basil, and other leafy greens.

Determine what kind of light you need.

For vegetative growth, metal halide (MH) provides the most energy to your plants. For fruiting and flowering, high-pressure sodium (HPS) is the best choice. Once you decide, choose the correct high intensity discharge (HID) ballast to power your lamp.  Magnetic models like the Sunleaves Pulsar and Luma 2.0 ballasts run either MH or HPS lamps, or you can select a two-way model which allows you to switch between MH and HPS capabilities. Advanced electronic ballasts like the Future Brites can ignite both types of HID lamps.

High-Pressure Sodium (HPS)

If you want to encourage your plants to fruit or flower indoors, you’ll want to use a high pressure sodium lamp. By emitting light from the red-orange region of the spectrum, this sort of HID lighting simulates the sun’s light in fall. Plants under a high pressure sodium light think it’s time to finish their growing cycles so they make flowers and fruit.

Determine the reflector style you prefer.

When choosing a reflector consider the area you would like to cover and the required light intensity of the plants you’re growing. Keep in mind that a deep reflector will concentrate the light source on your garden below. A shallow reflector will disperse light over a wider area but it will be less intense where it falls. Choose a system with vents and a tempered glass lens to eliminate heat build-up in your garden room. A lens also protects the lamp from dust and water.

Conversion Lamps

If you don’t have a switchable or electronic ballast, choose a conversion lamp. This allows you to burn an HPS lamp with an MH ballast and vice-versa. Because the conversion process itself takes some energy to accomplish, conversion bulbs aren’t quite as efficient as regular metal halide or high pressure sodium bulbs, but they will give you the best of both worlds with just one light system.

Choose the correct lamp.

No matter what type of ballast you select, the lamp wattage must match that of the ballast (i.e.400W ballasts = 400W lamp). And remember, unless you purchase a two-way model or an electronic ballast (like a Future Brite), you cannot use a MH lamp in a HPS system or vice versa. To get HPS light from a MH system (or vice versa), choose a conversion lamp of the appropriate wattage.

HID Lamp Burning Position

Burning positions for all HPS and conversion lamps are universal “U”. MH lamps designated “H” must be used in a horizontal position, lamps designated “BU” must be used base up (vertically).