What are HID Grow Lights?

HID stands for High Intensity Discharge. High Pressure Sodium (HPS) and Metal Halide (MH) are two types of HID bulbs that are good for indoor growing. MH bulbs produce light in the blue spectrum. This light is better for plant growth during the vegetative stage as it promotes stem, branch and leaf growth . HPS bulbs produce light in the orange to red spectrum. The light produced in the orange to red spectrum triggers the release of plant hormones used in the flowering stages. You can usually expect higher yields when growing with HPS bulbs.

High Pressure Sodium (left) and Metal Halide (right) Grow Light Bulbs

High Pressure Sodium (HPS) Grow Lights

Advantages:

Longer lasting

Higer yields

Better for flower or all around growth

Disadvantages:

Higer energy costs

Produce more heat

Metal Halide (MH) Grow Lights

Advantages:

Cost efficient

Better for vegetative growth

Better for smaller crops

Disadvantages:

Shorter life span

Lower yield