Pros of HPS
HPS lights are more standardized among manufacturers, making it a bit easier to comparison shop.
HPS light setups have a cheaper initial start-up cost, but the price gap between comparable HPS and LED grow has become much smaller as LED grow light setups have become more and more affordable each year.
HPS bulbs provide an immense amount of raw light intensity so they can produce great yields, particularly when working with very large plants.
Cons of HPS
HPS lights use much more electricity to generate light than comparable LED grow light setups and are thus much less efficient.
HPS lights also generate a lot of heat, which often requires additional ventilation equipment to maintain a proper grow room temperature. If not dealt with accordingly, the added heat can make growing very difficult. This is especially challenging if your grow area is already prone to heat issues (growing in a hot attic, for example).
HPS grow bulbs diminish in intensity significantly over time and must be replaced regularly every 12-18 months resulting in additional operation costs.
Pros of LED Grow Lights
Today’s best LED grow lights can rival the production of HPS lights that use nearly twice the wattage, which adds up to great savings on the power bill.
LED grow lights run much cooler than HPS resulting in an obvious set of benefits for the indoor grower.
LED grow light units typically come as all-in-one fixtures, which are easier to work with in tight spaces. They can also be placed closer to plants in confined areas with very little risk of heat damage.
Cons of LED Grow Lights
LED Grow lights do have a higher upfront cost but have been shown to save in the long run thanks to a lower cost of operation.
LED Grow Lights are not as standardized across manufacturers quite yet, making comparison-shopping more difficult. Still, the LED grow light industry has come a long way and design practices are becoming more consistent.
LED Grow lights produce very little heat, which for many is an advantage. However, those growing with LED’s in colder indoor areas may need to supplement the extra heat an HID light such as an HPS or MH would produce.