The simple answer is: it’s not really about wattage.

Wattage is a measurement of electricity consumption, and while it’s helpful to know how much wattage your grow light uses (so you can make a more economical, energy-saving choice) it actually has nothing to do with the amount of energy your plants need to grow.

Instead of looking at how much wattage a grow light uses, it’s far more important to understand the grow light spectrum, which is measured in micromoles (?mol). You need anywhere from 180 to 1300 ?mol to grow plants with highest yielding led grow light, depending on how light hungry your plants are. The Cannabaceae family of plants are on the higher end of the spectrum: they need 800 ?mol to grow up to 85% of their natural potential, or 1300 ?mol to grow to 100% of their natural potential. Kitchen herbs,salads and other leave plants on the other hand only need 180-380 ?mol.

You can use a PAR meter to determine your grow light’s intensity in ?mol for light spectrum between 400-700 nanometers (nm) – in other words, for any light spectrum that’s suitable for growing plants.
Can you use too much light to grow indoors?
Yes. Much like a human sunburn, your plants can burn or bleach if you use too much light.

More wattage may mean more light output, but it also means more heat output, which can lead to burned plants. If your hydroponic grow lights has an output that’s higher than 1300 ?mol, your plants can go into what’s called photoinhibition, when plants start spending more energy on getting rid of excess light rather than growing to their fullest potential. As a result, you’ll be left with wilted, brown leaves and dying plants.
Some growers counteract this by feeding their plants with more nutrients and introducing carbon dioxide into their grow spaces. This is a costly way to grow indoors. Not only are you introducing the costs of CO2 and added nutrients, but a 1300 μmol grow light also needs almost double the amount of energy as an 800 μmol grow light. You would also need additional cooling systems to get rid of extra heat to prevent your grow room from overheating.
What lights should I use to grow indoors instead?
With a good light spectrum, you can grow anything using much lower wattage, saving you energy and costs while yielding healthier, bigger plants. LED grow lights still aren’t widely understood among growers, but this new technology is the best way to get happier, denser plants. They use a lower wattage without sacrificing a quality light spectrum, so you can lower your LED lights right down to the plant canopy, giving them the weed grow lights they need without having to stretch out. While old school HID light alternatives, like HPS and CMH technology, have a lower initial investment, they need to be replaced frequently and require expensive HVAC cooling systems. A quality LED grow light, on the other hand, can last up to 10 years – and never requires a cooling fan. The grow lights in LED Habitat’s grow light gardens use a broad spectrum of light (including red, blue, white and green lights, not only red and blue or burple lights) to help you grow the densest, greenest and healthiest medicinal plants. Our broad grow lights for indoor plants engine covers 420-660nm, allowing you to grow indoors using as little as 25 watts.