Yes. Much like a human sunburn, your plants can burn or bleach if you use too much light.
The main problem with HPS lights (and other high-intensity discharge / HID lights) is that they end up wasting up to 60% of the energy they consume solely on heat output. In other words, if you’re using a 1000W HPS light to grow indoors, only 400W of that energy is being used for plant growth – the other 600W is being wasted, draining money from your pocket.
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 grow lights, 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.
The idea that we need 1000 watts to grow hemp comes from the days when it was common to use High Pressure Sodium (HPS) lights to grow anything indoors. At the time, HPS lights were the only decent artificial light source on the market, and a 1000 watt light was necessary for a sufficient photosynthetic light spectrum.
How much wattage do you need to grow indoors?
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.
Let’s take a look at this short day plants-growing myth, and how you can grow indoors with eco-friendly (and wallet-friendly) LED grow lights.
A lot of people believe that you need a 1000 watt artificial light to grow hemp indoors. The reality is, you can successfully grow medicinal herbs with far less wattage, saving you money on your electricity bill while growing healthier plants. So, how much wattage do you really need to grow indoors?
Do you need 1000W to grow indoors? Not with LED Habitats Grow Lights
The simple answer is: it’s not really about wattage.
Those 400W are also giving you a fairly narrow grow light spectrum, so your plants end up not getting the amount of proper light they need.
The easiest way to think of them is to consider the 315w bulb equivalent to 600w of MH or HPS light and the 630 watt dual bulb fixtures equivalent to 1000 watts.
Plants will do fine with less than that, but those are the numbers to shoot for if you want to optimize yields.
Scroll down and find the type of type of lighting you plan to use below. Then follow the instructions to figure out the size of light you need and how many lights you need, if more than one.
Using The Wattage
This contrasts with another light measurement lumen, which measures the amount for light that is visible to the human eye.