Do you need 1000W to grow indoors? Not with LED Habitats 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?

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.

Where the myth that you need 1000W to grow hemp comes from

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.

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. 

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.

How much wattage do you need to grow indoors?

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  (µmol). You need anywhere from 180 to 1300 µmol 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 µmol to grow up to 85% of their natural potential, or 1300 µmol to grow to 100% of their natural potential. Kitchen herbs, salads and other leave plants on the other hand only need 180-380 µmol.

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 grow light has an output that’s higher than 1300 µmol, 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.

Perfect amount of light
Too much light

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.  At the end of the day, you’re spending a lot of money only to produce 15% more yield!

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 light 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 spectrum light engine covers 420-660nm, allowing you to grow indoors using as little as 25 watts.

Here’s a breakdown of the best LED grow lights to use, depending on what kind of output you’re looking for:

  • Four-plant personal grow: You’ll need light coverage for four plants of about 4’x4′. You have a couple of options:
    • Two LED Root Max Lights, which provide an average of 577 µmol each at a distance of 3″ above the plants using just 103 watts each. This is an excellent option for vegetative or green plants.
    • Two LED Ditto Max Lights, which provide an average ppfd of 849 µmol each at a distance of 6″ above the plants using just 193 watts each. This is a perfect option for flowering plants.


It’s time to keep up with the times

Continuing to use 1000 watt HID lights to grow weed will only cost you money on huge energy bills and ever increasing cooling and plant nutrient costs. If you really want to grow pot in a way that’s easy and energy efficient, it’s time to make the switch to low wattage LED grow lights. 

If we can offer one piece of advice, it’s this: forget about how many watts you need to grow weed. Instead, invest in LED grow lights with a quality, broad light spectrum, even and high PAR coverage, and effective ?mol output and you’ll see happier, healthier plants in no time.

Don’t just take our word for it. Join the conversation and see what LED Habitats grow light gardener users are saying on Instagram and Twitter

-Klaus Messerer