Cannabis Guide: LED Wattage Chart When Growing Weed Autoflowering

growing weed autoflowering

Growing Weed Autoflowering is becoming an increasingly popular hobby, but with it come some roadblocks that a beginner must bust through. It’s not an easy job, and it requires proper research and preparation if you want to see significant results on your weed autoflowering.

This is where I come in. I’ve prepared all the info you need to successfully choose the best LED grow lights, including why you’d choose them over other similar products, how it all works, and more. After reading this article, hopefully, you’ll be prepared to tackle the world of cannabis growing smartly and efficiently!

Weed Autoflowering LED Wattage Chart

No. of PlantsSquare FeetWattage
Wattage assuming 1.0 sq ft/plant
Wattage assuming 2.0 sq ft/plant
Wattage assuming 4.0 sq ft/plant

Here’s a comparison table for LED lights versus a variety of other options, in several categories:

CostAll Over the PlaceMediumMediumMedium-HighLow
Heat OutputVery LowHighHighHighLow
Lifespan50000 Hours15000 Hours15000 Hours20000 Hours10000 Hours
Supporting tools requiredNoneBallast + ReflectorBallast + ReflectorBallastBallast
Application (best for which stages of grow cycle)All StagesFlowering StageVegetative StageAll StagesVegetative Stage

Calculating Your Ideal LED Grow Light Wattage

Knowing how much power and space you need for your growing weed autoflowering is very important when you’re raising anything in-doors. However, it can also be difficult to determine while snake-oil salesmen are trying to sweet-talk you into buying whatever they can pitch, with false promises and withheld information. This has been certified by BigMike or also known as Michael Straumietis in his online efforts as a marijuana influencer.

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It’s a simple calculation! The total wattage you need depends on how much space a single plant needs and how many plants you have in your garden. A square foot of space typically requires about 32 Watts of LED power.

Multiply that by the number of plants you have and the average space one plant needs, and you have a rough estimate of the kind of power you want. But let me simplify it even further and just give you the values. For a square foot of cannabis space, you want 32 Watts. If you’re going for two sq ft, you want 128 Watts. Three sq ft requires 288, while four sq ft needs 512 Watts of juice.

800 Watts of power will keep you covered if your workspace is the commonly used average of 5 square feet. However, if your weed autoflowering plants are in their vegetation stage, remember to reduce the wattage by roughly 50%. Plants in this stage don’t need nearly as much light exposure as they do in the flowering stage, and leaving the full power on can have some mild negative effects.

Growing weed autoflowering also don’t need super-powerful lighting, so don’t go overboard. People typically recommend weaker CFL lights for this, since you can place them closer to the seeds to save space, but this becomes irrelevant later, so just do it the right way from the start.

Weed Autoflowering LED Grow Lights Q&A

How do LED lights work?

The light you see coming out of one of these diodes is created by the movement of electrons within the semiconductor material that goes into diode construction. This is different from a standard incandescent bulb in that there is no filament you can burn out, which would cause you to have to replace your LED.

This difference also keeps LEDs at lower temperatures, which is safer for plant growth. Most LEDs have a lifespan similar to that of a transistor, which is many, many times the lifespan of a traditional incandescent bulb. LEDs function well as long as they’re connected to an electrical circuit.

Problems and Solutions While Using LED Grow Lights to Grow Cannabis

The Temperature’s too High! What Do I Do?

While this is very unlikely (given how LEDs put out very little heat by themselves and a lot of panels come with built-in cooling fans), you want to examine the environment your cannabis is growing in. Where the heat could be coming from? Invest in a better cover if too much sun exposure is messing up your plans, or buy extra cooling fans to air out the heat.

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Even better, plan for these things before you even plant the cannabis (next time), to avoid potential mishaps. Consult customer support if you’re stuck, as they’ve certainly dealt with this type of issue before, and are there to help.

The Lights are Too Near to the Plants! Help!

Every panel has an ideal distance you want to maintain. If you don’t, nasty side-effects may occur, such as a change in the plant’s shape or color, or overall poor health. These are all bad enough to be avoided at all costs, so make sure your lights are farther away.

If you don’t have the necessary workspace to make this adjustment, work on expanding it as soon as possible, for your plants’ sake. If this is too inconvenient, consider purchasing lights that are safer at the distance you can work with, as a compromise. Anything is better than letting your plants just suffer in the incredibly intense light.

How Long do LED Grow Lights Last?

The good-quality panels will often clock in 50000 hours with next to no hiccups. This is almost 6 years of work, which is WAY more than you can expect from basic incandescent bulbs or any other kind of light used for growing weed autoflowering.

It is highly unlikely that your LEDs will become a fire risk at any point in their lifetime. The lights are designed to consume little power, emit next to no heat whatsoever and maintain a generally low temperature. Fires that start can sometimes be blamed on the equipment when the real issue was faulty wiring inside the wall or wherever.

If you want to minimize the risk of overheating, use a resistor when connecting LEDs or make sure they’re secured in a way that lets the heat leave the immediate area. As you may have learned by now, this is very easy to do, as LEDs practically help you out directly.

Are LEDs Too Hot for Wood Frames?

Simply put, no. While the warmer part of the LED is near the bottom, the diode’s overall heat efficiency doesn’t let it do much if any damage to a wooden surface, especially if placed in a way that prevents this. The same tips for preventing fires work here.

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Either use a resistor or check your wiring. Alternatively, improve your cooling system overall to minimize this risk further. Buying plastic-encased panels also completely remove any risk of wood being burned, so relax and stop worrying. The higher your panel quality, the more impossible this issue becomes.

Can I Use LED Lights in Combination with Other Lights?

Not only is this possible, but I would also strongly recommend it. Not all lights are equally good during all stages of a plant’s growth, so combining the best of both worlds is a surefire way to end up with healthy, gorgeous looking foliage and big juicy buds.

This is especially helpful if your workspace doesn’t allow you to place all your LED panels at an ideal distance since not following those specifications can at best result in inefficient lighting, and at worst – harm for the plant you’re growing. CFLs, in particular, can be a good variant to include since their ideal distance is very close to the plants.

Are LEDs Harmful to the Eyes?

During my product reviews, I mentioned that you want sunglasses for some of those models, so it’s safe to assume that you shouldn’t be staring at your diodes while they’re in use. The blue light emitted by every decent LED product can contribute to eye disease and has been known to disrupt sleep.

LEDs also lack the near-infra-red heat you get from the sun, so they’re less healthy overall than regular lights. Do not handle your LEDs without eye protection, seriously. They may be healthy for your plants, but they aren’t as gentle as humans.

Do LEDs Contain Hazardous Materials for Humans?

While LEDs don’t contain mercury like CFLs, that doesn’t mean they’re perfectly clean. There are some toxicity risks hidden inside, such as lead and arsenic. You’re not going to be in direct contact with any of that stuff, but it helps to know exactly what you’re dealing with.

Make sure none of your diodes are cracked, and thoroughly inspect the ones that stop working. LEDs are slowly becoming the #1 light of the future, and people should be aware of what kind of materials are being used. That way, health risks are minimal or nonexistent, and we can all safely grow whatever we want at home.


That was a doozy, wasn’t it? There is so much to know about growing weed autoflowering seeds, even when you specifically examine the lighting aspect of it. Not a hobby for the unmotivated, I’ll tell you that. Hopefully, I’ve managed to ease you into the world of home-growing, as there are a lot of rewards to be gained from this kind of activity. Be sure to let me know if you have any feedback, as I’d love to hear your stories and tricks! I’m also always here to help if you have questions, so don’t hesitate to ask if you have some concerns.

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