Can You Grow Autoflowers with LEDs

LEDs have come a long way since they were first introduced. A technology once considered low-tech is now praised by indoor growers all over. But, can you grow autoflowers with LEDs? Find out how, in this article.
Author Netra Manjunath
01 December 2018
8 min read
Can You Grow Autoflowers with LEDs


Autoflowers are easy to grow, despite what you’ve been told. They adjust to any growing condition as long as it isn’t extreme. Similarly, they will grow no matter what light you use, but obviously, stronger lights equate to stronger plants and higher yields.

Even as a beginner, you’ve probably heard of LEDs. LEDs were introduced just a few years ago, and growers wouldn’t even consider growing marijuana plants because they weren’t as good as other high-intensity lights in the market. However, just like people changed their minds regarding autoflowers, LEDs managed to turn around and produce great yields.

Now, most growers grow only using LED lights and it’s pretty common to use them for an entire grow cycle. Growers preferred HIDs or HPS (High-Pressure Sodium) lights until LEDs overtook every other light including CFLs and MH lights.

As you can imagine, there are various lights that can be used, but why LEDs? What makes them so special for growers to switch to them especially considering hefty sums of money invested in HIDs? Well, it’s pretty simple. LEDs are easy to maintain. And the plants love them too. As a grower, it’s your responsibility to provide everything the plant needs, and LEDs are no exception. So, let’s take a look at whether you can grow autoflowers with LEDs.

What are LED Lights?

LEDs – Light Emitting Diodes – are lights that can be used to grow almost any type of plant. Technically speaking, it contains two semiconductors – electrons and holes. While electrons are negatively charged, the holes are positive. When an electric current is applied over the light, the two semiconductors collide with each other and release energy, otherwise known as photons.

This entire process is known as recombination. The LEDs introduced at the very beginning weren’t of any advantage to a grower since the light output was meager compared to other lights; however, with technology and years of research, many manufacturers now produce outstanding LEDs that almost mimic the sun’s full spectrum.

Why use LEDs?

When compared to HIDs, LEDs are a tad more expensive. Then why choose them? Well, LEDs may be a little more expensive than HPS or HID lights when you first purchase them, but the costs reduce in the long term, making LEDs certainly cheaper than maintaining HPS lights.

And that’s because HPS lights need to be replaced often. Either the filament burns out or you need to replace the entire set. Most importantly, HPS lights draw a lot of power that leads to hefty electricity bills. Of course, HPS lights work wonderfully when you want dense, tight nugs, and one can’t completely write it off, but LEDs have a distinct edge over them.

Also, LEDs aren’t fragile; in fact, they are robust with no delicate parts that make less susceptible to burnouts or damage. Another major advantage that comes with LEDs is the fact that the lights mimic natural sunlight as much as possible.

Cannabis is a wild plant that grows like a weed. They have a natural tendency to produce resinous colas covered with trichomes. When they receive sunlight, they grow to the best of their potential. But indoors growers need to provide light very similar to sunlight. And, let’s face it – no light can produce a complete spectrum like the sun.

However, LEDs come very close. Since LEDs give out blue and red colors that are very essential for the development of buds, they work as great substitutes for sunlight. A variety of additives can be added to the diodes used in manufacturing the lights and this very ability allows them to illuminate photons in several colors.

In other words, LEDs have a full spectrum with colors meant for different stages of the plant. It mimics the change of seasons, thereby tricking the plant into thinking that it’s sunlight. Thanks to such an advanced technology, it’s no wonder that LEDs are emerging as the frontrunners in the market.

What are the disadvantages of LED lights?

You get the complete picture only when you understand the pros and cons of a particular product. Light equates to food for cannabis plants, and it’s extremely important for autoflowering plants that have a short lifespan. And now that you know why LEDs are so awesome, you might be interested to know the disadvantages as well.

  • Expensive

As mentioned already, the cost of LEDs is a bit more than other lights such as fluorescents, HPS, and MH lights. However, the LEDs that are being introduced now are so competitive that they cost as much as HIDs.

The manufacturing market is saturated with too many LED manufacturers and it is indeed possible to purchase cheap lights. But, if you love big, thick buds then you have to go for the ones manufactured by brands that are a bit expensive.

  • Not all companies provide a full spectrum

Most companies provide a full spectrum of light; however, it’s recommended that you do your research before purchasing lights because some companies aren’t very technologically advanced yet. If you do purchase an LED, make sure that it comes with all the colors required for your lovely autoflowering cannabis plants to grow.

Can you grow autoflowers with LEDs?

Yes, of course, you can! In fact, you can grow any type of plant using LEDs without any issues. They last for a long, long time with some lights continuing for more than 50,000 to 100,000 hours!

Here’s a quick example of how your autoflowers might fare under LED lights:

How to grow autoflowers with LEDs?

A major advantage of using LEDs is that you don’t have to change the light to match the stages of the plant. For instance, the plant needs a lot of blue light in the vegetative phase. In such stages, growers use MH lights and switch to HPS lights during flowering. Even if you use CFLs, “Cool Blue Daylight” lights are used specifically in the growing phase.

Since LEDs contain all the colors, there’s no need to switch the lights between phases. But, remember that this is true only with certain lights because LEDs being introduced now come with separate vegetative and flowering switches. No, you don’t have to switch to a different light, but you may have to manually control the switches.

Things to keep in mind when growing autoflowers with LEDs

  • Distance between the light and plant

Growing seedlings with LEDs can be a little tricky. Seedlings are very fragile, and if the lights are too close, they tend to burn. Conversely, they grow tall and lanky if the lights are far away. So, the trick is to maintain the perfect distance between the plant and the light.

This is why many growers use T5 fluorescent lights, CFLs and MH lights to tend to seedlings. However, if you plan to use LEDs for the entire cycle, you need to be very careful at the beginning. For starters, read the manufacturer’s instructions carefully.

Most lights are placed at a distance of at least 18-22 inches away from seedlings, and you can do that too. Once you observe how the plants react, you’ll be able to judge the distance yourself. Autoflower seedlings need to be observed much more because the plants can get stunted if the tender leaves get burnt.

  • Heat

Autoflowers have a lot of growing to do and they do it very fast. So fast that you’ll be on your toes to keep up with it. If you want the very best yields, you must be prepared to work for it. And talking about maintaining the plants, heat plays a major role.

Autoflowering cannabis plants thrive in environments where the temperature is neither too cold nor hot. If the temps exceed 35°C, the yields diminish quickly and the buds begin to burn too. Similarly, they cannot stand temperatures that go below 15°C.

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Fortunately, you can play God when growing indoors and control the temperatures. But, it becomes easier if you plan it well. For instance, some lights like HIDs emit a lot of heat and the temperatures soar pretty quickly.

Even some LEDs exhibit similar tendencies and produce too much heat. Therefore, make your life easier by purchasing lights with inbuilt fans to reduce the heat.

  • Use lights with better features

LEDs offer so many features that it can be mind-boggling. From dimming to power efficiency to a full spectrum, they appear to be the perfect companion to your autoflowering plants. However, while some companies offer all the features, they come with a price tag.

If you’re really interested in quality yields, though, look for lights that offer ‘dimming’ features. Some lights come with knobs that can be used to adjust the brightness of the light. For example, plants need more light during the vegetative phase and the lights can be dimmed during the flowering phase to save energy and money. However, if you absolutely cannot afford such lights, it’s still okay because the plants will grow even if you don’t dim the lights.

  • Research, research, and more research

The only way to grow excellent plants is by choosing great lights. And you need to do a lot of research to buy lights that suit your setup. LEDs are available in various sizes and watts, and the differences in costs and features can be jaw-dropping. For instance, a branded 300W light can cost anywhere from $80 to $100, but bigger brands offer the same at $350.

If you dig a little further, you’ll be surprised – nay, shocked – to find out that some brands offer 1000W lights for just $70! Amazing, eh? Obviously, there are differences in how the lights perform, and it’s up to you to figure out what your plants truly need.


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