How to Increase Weed Yields With LED Grow Lights

Lighting is perhaps the most important part of your equipment when growing weed indoors. After all, it can mean the difference between huge yields and great buds and small, underwhelming ones. So it’s important that you use the right grow lights. But where should you start when you have a choice of many different types of lamps? LED lights have come a long way in recent years and have become increasingly popular. However, there are a few things you should know about these bulbs before you get them. For one thing, LED bulbs are incredibly versatile. This is also their greatest strength. However, there are also LED lights that do not benefit your cannabis plants. So read on quickly and find out what you need to know before you buy LED lights!

What are LED grow lights and why should you use them?

lED’ stands for ‘light-emitting diode’. This type of lighting is incredibly energy-efficient, can emit strong light for several years in a row and does not give off much heat. Because of the small size of each diode and the versatility of the technology, you can use LED bulbs for a variety of things. From Christmas tree lights to streetlights to full-spectrum grow lights; they are increasingly becoming an obvious choice. Some of the advantages of LED grow lights are:

  • Cheap to use
  • Stay cool
  • Full-spectrum lighting
  • Adjustable spectra, with just one bulb for the entire grow
  • Possibly stimulates the development of trichomes
  • Saves water (through less evaporation)
  • They hardly give off any heat. This allows you to place them closer to your cannabis plants, exposing them to more light.

Some disadvantages of LED grow lights are:

  • The light spectrum of poor quality LED lights is not suitable for marijuana plants
  • Difficult to judge whether a manufacturer produces good lamps
  • Lack of heat can be detrimental in the winter
  • Some claim that autoflowers sometimes stop flowering because of LED grow lights (more on this later)

Nevertheless, LED grow lights are a good option for indoor cannabis growing, especially considering the recent developments in LED lighting. That is, if you’re willing to look into it and invest in good grow lights!

What LED grow lights are best to buy?

By purchasing the right type of LED grow light you can be sure that your harvest will consist of buds covered in glistening trichomes. However, you need to know the wattage and light spectrum to make an informed choice. Animals tend to respond to lumens, or the brightness of light. Plants, on the other hand, respond to the frequency of light. Therefore, it is important to look at how a lamp performs in this area. Super-bright light with the wrong frequency will probably get you nowhere.

Different types of LED grow lights

There are three types of LED lights, each of which has its own advantages and disadvantages. Higher quality models produce significantly better results. So if you’re serious about your cannabis cultivation, it’s best to go for those. In addition, LED lights last for years, so you might as well invest in good ones if you’re already sure you’ll be growing for years to come.

Standard purple LED bulbs

These bulbs are the original LED bulbs. They consist of a combination of red and blue diodes that together emit purple light. The blue light supports the plant in the early stages of its life and the red light in the final stage. Some lamps have the same color throughout the entire culture. Others, on the other hand, allow you to tailor the light to the vegetative and flowering stages of your plants. These lamps are among the cheapest form of LED lighting and are of the worst quality. The mass production of these therefore has a great impact on their reliability. In addition, it is difficult to find out whether the light spectrum falls within the necessary frequencies.


COB lamps are among the best LED lighting. It is therefore not surprising that these lamps are also some of the most expensive. “COB” means “chip on board. These lamps are composed of a large number of small LED lamps that together emit a bright white light. This intense light passes well through the foliage and offers your plants a full light spectrum. Some lamps can be tuned for the growing and flowering stage, but most have only one setting that is sufficient for the entire grow. Some manufacturers combine COB LEDs into one fixture, allowing you to use them for a larger grow space as well.

Diffuse LED

This type of grow light consists of a large amount of smaller LED lights spread across a large panel. This lighting is tremendously energy efficient and provides your plants with a good light spectrum and good light intensity. Commercial cannabis growers therefore also often use this type of LED lamp. These lamps are available in different variants. For example, there are spider lamps. This type of lamp has long arms that hang downwards. In this way you can adjust your lighting even better to your weed cultivation and offer your plants the best light. As you might expect, these lamps are also relatively expensive.

What size should an LED grow light be?

The size of an LED lamp, or power output, should be proportional to the size of the grow. For a one square meter crop, a lamp of about 400-600W is ideal. As a general rule in the growing world one watt of light corresponds to a yield of 0.5 to 1 gram of weed. Of course the yield ultimately depends on more than just the light, but this is a great rule of thumb to figure out how many watts you should have.

Led lights with a veg/flowering switch

As we mentioned earlier, some LED lights have a switch to change from the vegetative phase to the flowering phase. This changes the spectrum from blue (veg) to red (bloom). This change corresponds to the frequency of the sun at varying times of the year. It is not entirely certain whether this is actually better compared to a grow light set to full-spectrum. Nevertheless, LED lights with a switch probably do consume less energy, since you can turn off the unnecessary frequencies. So if you’re aiming for a lower energy bill and want to think about the environment, this type of LED is a good choice!

How many LED bulbs do you need?

To find out, you need to think in terms of light coverage. Ideally the entire canopy should receive a fairly equal light intensity. Often one good grow light is sufficient for this. However, if you have a large space with many plants then a combination of a few large lamps or several small lamps might be better. It all depends on your space and setup. If you are using SOG or ScrOG training techniques, for example, you should adjust your LED setup accordingly.

Growing cannabis plants with LED grow lights

Using LED grow lights to grow weed is pretty easy. Especially if you use full spectrum bulbs or lights with a switch. To switch to LED, you don’t have to transform your entire growing space. Nevertheless there are some things you need to take into account at each stage of the life cycle of your cannabis plants.

Led lights and the seedling phase

During the seedling phase your cannabis plants are the most vulnerable and need the most care. If you use LED lights, you need to be careful not to expose your seedlings to too much light. If your lights have a dimming option, consider using it. If they don’t have that option, then you can choose to move them around a bit. However, always pay attention to the plants themselves as well. If they shoot up, for example, it is often a sign that they are not getting enough light. This causes them to stretch. If you do nothing about this, you run the risk of them falling over. If the grow light has a veg/flowering switch then set it to veg. This way your plants will receive light from the blue spectrum. This type promotes root development, which is crucial at this stage. Then switch to an 18/6 light cycle, or a 24/0 light cycle if you are growing autoflowers.

LED lights and the vegetative stage

The vegetative stage requires more or less the same setup as the seedling stage. The only difference is that your plants can tolerate a higher light intensity. However, still make sure they don’t burn! If this is the case then the upper leaves of your cannabis plants will curl and discolour. Should your plants suffer from this then hang the lamps a little higher. With the exception of increasing the light intensity you do not need to change anything else about the settings of your LED lights. As with the seedling phase the same applies here: if your plants grow spindly upwards then that is a signal that they want more light. Although cannabis plants always grow upwards, healthy cannabis plants also grow in width and get a bushy shape. The exception to this rule is some sativa strains. Regardless of the environment, these strains always seem to stretch out.

Led lights and the flowering phase

To switch to flowering, set your LED lights to flowering mode (red) if you have this option. A photoperiodic cannabis plant will only flower at a light cycle of 12/12. So if you don’t adjust your light settings to this, these plants will remain in the vegetative phase. Again, watch out for light burn and stretching cannabis plants, and keep the grow light at the right distance.

Can you grow autoflowering cannabis plants with LED lights?

It is indeed possible. In general, you can grow autoflowers just like photoperiodic plants just fine with LED grow lights. However, there are stories circulating about autoflowering cannabis plants that stopped flowering in the early flowering stage under LED lights. If this is true at all, it still sounds like something abnormal and not the normal course of events. In any case, these stories should not deter you from using LED lights when growing autoflowers.

How far should LED grow lights be from your cannabis plants?

To answer this, you need to know the strength of your lights and what stage of growth your cannabis plants are in. In combination with the manufacturer’s instructions you should now be able to make an excellent estimate of this. A big advantage of LED lights is that you can place them much closer to your weed plants without the risk of burning them. This means that you can expose them to much more light and possibly increase your yield! Try some out and pay close attention to your plants. Basically you should hang your grow lights as close to the canopy as possible without burning your cannabis plants. After the seedling phase you are welcome to try things out to find out what the best distance is, as long as you take action quickly when things start to go wrong!

Can LED lights burn cannabis plants?

Even though you can place LED lights much closer to your plants, your cannabis plants can still burn. The good news, however, is that this happens more gradually. So as long as you pay close attention, you can fix any problems before any real damage occurs. Because LED is cool, the top leaves don’t burn immediately if the lights are too close to your plants.

Are LED grow lights as good as HPS lights?

This is a perennial debate that may never have a definitive answer. Nonetheless, on the whole, we answer this question yes. HPS lights are certainly a golden oldie, and have been responsible for the best indoor weed for decades. Many indoor growers are therefore reluctant to replace them. But while they undoubtedly lead to large, high-quality harvests, they are also expensive to operate, hot and relatively heavy. LED grow lights, on the other hand, are cheap when it comes to use, consume little energy, are relatively light and stay cool. This makes them much more suitable for a home grow, as you don’t need to ventilate. However, the disadvantage of LED lights, unlike HPS lights, is that they have not yet been standardized. This makes it difficult to find out what kind of LED lamps you are getting. With HPS bulbs, on the other hand, you know exactly what you’re getting. These are the differences between LED and HPS when it comes to setup, but what about yields? HPS grow lights are incredibly intense and often allow you to reap great harvests quantitatively. LED grow lights, on the other hand, are less powerful and therefore result in slightly smaller yields. However, many growers do claim that the buds are of better quality in this regard. So, what do you go for? Quantity or quality?