Every plant needs light to survive, cannabis included. The simplest way to provide plants with superb light is to place them outside, so they have access to the sun. Greenhouse gardens also provide a convenient way to take advantage of the sun’s rays without exposing plants to the natural elements.
While sunlight offers the best range of lightwaves during plant development, it’s not always possible for cannabis cultivators to grow outdoors. Not only is weed federally illegal, but many states also don’t have the best environment to grow cannabis. People who need the discretion and control of an indoor garden must find alternative ways to bring light indoors.
Finding The Best Grow Lights: Essential Tips When Setting Up Indoor Grow Lights
Thankfully, it’s getting easier to find countless indoor grow lights in various shapes and sizes. Indeed, there are so many grow lights that new cultivators are often confused over which product to buy. Anyone new to using indoor grow lights should consider the following tips when setting up their space.
LED Or HID? — What Grow Light Should Cannabis Growers Focus On?
There’s a lot of debate over which grow light is the ideal fit for indoor cannabis cultivation. However, most cultivators settle on one of two light models: light-emitting diode (LED) or high-intensity discharge (HID). Both of these light designs have a lot of merits, but most home cultivators will prefer LED grow lights.
Today’s LEDs have many noticeable cost advantages compared with HIDs. For instance, LED lights give off greater light intensity while drawing less power. LEDs don’t give off as much ambient heat as HIDs, which makes it easier for home growers to manage their tent’s temperature. Also, LEDs tend to last longer and require less maintenance than HID bulbs.
LED panels tend to be easier to fit into small grow areas, which could benefit those with limited space. LEDs with a dimmer switch may also be suitable for use during the seedling, vegetative, and flowering phases.
While HIDs aren’t a “bad” option, they come with unique considerations every homegrower needs to consider. Also, HIDs are far too intense during the delicate seedling phase. You will need to invest in fluorescent bulbs to help your seedlings grow and then switch to HIDs as plants enter vegetation.
Whether you rely on LED panels or HIDs, you need to measure your grow space and ensure the light model you’re working with will fit your tent. Double-check the weight requirements on your tent’s support frames and consider additional weight-bearing equipment like heat exhaust fans and ventilation. After you evaluate all of these considerations, you should be in an excellent position to pick a light suitable for your grow space.
How High Should You Hang Grow Lights?
There’s no set height where you should set the grow lights in your cannabis grow tent. Every grow light has a different average intensity, and your plant can only handle a certain amount of light at different stages of growth. Therefore, finding the perfect light placement for your cannabis strain will involve balancing multiple factors.
Most grow lights will come with a list of the manufacturer’s recommended hanging heights. Often, you’ll see average light intensities with measurements in “PPFD” when looking at these sheets. PPFD is short for “photosynthetic photon flux density,” and it refers to the available light that your plants can absorb for photosynthesis. Therefore, evaluating your light’s PPFD score is the most scientific way to determine where to place it in your grow tent.
As a general rule, cannabis performs best with the following PPFD scores:
- Seedling: 100 – 300 µMol/m2/S
- Vegetative: 400 – 600 µMol/m2/S
- Flowering: 800 – 1,000 µMol/m2/S
You should hang your lights far enough to achieve these scores in the center of your cannabis plant. Ideally, cultivators should use a light intensity screener to double-check that the PPFD values a manufacturer lists match with what your light is giving off.
Warning Signs Your Lights Are Too Close To The Plants
Light may be essential for cannabis growth, but placing these grow lights too close to your plants will cause significant issues. For instance, you may notice the top fan leaves start to curl and turn brown if you have a case of “light burn.” If left unaddressed, light burn could cause your cannabis buds to turn albino white, which will destroy the trichomes in your strains.
Aside from “light burn,” cannabis plants may exhibit signs of “light stress” if the light intensity is too great. If this is the case, you may notice symptoms like stunted growth, yellowing & curling fan leaves, and brown specks. If you’re using a light that gives off extra ambient heat, you may also notice “heat exhaustion” or dehydration in your cannabis plants.
Just keep in mind that the signs of light burn sometimes mimic other issues like nutrient or pH imbalances. Always screen your growing medium’s pH level and evaluate your feeding schedule before diagnosing your plant with light problems. Once you’ve cleared these potential issues, consider adjusting your light intensity or placement.
For more details on causes for yellow cannabis leaves, be sure to check out this previous International High Life post.
How To Decrease Light Intensity When Space Is Limited?
Many home cultivators complain that they don’t have enough vertical space to fix issues like light burn. While there is an upper limit to how high you can place your grow light, there are techniques that can help you lower your light intensity without moving this unit.
For instance, many indoor cultivators use training techniques to encourage cannabis plants to grow laterally. If you don’t train a cannabis plant, it will grow straight up like a Christmas tree. However, employing simple strategies like bending cannabis branches, using a screen in ScrOG growing, or topping cannabis plants during vegetation will lower the total height of your strains.
Another potential solution is to only plant cannabis strains that have a reputation for bushy growth. Most often, indica strains and autoflowers aren’t as tall as sativas. For more details on how autoflowers grow, check out our complete “Guide to Autoflower Cannabis.”
Lastly, if space is a concern in your grow tent, you should focus on LED lights with a dimmer switch. Some lights will let you cut the intensity of your total PPFD in half simply by turning on this dimmer.
Is It Bad To Buy Lights With UV Or IR Wavelengths?
You may see many grow lights that claim to offer a “full spectrum” of light that includes ultraviolet (UV) and infrared radiation (IR). While these light intensities aren’t ideal for human health, they seem to affect plant development. More studies suggest including some UV and IR in a cannabis grow light could increase the quantity and intensity of flowering buds.
While UV and IR may not be essential for growing cannabis flowers, you don’t need to be afraid they will damage your crop. If anything, tiny traces of UV and IR may lead to more resilient plants.
Always Keep An Eye Out For Light Burn!
As a final warning, please frequently check your cannabis plants for light burn issues, especially if it’s your first time growing a new strain. It’s also a good idea to learn techniques like low-stress training and ScrOG to manage potential light issues. Training techniques will increase your yield and dramatically reduce the likelihood that your plants will suffer from light stress. When caught early enough, your cannabis plant can recover from light burn and yield a bountiful crop.This article provides step–by–step instructions on how to set up indoor grow lights, including choosing the right type of light, setting up the lighting system, and adjusting the lighting for healthy plant growth. With this guide, you‘ll be ready to start cultivating your own plants indoors in no time!