Indoor growing has opened the door for many possibilities for cultivators around the world to grow year-round, regardless of the region or climate conditions. Lighting is arguably the most critical component of indoor cultivation and is often misunderstood by novice indoor growers. Poor lighting choices or setups can make or break a harvest, but not to worry, we have created the perfect guide for indoor growers starting their journey! 

Whether you’re growing leafy greens, herbs, or cannabis, avoiding these common mistakes will help you get the most out of your LED grow lights and boost plant performance from seed to success. This guide is designed specifically for indoor growers who want to improve their yields and avoid common mistakes.

1. Using the Wrong Spectrum: A Common Mistake for Indoor Growers 

Plants need different spectrums of light depending on their growth stage, crop species, and crop variety. Many new indoor growers rely on cheap fixtures with limited spectrums, leading to stretched plants, poor root development, or low yields. With the growing popularity of LED lighting and its advancements, the capability to fine-tune a light spectrum has never been greater.  

Among the treatments, far-red light resulted in the highest productivity increase of around 15–20%, although the results varied greatly across different studies, as shown by the large error bar. This is likely because far-red light has been shown to boost biomass production during the flowering stage, contributing to higher yields in many crops. Blue light and the combination of red and blue light (Red:Blue) both showed similar productivity increases, averaging around 8-10%, but with moderate variability in results. Blue light, in particular, is well known for promoting strong root development and compact, vigorous vegetative growth, which explains its consistent productivity benefits across a wide range of crops. Green and red light treatments showed smaller gains, with productivity increases of around 5–7%, and generally smaller error bars, suggesting more consistent results across experiments. Overall, while far-red light shows the greatest potential to boost productivity, blue and red-blue light treatments also provide notable benefits, making them common choices in controlled environment agriculture. Understanding spectrum is essential for indoor growers looking to optimize both vegetative and flowering phases. 

2. Inconsistent Light Schedules

Plants thrive on consistency. Skipping light cycles or forgetting to adjust for the vegetative or flowering phase can stunt growth or cause plants to stress. Use timers and be mindful of your crop’s photoperiod needs, typically 18/6 for veg and 12/12 for flower. Indoor growers often underestimate the importance of consistency but it’s a crucial factor in long-term success.

3. Hanging Lights Too Close or Too Far

Light intensity matters, and placement is everything. Hanging your lights too close can cause bleaching or burn, while too far will lead to stretching and weak growth. Check the manufacturer’s recommended hanging height and regularly measure PPFD (Photosynthetic Photon Flux Density) at canopy level. 


4. Ignoring Light Uniformity

Hot spots and shadows can seriously impact your yields. Uneven light distribution often leads to inconsistent growth across your canopy, with some plants thriving while others struggle. To avoid this, choose lighting setups designed for even coverage throughout your space. You can also consider adding under-canopy lighting to boost lower growth, maximize yields, and reduce wasted energy in your grow room. 

5. Underestimating DLI (Daily Light Integral)

Many beginners focus on hours of light but overlook the total quantity of usable light their plants receive in a day. DLI measures how much light plants get over 24 hours, and it’s crucial for healthy growth. Too little, and your plants won’t photosynthesize effectively; too much, and you risk stressing them, all depending on your crops needs. It’s also important to note that some light spectra interact with DLI. For example, far-red light can influence flowering speed depending on DLI levels, promoting faster flowering at low DLI but having less of an effect at higher DLI. However, adding blue light may offset some of far-red’s effects on plant morphology, such as excessive stretching, without changing flowering time. Understanding both DLI and spectral interactions helps you fine-tune your lighting for optimal results. 

6. Skipping Environmental Balance: Why Indoor Growers Must Prioritize Climate Control

Lighting affects more than just plant growth, it also impacts heat, humidity, and transpiration. Failing to account for these interactions can create the wrong environment in your grow room. A balanced grow space considers light intensity, airflow, CO₂ levels, and temperature holistically. Using a CO₂ regulator and controller setup can help maximize yields and speed up growth. Research also shows that your choice of lighting plays a role in temperature control. LEDs, for example, generate less heat compared to fluorescent lamps, resulting in smaller increases in both the environment and microenvironment around your plants, making it easier to maintain ideal conditions.


7. Choosing Cheap or Unreliable Fixtures

Inexpensive lights might seem like a smart move at first, but poor diode quality, limited spectrum, high failure rates, and low energy efficiency will cost more long term. Invest in proven, commercial-grade LED grow lights built to support your crops, not compromise them. 


8. Not Upgrading When the Canopy Grows

As plants grow, their light needs change. A mistake many indoor growers make is not adjusting light position or intensity as the canopy thickens. Taller plants may shade others or block light from reaching lower foliage. Periodic adjustments to height, spectrum and intensity may be required to ensure even growth and healthy development from seedling to flowering crop. 


9. Overlighting Small or Sensitive Plants

Yes, too much light is possible. Seedlings, clones and microgreens can easily become stressed or damaged under high-intensity lighting. Start with lower intensities and increase gradually, allowing the plant to adapt and develop a stronger foundation. 


10. Neglecting Maintenance and Monitoring

Grow lights aren’t the “set it and forget it” type. Regularly inspect your fixtures and monitor plant behaviour. If something seems off in growth patterns, lighting may be one of many issues involved. In addition, it is incredibly important to keep your growing space clean, especially if you are cultivating in a commercial setting. The cleaner it is the less risk you have within your environment. Having unclean cannabis cultivation can create dangers like waterborne pathogens and bacteria growth. Plants also involve an incredible amount of detailed care, including pruning, topping and spacing.