As indoor growing becomes more popular, new and experienced growers alike are all on the hunt to optimize their grow in every way possible to achieve the best yields, dankest buds, and most intense hard-hitting highs from the cannabis they grow.
BudSeed’s cultivation expert, BigJ is here to share some his knowledge about Cannabis grow lighting, and some tips and tricks of the trade that you can use to produce some fire Bud in your own grow.
Indoor Lights vs. Sunlight
Growing cannabis under the hot sun is how cultivars have grown for hundreds of years. So why spend the money and electricity to grow using artificial light?
The answer is control! With indoor lights you can control everything including intensity, duration, light spectrum, and more. When growing outdoors you are at the mercy of the Sun; cloudy, rainy, or whatever mother nature throws your way can have a significant impact on the final outcome of your harvest. When growing indoors, we can provide our cannabis plants with the perfect amount of light intensity, duration, and light spectrum at each stage of their growth to maximize yield and potency of the end product.
To get more out of a system, you must input more energy into it. A full spectrum LED light with IR and UV light penetrating deep into your entire Canopy 18 hours a day outshines even big old Mr. Sun.
Grow light Coverage
How many lights do I need per plant? Per square meter of Canopy? For a 4×4 tent? Common questions I hear growers new to Indoor growing asking.
The answer? Budseed recommends 320w – 500w of light per square meter, or about 30-50w per square foot.
The number of plants you have in that area does not matter, whether running a Sea of Green growing technique, or a single plant you want to size your lights based on total canopy space.
For example, at Budseed we use 660w full spectrum LEDs per meter squared of Canopy grow space.
Lighting Schedules
Cannabis lightning schedules are crucially important when growing photoperiod cannabis. Precise and specific lightning schedules should be used during each stage of growth (seedling, vegetative, flowering) to achieve max yields and potency.
However, automatic cannabis, strains containing the ruderalis trait, can flourish under a variety of lighting schedules. The most widely used schedule is 18 hours of light followed by 6 hours of darkness. Growers typically find the 18/6 schedule to be the optimal balance between electricity consumption and yield. However, auto strains of Cannabis can be grown faster and larger under 24 hours of continuous light. There exist strains which can be grown seed to harvest in only 8 weeks following this lighting cycle.
Different light for Different Strains
Do different strains and cannabis types (indica, sativa) need different lighting schedules, intensity, light spectrum?
Short and sweet answer – NO!
Feel free to grow as many different strains of cannabis under the same lights. You can even grow auto strains with normal strains under the same 18/6 or 12/12 lighting schedules. More strains more fun!
Optimal lighting for Seedlings? Vegetative? Flowering?
Seedlings
When plants are seedlings, cloning, early stages (when only the cotyledon are present), they grow best in blue light. Many growers select less intense CFL bulb lighting fixtures to grow their seedlings and transition them under more powerful LED or HID lights once they enter the vegetative stage.
Budseed recommends giving your seedlings blue light for the first stage of growth at a low intensity (250-350w per sq. meter). Once the first set of leaves (after cotyledon’s) is present, the plant is ready for full spectrum light.
Too much light can cause seedling to sprout crinkled and burnt leaves.
Too little light and the seedlings can grow lanky and tall as they stretch seeking out more light. This is not optimal to maximize yield at harvest time.
Vegetative
In the vegetative stage, many farmers recommend 18 hours of light, followed by 6 hours of darkness. This is called an 18/6 light schedule.
Budseed recommends 24 hours of light, known as a 24/0 schedule.
The veg. stage is the money maker, it defines how large your plants will grow, how many flowering sites it will have come flowering stage, and how long it will take for your crop to be ready for harvest.
By keeping your plants under longer, more intense light schedules, the vegetative stage is prolonged allowing your plants to grow bigger and reach their genetic potential.
Photoperiod (normal) cannabis strains require 12 hours of uninterrupted darkness to exit the veg. stage and being flowering.
Auto strains will begin flowering automatically regardless of light schedule when they reach a certain age based on their genetics.
Flowering
For auto strains, Budseed recommends to stick with the 24/0 light schedule until harvest. For many indoor growers this minimizes stress from darkness period, and variations in environmental conditions that come along with lights out (temp and humidity spikes and drops). As mentioned before, the more energy you put into your plants the greater the yield you can expect. Under 24 hours of continuous light from seed to harvest, many auto cannabis strains can produce some insane yields.
For photoperiod/normal cannabis, stick to as strict 12/12 light schedule. Ensure there are absolutely no light leaks anywhere during the darkness period to achieve best results.
Reflectors, Side Lighting
Does side lighting actually work? Does it actually have a notable impact on yield? On the quality of the buds produced?
BigJ says stay away! Any lights you might plan to hang on the sides of a tent or a grow room to increase light penetration to the lower parts of the canopy would be better placed above the plants in normal fashion.
The plant orients itself, and its leaves and stems to expect light from above. You can observe this in real time by bending plants away from the light (known as low-stress training or LST) and watching as its leaves and stems move such that they again point towards the light source. Side lighting will cause stress to the plants, and will not be absorbed as efficiently as top-down lighting due to the orientation of the plants fan leaves (whose job is to absorb light via photosynthesis).
If you are having problems with LARF, BigJ recommends you take up a training technique to increase light penetration to the lower canopy, or even eliminate the lower buds all together prior to the flowering stage. Good choices are LST, Topping, and lollipopping.
Interested to hear what Budseed customers are using for lighting, love to hear from you in our comments section.
-BigJ