LED grow lights for marijuana used to be a waste of time except for very small clone, sea of green, and autoflowering gardens.
These days you can get LED grow lights that work as well as HID for full size photoperiod marijuana plants, while consuming less electricity, lasting longer, and generating less heat than HID.
But there’s something you have to know: to get your heaviest harvests and strongest potency using LED grow lights, you must properly adjust your hydroponics nutrients feed program, grow room environment, and light height.
Properly-designed LED grow lights made specifically for cannabis deliver light wavelengths that supercharge photosynthesis, plant metabolism, and resin production.
Your plants then require a specific set and ratio of nutrients elements they don’t get from regular feed programs.
The first thing to remember is most LED grow lights brands aren’t worth the money.
We’ve tested all major brands, including some that cost $2500+ per light.
The only LED grow lights we’ve tested that meet our standards are made by Lush Lighting.
As we used Lush Lighting LED grow lights, we noticed faster growth, earlier maturation, less bloom stretch, heavier resin production, heavier harvests, less grow op heat, and lower electricity costs.
But we also noticed that our plants need more water, magnesium, sulfur, and calcium, and that environmental conditions had to be adjusted.
First, nutrients issues:
- A magnesium deficiency shows up as deep green leaves with no other leaf problems, and stunted growth.
- Sulfur deficiency shows up as yellow or very light green leaves on new growth.
- Calcium deficiency shows up as dark green leaves with brown/rust-colored spots near the leaf margins.
Because deficiencies decrease photosynthesis, your plants may grow slowly, not gain height as fast, and seem sluggish.
Our method for feeding plants grown under Lush Lighting LED grow lights was developed after a year of experimentation.
Here’s the program:
- Feed 15-20% lower parts per million (ppm) of base nutrients than you normally would.
- Give your plants more water more often, but don’t overwater.
- Think of water as a nutrient, not just a delivery material for nutrients.
- Add Bud Candy starting three weeks into grow phase and keep using it until the final two weeks of bloom phase.
- If you notice calcium and/or magnesium deficiency, add Sensi Cal-Mag, but don’t use it past 3-4 weeks into bloom phase.
- Use pH Perfect hydroponics base nutrients. Most base nutrients have unreliable pH buffering which contributes to nutrients lockout of elements like magnesium and calcium. pH Perfect hydroponics base nutrients fix that problem.
- In bloom phase, use Bud Candy and Bud Factor X, both of which contain magnesium.
- Monitor leaf tips for burning (brown, crispy tips) and for too much light intensity (white tips).
- If you see brown leaf tip burning, reduce your parts per million. If you see white tips, move your LED grow lights higher.
- Lush Lighting grow lights are super intense, delivering unique ratios and types of wavelengths that drive plants hard. If you see your leaves folding down, it could be that your plants are getting too much light.
- For seedlings and clones less than three weeks old, keep LED grow lights at least 40 inches above your plants if not higher.
- Only when your grow phase plants are 20 inches tall or taller can they handle closer lights.
- Gradually decrease the distance between your canopy and your lights an inch at a time. By the time your plants are two weeks into bloom, your LED grow lights 20-24 inches from your canopy, depending on which Lush Lighting model you’re using.
- It’s desirable for your grow op to be about three degrees warmer than regular temperatures. For a non-C02 grow room, you can run about 79-80°F. For a C02 grow room, you can run about 83-86°F.
- You don’t want to add heat to your grow room when using LED grow lights, but if you see nutrients deficiencies when your grow room is cooler than 74-75°F, it could be that low temperature is affecting water intake and transpiration. This affects transport of magnesium and calcium in the plant.
- Increasing grow room temperature to 74-80°F, as long as relative humidity is 59-70%, is a good way to get plants to intake and transpire more water, which better transports nutrients inside the plant.
- Pay close attention to relative humidity and vapor pressure deficit when running LED grow lights. You want higher relative humidity during clone or seedling phase and early grow phase, lower during bloom phase especially with thick buds.
The main thing to remember is that growing with LED grow lights requires a different approach to lighting, hydroponics nutrients, grow room temperatures, and watering than growing with high intensity discharge (HID).
When you’ve calibrated your gardening methods and materials to take full advantage of LED grow lights, you’ll see why more and more growers are replacing their HIDs with LEDs.