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cabinriver started grow question 4 years ago
I started the light off close to the plants and have been raising it up as they grow to prevent light burn - is that the general idea or am I doing it backwards?
Auto OG Kush
17 weeks
Auto OG Kush cabinriver
Auto OG Kush
37 comments · 4 years ago
Week 4
Techniques. Defoliation
SensiSmellYahLater answered grow question 4 years ago
This is indeed the general idea and you are correct in your assumption my friend. Cannabis plants want three things from their light. High concentrations of PPFD in the range of 1500 - 2000 PPFD, Relatively stable heat from the light source around 70 - 80 degrees Fahrenheit and light in the correct spectrum for the stage of growing that they are in which means more blue and white light during vegetation with a small amount of red spectrum mixed in and then more red spectrum with some blue and white spectrum mixed in for flowering. Depending on the light source that you choose to use you would want to keep your light as close as 12 inches from the plants if you are working with low powered and low temperature LED's to up to three feet from the plants if the light source is incredibly powerful such as HPS and HID's. Measuring the amount of light using a PPFD meter and measuring the temperature of the top of your growth canopy can give you a good indication of when you should be moving your light upwards or even possibly lowering your light closer to your plants. I hope I've helped my friend. Cheers.
HighTV answered grow question 4 years ago
Nice question @cabinriver! That's actually exactly how it typically works. Put the light far enough from your hand so it doesn't burn after 30 secs and use that spot. If you are not seeing any burns I suggest not raising the light at all unless you need a wider reach with it. Typically I only ever raise my light to better reach the edges of my tent or when temperatures are to high. As long as these things are good you can have it touching really :sunglasses:
goarilla answered grow question 4 years ago
Put a hygro/temperature meter at the canopy level in a representative spot. Now you don't have to
guess as much whether it's lightburn or excessive heat.
MUDBUG answered grow question 4 years ago
At this stage and from the height i see in that pic u good and it looks like u running a qb you are good on height if u get any signs it will be because of a deficiency not light burn and you always start higher u need to check your height specks for your light a good rule of thumb is always start high on the light and go down as needed your plant will drup like shes underwatered if you start getting light stress it will be very hard to get light burn from wat i see:writing_hand::writing_hand::writing_hand::writing_hand:
Stick answered grow question 4 years ago
Hi @cabinriver! Your process looks fine to me, this is particularly true with LEDs, because each model has a different optimal distance. Nice plants, keep up the great work, and happy growing :facepunch:
ShaggyGrower answered grow question 4 years ago
Leaf tip burn is likely nutrient burn. Light burn is in the middle of a leaf - looks like an oblong yellow blister. LED's need to be a bit further away than HPS (CFL can be cm's away), so have the led ~18inches away at the closest imv. Happy Growing!
OneDude answered grow question 4 years ago

light can be too much and burn the leaves. With Co2 addition and enchached habitat, you can move the bar up.
closer to the light, exponential is the moles (unit of measure of light, there are different value for different wavelenghts, etc) of light that you will give per square meter
closer to the light, the less the plant will stretch. Different enviroments and strain will result in different results as well
the better the feeding, the more energy you can give to the plant

usually people tend to do the opposite, also because small plants can take less energy than an adult plant :)
the initial stretch, will allow you to "shape" the plant, with training, into the best fitting surface for the light to cover the buds, such as is kind of a plane.
When she start flowering, you want to give her more light to stimulate vigorous flowering.
CRiSPrGrow answered grow question 4 years ago
your lights are around where you want them to be no higher than this, then when the flowering starts a few more inches away no more than that. just be careful maintaining the lamp to plant distance during veg + flower stretches , you want to be checking up on them regularly. Hope this helps ! :rocket:
The_Projexx answered grow question 4 years ago
That's the general idea behind it , you could also do it the other way around if the plants were raised off the ground lower them to the ground it would have the same effect . You will notice light burn far before its to late tho the leaves will curl upwards and form a sort of taco shape . From what I can see in your grow is that these plants are in no way shape of form suffering from any light burn at all :) they look happy and quite healthy ! The optimum height for lamp is to be at 50 cm away from your plants , if you can get it closer without risking burn great , but 50 cm away is a perfect height (or closer depending if your at risk of light burn or not) for the light if you can get that dialed in your going to be golden ! I hope this information serves you well on your journey to becoming a Master Grower ! -Happy Growing!
Removed answered grow question 4 years ago
That's perfect. Keep doing it. That way the plants will always be as close to the light as possible. This will also help in preventing unnecessary stretch. Good luck