# What light energy burns plants leaves.

• None

#### Hoodlegend

So been looking at lights. From what I gathered there's two important ratings LUX and PAR. When looking at setting them up most say hang it so its between 700 at 1000 PAR at the top of the plant. Some say between 80k to 100k LUX at top of plant. Now let's say I hang my light and I'm at 700 PAR at the top but my LUX is 150k. My question is what one burns the leaves to high LUX or PAR.

#### BigCube

This is a fundamental misunderstanding of light. Par and lux, lumens, candles or any other way of measuring light. Is all measuring the same thing. One isnt any different than the other.

Its like asking if miles or kilometers get you a speeding ticket.

#### gorillaglueaaron

##### š¦
Supporter
PPFD is the measurement of how much light a plant uses per meter squared per second. It is what you look at when deciding light intensity. The problem with measuring PPFD is that the meters cost hundreds of dollars. A quick and relatively effective alternative people use is measuring lux and translating it into PPFD. There is no straightforward equation for PPFD to lux or the opposite because it changes depending on the colour of the light (the spectrum).
This is the best calculator we have right now:

If you find the spectrum of your light, you can select it and input how many PPFD you'd like. and it will output how many lux you'll need.

Now to your question, the intensity at which your light will burn your plants depends on a lot of things but some pretty easy numbers to go by are:
Seedling: 300 PPFD
Vegetative: 500 PPFD
Flower: Up to 1000 PPFD

A cool thing to think about is that up to 2500 PPFD which is an insane amount of light, when people have too high light intensity, it actually has nothing to do with the light. A cannabis plant can handle up to 2500 PPFD (even a seedling) if it has all the other conditions perfect and adjusted accordingly. The higher the light intensity, the more nutrients it needs, the more CO2 it needs, the more water it needs... So when people "burn their plants" They actually just have an imbalance in one one of the other parameters. Now, that doesn't mean that you should suddenly bump up your lighting to 2500 PPFD because above 1000 it becomes very difficult to give the plant the perfect amount of everything it needs.

#### growsince79

So been looking at lights. From what I gathered there's two important ratings LUX and PAR. When looking at setting them up most say hang it so its between 700 at 1000 PAR at the top of the plant. Some say between 80k to 100k LUX at top of plant. Now let's say I hang my light and I'm at 700 PAR at the top but my LUX is 150k. My question is what one burns the leaves to high LUX or PAR.
GL with that 80-100k lux. Let me know how that works out for you.

#### Monkeybigbuds

How many lux is recommended for seedling 2 weeks old thank you