The Truth About PAR, Lumens, and Plants (May Surprise You)

PAR alone seems just as silly to me as the rest of the standards. Everything should be measured in at least three primary ways:

1) How many photons it emits from the entire bulb/emitter.

2) How many watts is lost as heat

3) A relative spectral output graph should be provided on each package, or made available on the websites in easy to find places.

Icing on the cake would be these as well:

4) PAR ratings
5) Lumens
6) Correlated color temperature

The last three are useless on their own, but when all 6 of these things are available, truly understanding which lights work and which don't for which application becomes enormously easier without needing to test every single one of them yourself. I think the heat losses are an extremely important measurement that should even be mandated by law. At whatever standard temperature and electrical conditions, device loses X number of watts as heat. Easy, and it tells us a lot about the true efficiency of the unit....

although no single measurement can represent all of the different manners in which plants can respond to radiation of different wavelengths, several measurements are common:

1. the number of electromagnetic energy units (photons) available on the leaf surface in units of microeinsteins(micro moles[um] and micro einsteins [me] are interchangeable) per square meter per second(ue/m2s). this is called a quantum meter.

2. the amount of radiant energy available on the leaf surface in units of watts per square meter(w/m2). this is called a radio meter.

3. pyranometer: measures par watts per square meter between 400-1100nm.

full sunlight=2000 um/m2/sec

=~450 par w/m2

=5,000 lumens

=50,000 lux

=1k mh/hps 1 ft away from plant(s)

plants par watt saturation point ~300 par watts/m2

plant requires ~ 20 photons to make+store 1 molecule of sugar

sunmaster warm deluxe states 345 par watts

luminous efficacy: the ratio of the total luminous flux emitted by a lamp to the energy cunsumed expressed in lumens per watt(lm/w).

mix of uvb+flouro+party lights[purple, green, red, teal/etc]+mh/hps provides broader overall spectrum. 1 each.

other cheap options for spectral enhancement:

cheap colored cellophane plastic (multiple colors) hung/reflected/wallpapered.

strobe light(s) of cellophaned flashlights.

christmas tree lights.

intensity vs. spectrum contentions end @ ~300 par watts, or, as close as any indoor gardener can replicate [note: as yet scientifically impossible], the full energy of the nearest star.

at certain point (~1ft from 1k bulb), saturation occurs. certain colors at certain linear (genetically) points in time of the annual plants will trigger certain chemical reactions. the several hues, and cloud covers, and gray days, and rainbows/etc influence growth/fruit production.

light science (indoors) has a great degree of importance, but just as influential (simultaneous to the light regimen(s)) are vapor pressure deficit, diff, ambient temps/root temps/average weekly temps/etc. all symbiotic and inseparable.

if light is @ ~300 par watts(optimum par watt saturation point), yet the vapor pressure deficit is high, and the root water source is low temped/unavailable, conditions will suffer.

increasing night higher than day temp may increase fruit production. w/ low vapor pressure deficit and higher root temps. many variables to consider when/once best-for-environment light source is found.

With all that being said, what is the best 600 watt bulb on the market for flowering?

am i right in thinking that a 400w cmh will produce more cannabis than a 600whps then?

i thought so, but a test proved ne wrong. besides the pure yield you have to watch out for the way the plant grows: mh/Hci: ball buds HPS: swort-like buds...

great information! would be nice to see a follow up in terms of a ranking or suggestion of lamps that would be ideal for our growing situations, etc. I mean I have a nice lux meter, but certainly am not going to go out and buy a par meter or anything of the sort just to hope to find a better lamp that may or may not tell me that it is more ideal for growing plants than another. years ago, I remember growing some excellent/healthy plants with a standard 400w hps.