JoseHempSeed

Here’s a little experiment I devised to add some life –hehehe- to the lighting debate.

I want to compare how a MH does in side-by-side tests compared with a HPS in the vegging stage. This is a scientific (yep, sure) and controlled (yeah, right) experiment and will no doubt be a benchmark for all future mj growers. Well, maybe not, but at least it will be fun…

Here’s the setup:

- the seedlings will all be treated in exactly the same way: watering, ferts, and light schedule (18/6). The only difference is the MH or HPS lamp. Each seedling has her own pot, and the potting soil is exactly the same (approx 75% soil and 25% perlite).

- the MH is a ‘regular’ 400 W Metalarc (Sylvania). The HPS is a Hortilux 400 W. I chose this lamp because it has the extra blue spectrum, just to see if it really comes close to the MH performance.

- the genetics of the experimental plants are very nearly identical, reducing the possibility of error. All the seeds are White Widow, from the same parents. I know this for sure, since they’re from my last grow.

- there are four plants under each lamp. all were germed at the same time, and all are just about the same size. At least right now.

- lamp height above the seedlings will be maintained equally. The reflectors are identical. Right now, the lamps are about 20 inches above the plants, and measured with a light meter, both sides are illuminated equally with about 4500 lu/ft. sq.

My plan is to record, on a weekly basis, 1) plant height, and, 2) number of leaves. From this data, we will be able to compare the foliage density and the growth rates. Then we should be able to settle the MH and HPS debate once and for all. hehehe. The experiment will continue until there is either a clear winner, or the plants get too big (or until I run out of bud from the last grow ).

Any comments or suggestions or ideas for improvements are welcome. I’d like to get some useful data from this experiment, and if you’ve got any ideas, I’d sure like to hear them.

And which bulb do YOU think will win? Correct guessers will win an all-expense paid vacation to...

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Delta

to do the test with?

Some guy did one on og a couple years ago, but from seed so much is debatable ...

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>|< Delta9420 >|<

JoseHempSeed

no,,,they're from seeds. but from the same parents.
and they really do look nearly identical - i was surprised how uniformly they sprouted and grew.
i'm hoping that there will be a clear difference in growth between the two lamps...

Knore

ide say the MH will win because its 100% focused on the blue spectrum which is used completely in vegetation -

the hps might have some other benefits though - maybe fatter stems or bushier growth - i guess we will see

And yes .. you should try it with clones

testing from seed has alot of variables but it will still work i suppose.

Also make sure none of the HPS light can leak into the MH area .. and vise versa

JoseHempSeed

yep, got the leakage solved...there's a plywood between the two sets, it's hard to see in the photo because you're looking at the edge...

seancharl

yes definatly use a clone because if you use seeds it wont be a controlled experiment because seeds even from the same parents have a different genetic profile which means different charecteristics .

JoseHempSeed

actually, the specific genetics are NOT that important

what we'll be looking at are growth rates, not the absolute comparison between seedlings. there's a big difference and it's a very important distinction.

it helps, of course, to have somewhat similar genetics, only in that the rates will (should) be comparable for this strain. that's why i used seeds from the same parents. using clones poses another whole set of problems, because it introduces too many variables we have no knowledge of, and therefore no control over, at least here in jose's shack

and don't forget our population is small - four plants per light, for a total of eight plants. it should be ok. we can look at the statistics later (using standard deviations, especially) and calculate how good the sample was. that is, if we want to get real scientific about it

Delta

We came from the same parents and look nothing alike ... genetics play a huge part in the rate of growth, for sure. Regardless of the fact the seeds come from the same parents, they have the potential to be vastly different within a wide array of characteristics. They will never be identical phenotypes and the question will always remain whether it was the genetics or the light that produced the results you eventually receive.

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>|< Delta9420 >|<

Knore

spot on delta -

you need to cut clones of equal length - then continue the experiment with them for more specified results

mother plants should all be from the same light too as this will affect growth rate

JoseHempSeed

good point. and the population is small, which will only tend to exacerbate that potential problem.

that's why we will look at the statistics later and see how good the sample was. then we should be able to tell if it was really the light or the genetics

i'm thinking there may be a strong enough difference between the lights...