Changing between HPS and MH during flower???

i understand that many people start with a MH to reduce stretch and then swap to HPS.

also i read a DJ short article that implied he changed back to MH to finish flowering as he thought it made for better aroma etc

has anyone got any experience of doing this???

what i wonder is if the plant's ability to photosynthesize is compromised by suddenly changing the light spectrum - does the plant produce it's chlorophyll in reaction to the available light spectrum or can it instantly adapt to a changed spectrum?

thing is i run a perpetual scrog so all my plants are at different stages and i wondered if swapping over and back now and then would be detrimental to plants further on in flowering.

thanks

V.

hay V..

years ago i saw the increese in quality and especialy weight with adding a MH bulb late in flower,,,,,its almost odd to hear you guys only getting on to this now.....

i cant remember if ive personly ever switched compleetly, between HPS to MH late-in-flower..., "switching comleetly" is not so common as switching 1 HPS for 1 MH in a 3 light grow,,,,,i advise peeps to do this for higher yealds

the increese in yeald from adding the MH is massive,,,more than noticable,,,its funny !,,,,but if you want my advice,,,adding MH at any point increeses yeald massivly!!,,,,,,if used alone HPS systems are crap!!,,,,

imo, hangin a HPS in a new jazzy growtent its like havin a tubeTV in your newly decorated livingroom when the sony 46inch 1080p sits in Dixons..

HPS is just not good enough as a stand alown system...!!!!!!!!!!!!!!

everytime i talk about lights and ballasts, yeald/weight,,,,......,"forgetting Lumens for a min,",,, i will allways talk about the rooms score on "CRI" an the bulbs Kelvin ratings ,,,[the picture below will show you the correct Kelvin ratings for plant life cycles],,,,plants want differnt Kelvin ratings at different times of there life,,,,its that simple,,,,,,,,,,,,,,,,,not giving the plant the required Kelvin ratings or CRI could be viewed as stress........

people allways ask me..."what ballast should i buy, what bulbs should i buy?",,,,,my answer is always HOW MUTCH TO YOU WANT SPEND!!??

an if they ask me "well whats the best?".....i put this infront of them,,

HydroFarm said:

"Sun Pulse Pulse Start Metal Halide Grow lamps were created by the GAS Technologies group of photo-biologists, plant scientists, mechanical and electrical engineers, gas chemists, and HID lamp designers. They are designed with true solar symmetry for true photochemical reactions in living organisms, greater molecular efficiency in operations, and better color rendering. Sun Pulse lamps are made with the highest quality and quality control."

* Available in Kelvin ratings of 3k, 4k, 6.4k, & 10k

Click to expand...

im supprized this only beeing talked about now on icmag,,,,,,ive been mixin and matchin suplimental light for years , an im allways interested in "increeseing optimum growing conditions"

this is something somone did after they listened to me jibber for an hour or 2,,,,,the dude sent me picks,,,hes a nice guy

hi rick! - they look awesome, but with only one light in my setup and plants at different stages im not sure i could swing it.

im wondering if CMH is going to be my best option. i get great results with hps atm but i think slightly less internodal distance might be better and i wonder if a more balanced spectrum will give better quality weed.

i did buy a MH bulb to use at the start of flower but as my modular scrog is perpetual now i wondered if i could still wack the MH in for a week now and again when i need to - and it not affect the other plants further into flower.

i sound like im in my mates shop

check this out bro,,,,the best kit to get for a single light system is a digi ballast with a highpressure MH sunpulse bulb,,,,

remember you get no frequency with the digi ballast witch is a massive benifit compared to magnetic ballast........[[ "magnetic ballasts are actual OFF 40% of the time,,,this is because of the frequency",,,"frequency is the reason WHY you see lines in you photographs when you take picks of your grow"]]]....,,,


a sunpulse bulb with a K of 3 is wickid for mid flower,,,,but if you check the chart above,,,you will see that plants love a rise in K towards the end

the reason why peeps buy the sunpulse especialy, is because it gives a better CRI rating in mid flower than HPS,,,,,mid flower is when HPS would normaly used an thats where it all goes to pot,,,,,imo HPS only gets used because its cheap for 3K bulbs,,,,extra light should be used with HPS,,,,imo

K levels are easy to follow if you want to,,,or can do

but i gota admit,,, everything ive said is not essential to smokin weed,,i could easly just grow weed with 50p in my pocket ,10 seed, a coke an a smile

I wonder, how do the megagrowers with a zillion lights handle this? Do they go around swapping out lights and ballasts?

I bought my lights as kits, with a HPS ballast, and a MH conversion bulb thrown in. I noticed that the MH conversion bulb has significantly fewer lumens vs. the HPS, I guess because of efficiency lost in the conversion.

I just started a new grow after a break of over a year, and I'm going to go HPS start-to-finish and see what kind of results I get. Previously I've started with the MH and finished with HPS.

digital ballasts do both mh and hps

KermitTheHermit said:

I wonder, how do the megagrowers with a zillion lights handle this? Do they go around swapping out lights and ballasts?

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this is the problem

its ok if you only have 5 lights, but to fork out for digis/decent mh AND hps bulbs is ridiculous if you are running alot of lights/alot of setups...

KermitTheHermit said:

I wonder, how do the megagrowers with a zillion lights handle this? Do they go around swapping out lights and ballasts?

I bought my lights as kits, with a HPS ballast, and a MH conversion bulb thrown in. I noticed that the MH conversion bulb has significantly fewer lumens vs. the HPS, I guess because of efficiency lost in the conversion.

I just started a new grow after a break of over a year, and I'm going to go HPS start-to-finish and see what kind of results I get. Previously I've started with the MH and finished with HPS.

Click to expand...

only peeps in scientific circles are interestested in goooooood lighting,,,,most peeps are happy with a smoke and a half-decent yeald at the end of the day

if you want to get scientific,,just follow the K chart in the above picture and you cant go wrong,,,, you wouldnt hassle yourself if your growing 1000`s of plants ,youd just stick to the 3K

using a digi ballast and switching K`s makes a massive difference in yeald,,,il tell you that for free

sorry,,,,4K is the comprimize for the big grow`s

I run 4k right now in a soil grow.. My ratio of mh to haps is 3 hps and 1 mh. I have homemade tables that i rotate so each plant will spend about 2 weeks under hps and 6 in flower. I cannot say for sure if it makes a difference because i have always done it in this setup because I had the bulb to do it and I imagine a mixed spectrum is better than more specific spectrum.

fireman

englishrick said:

HPS is just not good enough as a stand alown system...!!!!!!!!!!!!!!

Click to expand...

http://www.icmag.com/ic/showthread.php?t=139811

hmm, sure hps grows some lovely smoke - ive used just hps for flowering myself for the last few runs.

BUT a look at the light spectrum of hps will show us that it is rather lacking in a balanced spectrum so i certainly think it can be improved upon.

does hps grow good weed? - yes
does it grow the best weed? - perhaps not.

i for one think that well grown outdoor weed can be a bit more potent and psychoactive and this is likely to be down to the spectrum it receives - so if there are bulbs that will recreate that indoors then i would consider them- but trying to integrate them into a perpetual system or a one bulb system might be problematic.

im still thinking cmh may give the best of both worlds - especially for smaller bulbs where you havent got the choice of sunmaster etc.

V.

but my question remains from the OP

if i could only have hps or mh, i d take the hps...

for large scale grows, we run a combo of 1mh - 3.5hps

it makes alot more sense than buying digis and switching bulbs (price wise)

VerdantGreen said:

hmm, sure hps grows some lovely smoke - ive used just hps for flowering myself for the last few runs.

BUT a look at the light spectrum of hps will show us that it is rather lacking in a balanced spectrum so i certainly think it can be improved upon.

does hps grow good weed? - yes
does it grow the best weed? - perhaps not.

i for one think that well grown outdoor weed can be a bit more potent and psychoactive and this is likely to be down to the spectrum it receives - so if there are bulbs that will recreate that indoors then i would consider them- but trying to integrate them into a perpetual system or a one bulb system might be problematic.

im still thinking cmh may give the best of both worlds - especially for smaller bulbs where you havent got the choice of sunmaster etc.

V.

but my question remains from the OP

Click to expand...

that Bullshit Button is cool..

outdoor hits 100 on the CRI ,,,,HPS typicaly only hits 22 CRI,,,,

imo ,,,having a higher CRI = Better Weed,,,,especialy in the weight/yeald department!

i agree with you V,,,,,HPS systems grow GOOD WEED without supliments,,,but its not a bulb for an EXTREEM PRO.....

MH vs HPS.....MH wins hands down!

somebody hit the button if they im wrong,,,,

A friend of mine that owns a hydro shop near SFO swears by switching to MH the last 7 days of flowering. He never mentioned a yield increased, but said that more aromas come out. It's great to read the science behind it now

I have 2 hydrohuts for flower in one tent I have a growzilla hood with 600wt hps and 400wt mh bulbs in the other i have a single 1000wt sunmaster hps. both tents are growing serious seeds hdf, grown in 1 gal hempy buckets using cocoa, nutes is rez's gh feeding schedule. the dual spectrum out performs the single hps every time. buds form about a week earlier they also get fatter and finish earlier as well. there is such a huge difference i just replaced the hps with a dual arc bulb.

Light Or Fight? How Plants Make Tough Survival Choices

ScienceDaily (Mar. 2, 2009) — Ever since insects developed a taste for vegetation, plants have faced the same dilemma: use limited resources to out-compete their neighbors for light to grow, or, invest directly in defense against hungry insects.

Now, an international team of scientists at the Salk Institute for Biological Studies and the Institute of Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agronomía (IFEVA) has discovered how plants weigh the tradeoffs and redirect their energies accordingly.

The same light sensor that detects other plants crowding in and gives the signal to switch on the synthesis of the plant growth hormone auxin reduces the plant's responsiveness to the hormone jasmonic acid, which orchestrates the synthesis of a whole array of defensive chemicals, the researchers report in an article published in the current early online edition of the Proceedings of the National Academy of Sciences.

"Understanding how plants resolve the dilemma of resource allocation on a mechanistic level opens the possibility to increase the natural defenses of crops, especially in the high density plantings typical of modern agriculture, which depend on regular applications of insecticides," explains senior author Carlos L. Ballaré, Ph.D., a senior scientist with CONICET (the National Research Council of Argentina) and associate professor at the University of Buenos Aires.

In an earlier study, Ballaré discovered that plants dial down their investment in defense when they perceive an increased risk of competition for light. But just how changes in light quality caused plants to drop their guards were still poorly understood. To connect the two, he turned to Howard Hughes Medical Institute investigator Joanne Chory, Ph.D., in the Plant Biology Laboratory at the Salk Institute and former lab member, Yi Tao, Ph.D., who had dissected the molecular pathway that plants use to adjust their growth and flowering time to shade.

Plants sense the presence of other plants in their neighborhood by the relative increase in incoming far-red light resulting from absorption of red light by canopy leaves and reflection of far-red light from neighboring plants. "When the major photoreceptor for shade avoidance detects neighbors, plants start producing the growth hormone auxin and transport it to their stems, where it helps plants grow taller," explains Chory.

But plants also react to chemical cues in the oral secretions of herbivores and mechanical damage caused by caterpillars and their ilk nibbling on foliage. They increase the production of defense-related hormones, particularly jasmonic acid, which ramps up the concentration of chemicals that make plants unpalatable or at least less nutritious for herbivores.

"Such responses incur what is known as opportunity costs," says Chory. "Resource allocation to competition can limit investment in defense, increasing vulnerability to herbivores, while allocation to defense can reduce competitive ability against neighboring plants."

And that's exactly what first author Javier E. Moreno, a graduate student in Ballaré´s lab, found. Fall armyworms—caterpillars that prefer to chomp on corn, sorghum and other members of the grass family but won't say no to beans, potatoes, peanuts, cotton and other crops—grew twice as fast on Arabidopsis thaliana seedling grown under crowded conditions or exposed to far-red radiation, the light signal plants use to detect the proximity of neighbors. Like many commercially grown crops, Arabidopsis — the lab rat of plant biologists — doesn't tolerate shade well.

But it was more than a matter of limited resources. Mutated Arabidopsis seedlings that no longer responded to far-red radiation but had normal levels of the far-red photoreceptor, still let their defenses down. At closer inspection, the researchers found that far-red radiation decreased the plants' sensitivity to jasmonates. By ignoring jasmonate signals, the plants save resources because they no long invest in defense and, at the same time, avoid the growth-inhibitory effects of jasmonates.

"Without sufficient light to keep photosynthesis going, plants won't have enough energy to invest in sophisticated defense strategies," says Ballaré. "Coupling shade avoidance syndrome with the regulation of resource allocation to defense could provide a major selective advantage for plants growing in the wild, but might increase the vulnerability of densely planted crops to insects."

http://www.sciencedaily.com/releases...0227161823.htm


From what i gathered far red light has an effect of slowing down jasomic production which would be used to trigger a plants defenses. In the case of Cannabis it would diminish Trichome production. BOG has stated he uses diminished light level towards the end of his grows for potency. This can be seen as lowering the levels in the far red light allows the plants mechanisms for defense to function again.


This coupled with the stress from not watering would ramp up the Jasmonic levels and in turn increase Trichome production. All this information can be used in the growers favor, timing would be really key because Jasmonic also slows and or stops growth and would not be as effective i guess if started at the wrong time. also a shift in light spectrum towards the end flowering in favor of less far red would probably help, but only experimentation will tell.


Hope this helped furthered the discussion on this topic

i am not sure about shifting light spectrums at the end, but i know people that give 48 hours of dark before cutting