sugaryDAVE
Well-Known Member
so how close can i get the plants to the uvb lightbulb? ??
10.0 Uvb Light
- Thread starter weedyoo
- Start date
'Bearded Dragon' should become the new nickname for green, or a strain at least. 
There's no real information on how close they can get yet. The only way we're working it out is by choosing lamps and distances that mean the plants are getting just about the same amount of UVB as they would near the equator - where the big crops of it grow.
The intensity varies vary dramatically with distance from the lamp - from too little to loads more than sunlight over a few feet.
There's no real information on how close they can get yet. The only way we're working it out is by choosing lamps and distances that mean the plants are getting just about the same amount of UVB as they would near the equator - where the big crops of it grow.
The intensity varies vary dramatically with distance from the lamp - from too little to loads more than sunlight over a few feet.
if using a fluorecent type uvb light, wouldn't that mean that you would get half of the emitted uvb light because the surface area of the lamp spreads in all directions?
I don't think so - but I had to think about it for a second.
The output ratings I've been using people have actually measured with a probe up against the glass. So 50% of the light intensity will already have been going off in other directions.
If you put a reflector behind it, I could guess you'd get about 2x as much UVB out the side that matters. I'm assuming most of the people who measured these bulbs didn't use reflectors during the tests.
Some of the more fair pet companies might rate their bulbs from further away, but I would guess a lot of them rate it with the sensor against the glass.
I love your grow log.
Damm, these Reptile EB Megaray bulbs are not fk'ing cheap! I've seen them priced around $120 -> 140 / £70.
Even more of a concern is that the UVB output is only normal sunlight at 2ft after about six months. When you first turn it on it's about five times more intense. So you'll be cooking the plants at first - moving the bulb vertically may be important. You'd need it about 5ft away at first, moving it about a foot closer every two months.
There's even a specific note with the bulbs that they're designed to spread light directly from the face, not diffused through a wider angle.
I think I'm going to hold off on buying one until I'm reasonably sure of good, consistent intensity and coverage.
Even more of a concern is that the UVB output is only normal sunlight at 2ft after about six months. When you first turn it on it's about five times more intense. So you'll be cooking the plants at first - moving the bulb vertically may be important. You'd need it about 5ft away at first, moving it about a foot closer every two months.
There's even a specific note with the bulbs that they're designed to spread light directly from the face, not diffused through a wider angle.
That's great for reptiles hiding out in a corner, not cool for grows where you want maximum coverage.
I think I'm going to hold off on buying one until I'm reasonably sure of good, consistent intensity and coverage.
HOHO
New Member
BloodShot420
Well-Known Member
i'm just past 5 weeks of flowering - i've had the uvb on for 10 hrs per 12 hr flower cycle...
no problems so far... unless you count heavy trichome production a problem
techgrower
Well-Known Member
Bloodshot, Is this a strain you normally grow to confirm more trichs then normal. Is anyone doing a side by side w/without to test benefits of uvb to mj? I read most of thread and very interested. Saw them today when getting fish food. 10uvb 26w was 19.99 spiral cfl.
HOHO
New Member
i found that my uvb was stunting the growth a little but i think it was because i had the light to close...the pistols were only coming out the sides of the buds..so i turned off the uvb for the last week and raised it a smidge and turned it back on yesterday..
i have also been battling other things in my garden unfortunately,like hermies from a light leak and i had to much faith in my tds meter and it burnt us pretty good at the start of this grow and had to guess the nute levels for the first 3 weeks of flower while a good one came in the mail..
ya know i am kind of going out on a limb here but i think that when the plants sense that there are dangerous levels of uvb they almost instantly send a signal to pump thc in to the trics to protect seed pods and that you may not need to have these bulbs on every plant every day cuz most of the trics that i see turn milky way before they would with just hps.. i could just be high..
another thing to try is pull a bud at about 5 weeks flower to see if its better with uvb
i have also been battling other things in my garden unfortunately,like hermies from a light leak and i had to much faith in my tds meter and it burnt us pretty good at the start of this grow and had to guess the nute levels for the first 3 weeks of flower while a good one came in the mail..
ya know i am kind of going out on a limb here but i think that when the plants sense that there are dangerous levels of uvb they almost instantly send a signal to pump thc in to the trics to protect seed pods and that you may not need to have these bulbs on every plant every day cuz most of the trics that i see turn milky way before they would with just hps.. i could just be high..
another thing to try is pull a bud at about 5 weeks flower to see if its better with uvb
compqt
Well-Known Member
Here's a piece from an article:
OVERTON -- Short treatments with a particular type of ultraviolet light results in more marketable bedding plants and vegetables, according to preliminary work done by a Texas Agricultural Experiment Station horticulturist at Overton.
Dr. Brent Pemberton has found that exposing plants such as impatiens, tomatoes and cucumbers to ultraviolet B, (UV-B) treatments for a few hours slows their foliar growth and stem length without reducing color or other favorable characteristics.
"Simply put, it acts as a growth regulator and stunts them somewhat, but with bedding plants this may be desirable," said Pemberton, who is based at the Texas A&M University Research and Extension Center at Overton.
Bedding plants are often grown from seedlings in greenhouses. The growing conditions in a greenhouse cause many plants to outstrip their containers, growing too tall to be easily transported by the time their color matures. Plants overly tall for their containers may also be aesthetically displeasing, which can hinder their marketing.
Height control of greenhouse-grown plants has long been an issue in the bedding plant industry. Chemical growth regulators are often used on ornamentals but are not considered safe on vegetable crops. Using UV-B to regulate growth is a relatively safe alternative that seems to work on some bedding plant species as well as select vegetables, Pemberton said. While some plant varieties show a promising response to UV-B, others don't. For example, Pemberton has found the technique does not work on annual periwinkles. While pansies, an important East Texas greenhouse crop, show some positive response to UV-B, much work remains to be done
OVERTON -- Short treatments with a particular type of ultraviolet light results in more marketable bedding plants and vegetables, according to preliminary work done by a Texas Agricultural Experiment Station horticulturist at Overton.
Dr. Brent Pemberton has found that exposing plants such as impatiens, tomatoes and cucumbers to ultraviolet B, (UV-B) treatments for a few hours slows their foliar growth and stem length without reducing color or other favorable characteristics.
"Simply put, it acts as a growth regulator and stunts them somewhat, but with bedding plants this may be desirable," said Pemberton, who is based at the Texas A&M University Research and Extension Center at Overton.
Bedding plants are often grown from seedlings in greenhouses. The growing conditions in a greenhouse cause many plants to outstrip their containers, growing too tall to be easily transported by the time their color matures. Plants overly tall for their containers may also be aesthetically displeasing, which can hinder their marketing.
Height control of greenhouse-grown plants has long been an issue in the bedding plant industry. Chemical growth regulators are often used on ornamentals but are not considered safe on vegetable crops. Using UV-B to regulate growth is a relatively safe alternative that seems to work on some bedding plant species as well as select vegetables, Pemberton said. While some plant varieties show a promising response to UV-B, others don't. For example, Pemberton has found the technique does not work on annual periwinkles. While pansies, an important East Texas greenhouse crop, show some positive response to UV-B, much work remains to be done
weedyoo
Well-Known Member
i dont know what plants they did tests on besides the ones they takled about.
but were these plants that grow better at the equater where their is high uvb. good read thanks rep
youandiunderwater
Active Member
I split my first grow with a UVB reptile light and noticed the difference in the green of the plant. Couldn't tell much growth change, but UVB keeps a nice color to them.
techgrower
Well-Known Member
Right now I am flowering 1 plant with 2x 2" T-5 ho floros, 8klumen ea., full spectrum, would only one tube be nesc for me? I can swap out a 6500k bulb for one uvb bulb easy, or should I use 2? Light is about 4-5" from top cola, allready lst'ed down have great side growth. I am not as good as some here with the mathmatics. so 1 or 2?
BloodShot420
Well-Known Member
yeah - this is my third flowering cycle with DP blueberry - i cant really do a side by side comparison since i have only 1 flower room... since the last crop, i changed all nutrients to the full advanced nutrient line... and added some more uvb lights
i noticed that by 4 weeks of flower the buds and leaves at the canopy level were already covered with trichs... i know someone else thats got a crop at 4 weeks of flower too and mine are doing much better - but the other one is CFL only, and mine is @ 2KW
i accidentally broke off a side branch earlier this week - and dried it for a couple days and for 5 weeks of flower that shit was intense... it was MUCH better than some regular street weed that i had at the same time (decent stuff, nice hard nugs, not bricked, and only a few beans)
HOHO
New Member
it was about 7 inches but keep in mnd that i have a 160 watt flood lamp..i raised it about 2" and just leave it on all day..