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How much will I yield?


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#1 HeadPawthead

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Posted 04 August 2007 - 10:36 AM

This is a re-post, but it is helpful......

How much will I yield?
"I have XXX watts...how much will I yield?" or "How can I get
bigger yields?"

A common inquiry. From ambitious new gardeners and for good
reason too. But, this is really a loaded question that doesn't
have a definite answer. It seems one of the first assumptions by
new gardeners is that loads of light automatically equals loads
of buds. Unfortunately, it's just not that simple. Yield is
equally contingent on a number of factors; light, temperature,
humidity, water, nutrients, CO2/ventilation, genetics, etc. Think
of it as an engine, with each factor of cultivation representing
a single piston, sure the engine will run if some of the
cylinders are misfiring or not firing at all, but to yield the
most power from that engine, all cylinders must be firing in sync
and at maximum capacity.

Temperature. Most cannabis plants will slow or cease growth when
temp's get above 85F, or below 65f. Optimal lights-on temp for
most strains is about 72-78F, with 5-10 degrees cooler during the
dark period being a good rule of thumb. (Unless co2 is used)

Humidity. Cannabis does best around 45%-55% RH (relative
humidity).
During veg and late flower, however letting it drop lower during
the final two weeks of flower is advised, as it will help prevent
mould problems.

Water/moisture. Cannabis generally doesn't like "wet feet", or a
soggy environment, so it's very important to have a fast draining
soil/soil-less mix (or well aerated solution in a hydro garden).
Wet or damp conditions can also lead to mould problems during
flowering.

Nutrients. Cannabis will require a variety of nutrients at
varying NPK ratios during its existence. NPK stand for; nitrogen
(N), phosphorus (P), and potassium (K)-the three major nutrients
used by plants. Simply put, your plants will need a fertilizer
with more N than P and K during vegetative growth and fertilizer
with more P than N and K during flowering. Using any well-known
quality fertilizer applied per instruction @ ½ strength is a good
place to start. Organic, chemical, or somewhere in-between is
another choice to be made and is a totally personal one. There is
a plethora of fertilizers on the market, but the best fertilizer
is the one that's used properly.

CO2/ventilation. Plants require CO2. There is sufficient CO2 in
our atmosphere to support massive bud growth, but when growing
inside you must either have adequate ventilation (the volume of
the room exhausted at least once/5 minutes) to ensure that there
is a constant supply of fresh, CO2 enriched air or one must have
supplemental CO2, which requires higher temp's and more nutrients
to be utilized effectively.

Light. Typically, the more the merrier, but more light will
create stronger water, nutrient, and CO2 demands on the plants.
You must also have the proper spectrum of lighting as well as a
means of efficiently reflecting as much of the light as possible
into the garden's canopy. The norm is to use more bluish light
(Metal Halide, cool-white fluorescents) for vegetative growth and
more reddish (High Pressure sodium, warm fluoro's) light for
flowering. Though it's possible to grow great buds under
fluorescent lighting and a few will even argue their superiority
to HID's, most indoor growers use High Intensity Discharge lights
such as MH and HPS, and many use fluoro's for vegetative growth
and HPS for flowering. It's very important to have the light as
physically close to the canopy as possible without burning the
foliage and still allowing for even coverage.Many new growers
believe that "Droppin the light" closer to the plant will be
beneficial. Besides heat stress, the bulb puts out radiant energy
that causes leaf burn (Note it is possible to complete a grow
using just HPS or MH)

Genetics. Its an easily overlooked factor. Some strains simply
have the potential to yield more than others. Having a
heavy-yielding strain doesn't automatically equal big yields,
either. It only means that the potential for heavy yields is
there. The grower must provide the optimum environment for that
particular strain in order for it to be able to reach it's yield
potential, and each strain has slightly unique requirements.
Also, within a strain there are usually several phenotypes, each
of which will exhibit unique characteristics which is to say that
some pheno's of a particular strain will weigh more than others.
Plant/root/container size. Obviously, the longer a plant is
veg'd, the bigger it will get and the more it will yield. Almost
always overlooked because they're unseen are the roots. Root mass
is directly related to bud production. Simply put, the more roots
you have the more bud you will (potentially) have. Be sure to
always allow plenty of space for the roots to grow and spread
out, even more-so in soil A general rule of thumb is 1 gallon of
soil for every foot of plant height. This is also the reason I posted
the thread about air-layering, titled bigger yeilds for your plants.

System.
Scrog/Sog/Vertical gardens
These systems have a higher g/w/time yield than comparable large
plant system over the same time period.
Grower's skill. Growers can add yield by: using additives (like
B1, kelp, enzymes), foliar feeding, and topping/FIM/
In addition. Tricks like keeping nutrients and the air temps warm
during night cycle can help final yield. Although it's a topic of
hot debate, it's generally thought that any system that supplies
the roots with maximum oxygen (aeroponics) would outperform a
system that restricts 02 input such as (soil).

So, as you can see there's much more to yield than throwing some
plants under tons of light with tons of nutes. Before one becomes
too concerned with yield, one must first learn how to grow plants
well, learn how to "listen" to the plants and give them just what
they need. It's best to start with simpler methods, in fact, I
think the simpler method is always the better one. Learn how to
grow strong, healthy, fast-growing plants and the yields will
come.
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#2 Roseman

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Posted 04 August 2007 - 11:32 AM

I want to add some info on Lights to Yield and How Much Light do I need.
I've seen so many silly rules of thumb, like a half gram of dried bud per watt of light.
How much light is needed for growing?
The answer depends on if you are growing small plants, in a small space, or large plants, and have a larger space to grow in. I'll try to answer this "in general" .
Light seen and perceived with the human eye is measured in Lumens. There is an ideal amount of lumens for growing and a minimum amount of lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use.
(Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer clear day).

Determining lumens for your grow area:
First determine the square footage of your area (example in a 4 foot by 4 foot area, there is 16 square feet) If you have a 1000 Watt High Pressure Sodium Light Bulb, that produces approximately 107,000 lumens. Divide this by 16 (your square footage) 107,000 divided by 16 = 6687 lumens per square foot. So just divide the total amount of Lumens, by the total amount of square feet, and that's your lumens per square foot.

How far away from my plants do the lights go?
The lights in your grow room should be as close as possible to the plants without burning them. There is no such thing as too much light, unless there is overly sufficient heat to dry out and burn the leaves. A good rule is to put your hand under the light, if its too hot for your hand, chances are that the plants will be too hot too, so move the light up until your hand feels more comfortable. For seedlings or sprouts or babies, I keep them a little further away from the light, because they are very susceptible to burning and drying out, at these young stages.

How do I decide which lights to use?
Efficiency is very important when choosing a type of light. The wattage is not the most important thing, different types of light produce different amounts of lumens per watt. For example, a 300 watt incandescent will produce about 5100 lumens. (not that you can grow with incandescent bulbs) While a 300 watt Metal Halide (just an example, they do not come in 300 watts), will produce 27,000 lumens. Obviously far more efficient for growing, while still using the same amount of electricity.

Approximate light production:
Incandescents: 17 lumens/watt
Mercury vapor: 45-50 lumens/watt
Fluorescents: 60-70 lumens/watt
Metal halide: 90 lumens/watt
High pressure sodium: 107 lumens/watt


Incandescent lights: Incandescent bulbs are the most popular type of lights in the world. They may come advertised as incandescent, tungsten, quartz, halogen, or simply standard. The important thing about incandescent bulbs when it come to growing is simply this: they suck. Using incandescent bulbs to grow plants is like trying to flag down the Space Challenger with a burnt out match! You can do it, but it won't work. They are like Big Titties on a nun, good for nothing. There are some incandescents which are sold as "grow lights." They usually have a blue coating and usually come in 60W and 120W sizes. While they may seem like a good choice to new growers, they are next to useless; they produce some light at a usable spectrum, but only have about a 5% efficiency and generate more heat than usable light. Most of us have these in our homes right now. Don't use them for growing, instead opt for a Spiral Compact Fluorescent (CFL) as a cheaper but more efficient alternative.

Fluorescent lights: Fluorescents are far more useful than incandescents. They are efficient enough, and much less expensive than HID (High Intensity Discharge) lights. Compact fluorescent tubes, (commonly called CFLs) are popular with growers because of their good output to size ratio. Compared to standard 4 foot tubes, CFLs are smaller, more easily moved, and more can fit into a given area. CFLs are good for small grows on a tight budget, and for novice growers, since they do not require any special sort of wiring or understanding of the necessary bulbs for a given fixture, and the small wattage ones (23, 42 and 65) are very widely available from Lowes and Home Depot. Fluorescent lights come in many different Kelvin (spectrum or color) ratings; often the spectrums are labeled on packaging as being 'cool white' or 'warm white.' Cool white is more blue, and is good for the vegetative stages of growth. The bulbs are ultra white. Warm white light is more reddish in spectrum, and is best for the flowering stage. The bulbs are almost cream colored.

Color rating - Measured in Kelvin (K). The higher the number, the more bluish the light. 4000K-7000K is mostly on the blue side of the spectrum for Vegging or GROWING, while 3000K and under goes from a white spectrum, to a redder spectrum and is best for BLOOMING or FLOWERING.


High Intensity Discharge (HID) Lighting Systems:

Mercury Vapor (MV)
Mercury vapor lights are not the most efficient light for growing. They are very bright, and relatively cheap. They do emit light at the wavelengths necessary to support your plants growth, but not nearly as good as a MH or HPS light. Much of the light emitted by MV lights is bluish-white. Street lighting is what most MV lighting is used for.

Metal Halide (MH)
Metal halide lighting systems are optimal for use in the vegetative phase of growing. They emit mostly blue light, which encourages vigorous growth of foliage. They are very efficient, but can get rather expensive to start with; fluorescents may seem more appealing because of their lower price, and they are not much different when compared on a lumen-to-lumen cost level. These lights can be used through-out the grow, but leave a lot to be desired in the BLOOM stage.

High Pressure Sodium (HPS)
High pressure sodium lights emit mostly orange, yellow, and red spectrum light, which is perfect for the flowering stage of the plants growth. They are (in my opinion) the most efficient type of light available for any application if you are not on a budget and can vent the grow area for heat. HPS lights can be used through-out the entire grow. They produce more dense and usually larger flowers or fruit than any other light. HPS lights are generally a little more expensive than MH systems of similar wattage. They are more commonly used by experienced commercial growers because of their ability to produce tighter denser flowers or buds, higher lumen-output-per-watt, and will produce from start to finish.

Just like everything else, available grow lights are evolving. Remember how the sun produces 10,000 lumens per square foot in the mid-summer. Well, today you can actually buy CFLs that can actually duplicate those lumens. If you can not grow under the sun, then bring the sun inside. Yes, you can have 20,000 lumens covering the entire 4 square foot grow space with the new 105 watt per bulb CFLs in a custom reflector. Three of these bulbs in the proper reflector actually yields 20,000 lumens!


I should add "in my humble opinion" because the debate on CFL and HID lights is never ending!
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#3 4kaan4

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Posted 22 December 2007 - 11:42 AM

You covered the light issue quite well. I would tell any newbie or private use grower to go with fluoros just because they are cheap and easy. They are also a good deal less massive and easier to hang. I use them almost exclusively because, as you pointed out, they are cooler to operate.
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#4 Hobo

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Posted 22 December 2007 - 12:23 PM

Great post, a good recap on the fundamentals. One of the most common things i see in a novice indoor grow, is poor light placement. Im sure youve seen it or have had it yourself maybe in your earlier grows.. poorly rigged up systems, poor hoods, cheap bulbs, no reflective material in the room. For vertical hoods, i would recommend a double parabolic shaped with a dull white, aluminum or hammered finish. this evenly spreads light in a concentrated area and doesn't create too many hot spots. folds in hoods create hot spots. flat white paint, reflective mylar, white plastic... use it, get it as close to the light and around the area as possible, the closer it is to the light source the more light it will reflect back. Light Stress training, you can manipulate the growth of the plant to expose as much of the lower growth to light as possible. Methods including Sceen of green. or my recently dubbed "trail of green" where the plant is grown out horizontally, effectively turning every single chute and branch into a huge cola. all of these methods should be applied supplementary to the fundamental tips Video man has stated.

#5 HeadPawthead

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Posted 22 December 2007 - 06:38 PM

I think this is another myth that should be over come.
I don't believe cfl's produce less heat at all.
A watt is a watt.
When you produce/use a watt of electricity, heat is produced.

The benefit of using CFL's is that most growers simply use less watts than if they used there HID light.

You covered the light issue quite well. I would tell any newbie or private use grower to go with fluoros just because they are cheap and easy. They are also a good deal less massive and easier to hang. I use them almost exclusively because, as you pointed out, they are cooler to operate.



#6 green_nobody

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Posted 22 December 2007 - 07:40 PM

I think this is another myth that should be over come.
I don't believe cfl's produce less heat at all.
A watt is a watt.
When you produce/use a watt of electricity, heat is produced.

The benefit of using CFL's is that most growers simply use less watts than if they used there HID light.



i would be bit careful, a damn good CFL gets about 100 lum/W but a HPS gets 150 lum/W (as long it is bigger then 399W :hawkeye:) and a 400W can be use at less the 4" if aircooled and only a ft if un-cooled. you can't beat that with a 100lum/W CFL 2" away from the plant - there aren't enough lumen lost on that way and HPS wins.

and that CFLs are totally cold is a myst as well, the get so hot you can burn yourself touching one. and so they can burn, and will so, leafs too.
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#7 HeadPawthead

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Posted 22 December 2007 - 07:45 PM

Thanks green, glad we agree on this one, I had this argument with roseman, who told me to go grab my cfl in my hand, and hold it tightly.....which I did, and I cursed him...it burned my hand!

i would be bit careful, a damn good CFL gets about 100 lum/W but a HPS gets 150 lum/W (as long it is bigger then 399W :hawkeye:) and a 400W can be use at less the 4" if aircooled and only a ft if un-cooled. you can't beat that with a 100lum/W CFL 2" away from the plant - there aren't enough lumen lost on that way and HPS wins.

and that CFLs are totally cold is a myst as well, the get so hot you can burn yourself touching one. and so they can burn, and will so, leafs too.


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#8 Guest_nowherefast_*

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Posted 12 September 2008 - 03:15 PM

i agree as well, a cfl puts off plenty of heat as well. as said, grab one thats been on for 12 hours and if you dont burn your hand, youve got a burnt out bulb haha.

#9 Guest_micrich_*

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Posted 13 May 2009 - 08:47 AM

Thanks for the great info. micrich

#10 Guest_alldayeducation_*

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Posted 17 May 2009 - 11:25 PM

im learning an learning and learn thatnks to everybody at gp ...

#11 hcm2009

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Posted 02 November 2009 - 07:42 AM

I think this is another myth that should be over come.
I don't believe cfl's produce less heat at all.
A watt is a watt.
When you produce/use a watt of electricity, heat is produced.

The benefit of using CFL's is that most growers simply use less watts than if they used there HID light.


Thank you so much for the post. It's really informative!
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#12 spun420

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Posted 06 November 2009 - 01:15 AM

So new and have so many question i dont even no where to start 1. Puttin together a closet 10x10x5 using 1 400 w hps light (willthat be enough) 2. When should i go from the lil cups to the 3.5 gal (that what im usung for more space 3. For venting iwas planning on drilling two 1 3/4 in holes on each side of the closet and puttin a small computer fan to push the air out but leavin the othe hole open sorri for all the newbee ?'s but if dont ask u dont learn my 1st harvest is just a test see how i do meaning i didnt order the seeds and im usin bogus seeds not horrible ones just not the gr8est smoke i hopin to get a feel for everything so that the 2nd time around im more comfortable doing what needs to be done ...... Anyhew thanx
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#13 Guest_THEMIGHTYTONTO_*

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Posted 19 November 2009 - 09:15 PM

I think this is another myth that should be over come.
I don't believe cfl's produce less heat at all.
A watt is a watt.
When you produce/use a watt of electricity, heat is produced.

The benefit of using CFL's is that most growers simply use less watts than if they used there HID light.

Bullshit HSIC,
A CFL uses a percentage of the wattage.
yes its still hot, duh.
I does not however have a glowing flame of wire within it.

not alike most light sources

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Posted 19 November 2009 - 09:21 PM

I think this heat issue gets confused between cfls and flouro tubes... most people read flouro tubes are cool, and then read that compact flouros are flouros, and they assume they too will be cool. the only one that is actually cool to the touch is the tube, I have yet to find one that is hot while running no matter for how long. Having said that, the tubes are not as efficient in my opinion, they don't have the same bang for the buck that cfls have, so its a trade off, more heat for better light, or less heat for not as good light...

#15 The Corsican

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Posted 21 November 2009 - 05:12 PM

CFLs coil in on themselves and aren't as efficient at cooling themselves because of that fact. A long floro tube is cooler because they are straight and long. More surface area is exposed to air verses a cfl. -the Corsican.

#16 Raider_aod_2000

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Posted 22 November 2009 - 02:33 AM

Hello all, i have grown with HPS and MH from 400 watts all the way up to 1000 watts and yes even the 1,200 watt for the mega garden. I have recently started a new project and started to grow with 14 4 foot 54watt T5 fluorescent tubes and they work like champions. I have done one grow with them but did not take pictures the first time due to the fact that i wasnt part of a forum then and didnt need to log info to help people lol. I am currently taking pictures of this run and have them posted at http://www.greenpass...row-room-17107/ make sure to take a look at the light pictures. It took me 3 weeks to get to 12 inches in my veg state and when i switched to bloom they started to grow 1 inch per day if not a little more. I have done, tryed and have a lot of different setups and have seen a lot of different methods and i would have to say that growing with Non-compact fluorescent T5 tubes has been the best grow i have seen other than my industrial size grows where it is just easyer to use HPS and MH. All in all Fluorescent T5's is a smart way to go for a new grower. Oh and just to let everyone know heat produced from a light is not only dependant on the watt but also on the spectrum it is casting. A 6.5k produces more heat that a 3k, also when using multi lights it is easyer on the plant if it gets close to one or two of them than if you have a 400W light sitting right on top of it. One must remeber the rules of displacement, a 6 inche 600w light or 14 4 foot 54w lights. In the end the watts are spread out over a larger burn area allowing them to cool faster and to be easyer on close plants.
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#17 The Corsican

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Posted 22 November 2009 - 07:29 AM

Very interesting and informative post brother. Thanks, -the Corsican.

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Posted 06 December 2009 - 02:01 AM

wow! i have been to a few small and large grow sites and was thinking of starting myself but i had no idea it was so complicated and technical but the info i have learned will be very usefull to me so thanx everyone

#19 ImADoctor

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Posted 29 August 2010 - 08:34 AM

Awesome answers to the most popular question I could imagine from a grower. I'm excited to put it all to use. Thanx -Doc

#20 foxlikemad

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Posted 13 September 2010 - 08:02 PM

im not sure of this but its something i keep hearing from locals... alot of people around here are ditching hydro cloners for a simple small sectional planter tray with a clear topper and a very low heating mat under it... a couple have said they have a 90%-100% success rate with their clones. when i get that far i will do my own test and let ya know but considering im on my first grow we will see.
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#21 tigger

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Posted 14 June 2011 - 10:58 PM

WOW!! Thanks so much for taking the time to post all of that info! You guys rock!!!
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#22 fredflinstone

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Posted 31 March 2013 - 06:03 PM

wow! i have been to a few small and large grow sites and was thinking of starting myself but i had no idea it was so complicated and technical but the info i have learned will be very usefull to me so thanx everyone


its as hard or as easy as YOU want to make it!!!!!!!
i started off the easy route but like most things you do in life, you get better in time & want to improve what you,ve learnt, then gadgets,new techniques come in2 play & it gets wee bit harder, but master it you will ,i`ll guarantee you!!!
happy growing, & enjoy the experience!!




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