HOW TO REDUCE STRETCH

im4satori

Well-Known Member
copy and paste from old unknown source from 10+ years back;


"Fine-tuning temperature and water for maximum quantity and quality.

Why waste light and electricity growing stem? Stretched-out plants are the bane of indoor growers. There are several ways to reduce internodal length and thus grow denser, more efficient buds.


Temperature control

The easiest and most under-used way to control internodal stretch is temperature control. Plant internodal length is directly related to the difference between day and night temperatures – the warmer your day cycle is as compared to your night cycle, the greater your internode length will be. The opposite also holds true; the closer your day and night temperatures, the shorter your internodes will be. Ever notice how as the warmer summer months approach, your plants begin to stretch? Part of this problem may lie in an overall hotter grow-room, but a larger factor is the increased difference between day and night temperatures.

Lets look at putting this to play in your grow room. Maximum temperatures should ideally never rise above 78.8°F, so you must do everything you can to prevent your room getting too hot (run lights at night, use exhaust fans, air conditioners, etc). An ideal temperature range is 75-77°F when the lights are on, and 71°F when the lights are off.

The temperature technique is most effective under a 12/12 light regime, which is ideal as this is when cannabis stretches the most. When the light cycle is brought to 12/12 we will raise the night temperature to the daytime level of 75-77°F. Space heaters on timers work well for this, and max/min type thermometers are ideal for
tracking temperatures.

It is during the first 2-3 weeks of the flower cycle that most strains begin to lengthen internodes, making it a very important time to control temperature, as this is when the framework for future colas is built. After this 2-3 week window we need to drop the night temperature back down to 71°F, as this is where the plant is happiest.


As floral development begins we need to keep in mind that the total size of your buds is determined largely by average daily temperature, provided it does not exceed optimal. So if you are letting your day temperatures drop below 75°F or your night drop below 71°F, you are costing yourself in overall weight and harvest.

Once your buds have reached optimal size and and you have begun the flushing period, you may consider dropping temperature down to 62-66 F for the final week or two. This drop in temperature triggers anthocyanin production, which intensifies the color of the floral clusters and makes for a showier bud, especially with "purple" varieties. This final temperature change is not always feasible and can be omitted.

For extreme height control you may even use warmer night temperature than day, but be very careful when running settings like this, as even a zero difference between night and day temperatures will lead to leaf chlorosis (yellowing) after 2-3 weeks.

Some things you will notice while using this technique are a change in the leaf angle, upwards during warm days and downwards during warm nights. There is also the chlorosis if this is done for too long. Neither of these symptoms is nutrient related and will fix themselves when the temperature is changed back.


Moisture and conductivity

Whether you're growing hydro or in soil, the electrical conductivity (EC) and moisture of your medium are two key elements that should be manipulated to meet your needs. Both of these factors are controlling the same thing; the ability of a plant to uptake water and nutrients from the growth medium. (EC measures the level of fertilizer salts in the water.)

A plant grows by first dividing cells then expanding them, and in order to do this it requires water. By limiting the amount of water available to a plant you limit the expansion of cells. This can work for you by keeping your internodes close together, or against you by limiting bud growth. Both the amount of water you give your plants and the EC at which you grow them control the uptake of water.

A plant's roots act much like a pump, using osmotic pressure to move water into the plant. In order for this to work there must be a larger concentration of fertilizer salts in the plant's roots than in the soil or hydroponic solution, so when the medium's level of salt rises above the roots', the plant will wilt. Raising the salt level in the medium closer to that which is in the roots limits the water availability just the same as if we had provided less water.

During the vegetative stage we want our plants to form very tight internodes, especially under artificial lighting. By allowing the EC to drop below ideal during this stage we are wasting valuable space growing stem instead of bud. Most marijuana strains are happiest when grown at an EC of between 1.5 and 1.8, but different strains have different preferences. Try growing one of your plants using straight water for a week or so, you will see the internode length stretch dramatically compared to the ones on a regular fertilizer regime.


Hydroponic tomato growers sometimes will grow their transplants at extremely high EC's (up to 6 EC!) in order to get really nice stocky production plants. Please note that when doing this they use special nutrient formulas designed for this purpose, most of which have potassium to nitrogen ratios of 4:1, much higher than normal, as too much nitrate at this high an EC will easily damage a plant.

(Try this formula if you're interested: calcium nitrate 7 grams, potassium nitrate 0.095 grams, potassium sulphate 9.25 grams, mono potassium phosphate 2.2 gram, magnesium sulphate 5 grams, micromix .02 grams. Slowly raise your EC during veg stage, I would not recommend going above 3 or 4 EC. This is experimental! Do not try on all of your plants at once until you are sure your strain can handle it. All of these ingredients should be available at your local hydroponics store, it is usually called "six pack formula". Be sure to bring your EC back down once you enter floral stage, by the time tufts of pistils are visible you want to be at your ideal EC of 1.5-1.8.)

Try not to change the EC too quickly as a sharp drop can cause root damage. This also goes during your final flushing period when you want to eliminate all fertilizer from the medium – lower the EC over a couple of days, as the sudden change in salt level will harm the roots.

When growing hydroponically, the only way of manipulating water availability is with the EC, while in soil we may also use the moisture level of the medium to the same ends. Many growers are under the mistaken impression that the EC and pH of their nutrient solution remains the same when applied to the soil. This in not the case, and you must test the soil in order to have a true
picture.


To test your soil, take a sample from the center of the root zone at the side of the pot (don't worry the torn roots will be fine). Mix the soil with 2 equal parts distilled water and let sit for 20 minutes. Once the time is up take an EC reading and multiply this number by 2.4 (this takes into account the dilution and the pore space factor) this will give you an accurate picture of the EC the roots are actually being exposed to. The pH should also be checked at this time. It is not feasible in soil to maintain an exact EC at all times, what we need to try and avoid is EC's climbing much above what we want and plants going for long periods with very low EC's.

A frequent mistake marijuana growers make is over-emphasizing the need for a plant grown in soil to dry out completely between waterings. Cannabis does like dry feet but this simply means that the root zone must not be kept extremely wet at all times. Keep in mind that if the soil has an EC of 1.8 and then dries out completely the amount of salt remains the same, causing the EC to double or more.

As a general rule, during the vegetative stage you should keep your plants a little on the drier side as this will restrict cell elongation, creating a shorter noded plant structure capable of creating a dense bud cluster in the floral stage. (Unless of course you are using the high EC method described above, in this case you must not let your soil get too dry because of the increased fertilizer level you will create.) Maintain this level of moisture into the first 14 to 20 days of 12/12 to minimize internode stretch.

As soon as early flowering begins you need to increase soil moisture to a nice evenly moist (not soaked) level to maximize bud expansion. Growing marijuana too dry during this stage will adversely affect your overall yield, as will having too high an EC in the medium.

In these times of government oppression we must make the most efficient use of available growing space in order to produce the copious amounts of cannabis necessary to overflow the boundaries placed upon us. Control your cannabis!"
 
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im4satori

Well-Known Member
heres some more info on the day night temps

again its copy and paste from old unknown source from 10 years ago;


Day-Night Temperatures
For the majority of flowering and fruiting plants produced hydroponically, plant growth and flowering will be optimal under conditions where the night temperature is lower than the day temperature. Most plant species exhibit these 'Diurnal rhythms' where certain plant process such as the rate of growth of the flower buds, stomata opening, discharge of perfume from flowers, cell division and metabolic activity, occur more rapidly at a certain time within a 24 hour period. For example, photosynthesis in most plants is known to reach a maximum just before noon, and cell division also seems to always reach a maximum just before dawn. Many species flower or grow well only when temperatures during the part of the diurnal cycle that normally comes at night are lower than temperatures during the day. Also light given during the normal night period may actually inhibit some plant processes.



Plants such as tomatoes seem to be particularly sensitive to the alternation in temperature between day and night: they produce more flowers when night temperatures are lower than day temperatures - this effect in plants is called 'Thermoperiodism', and is common amongst many plant species. Pepper plants also require lower night than day temperatures for good production, it has been found that many more buds on pepper plants will actually develop into open flowers when night temperatures are at least 6 C(11F) lower than day temperatures. Where day and night temperatures remain at similar levels on a long term basis, flowering and fruiting can be adversely affected, particularly where temperatures are warm. Bud, flower and fruitlet abscission is much more common on crops which do not receive lower night temperatures and this often limits production of crops such as tomatoes and peppers under tropical conditions.



Night temperatures for most plants are optimal at around 18 C (65F) too 24 C(75F) lower than day temperatures, provided day temperatures are held at optimal levels for photosynthesis. At night, where the 'sinks' which receive the assimilates (sugars) produced via photosynthesis, become cooler, transport of sugars into these is promoted. 'Sinks' on most plants are the developing flower buds, flowers and fruit which have the greatest affinity for the sugars produced by the plant. The 'Source' is the producer of the assimilates - usually the leaves, but sometimes also the stem in some plant species. So cooler 'sinks' get more assimilate pumped into them at night than if they remained as warm as they were during the day light hours.



Apart from the physiological effects on plant growth and flower development, having a lower night temperature setting has other beneficial effects on plant processes. Firstly root pressure is greater at night under cooler conditions - this increases the pressure in the xylem vessels, so that calcium and other plant growth compounds which are carried in the xylem stream are forced out to the leaf tips and into developing buds, flowers and fruits. This turgor pressure is often essential in the prevention of tip burn as it ensures calcium is carried to the very edges of the leaves. Often, this root or xylem pressure can be seen in the form of 'guttation' which are visible droplets of water which can be seen at the tips of leaves on plants in the early morning. It is this root or xylem pressure which also acts to 'pump up' the plant during the cooler night temperatures particularly after a day when transpiration rates and warm temperatures have resulted in some wilting and loss of turgour.
Maintaining cooler night temperatures also ensures that plant respiration does not occur at too greater rate. Respiration uses up valuable assimilates and the rate of respiration increases rapidly with temperature. Under very warm night temperature conditions, night respiration can burn nearly as much assimilate as has been produced via photosynthesis and can severely limit plant growth.
 

SouthCross

Well-Known Member
That's wonderful....Answered some of questions. I've been running them too dry. It's caused a lot fertilizer issues. Something told me to increase the watering. This information has verified it. I'm gonna hook this up.

Thank You.
 

im4satori

Well-Known Member
I should say

I don't subscribe to the high EC feeding and I feel genetics plays the biggest role in plant structure

but all these things do make some difference

I personally use the day night swing method or lack there of and it does make a difference
 

im4satori

Well-Known Member
Do your outdoor plants stretch more without a controlled environment?
ive honestly never had the nerve to grow pot outside ..lol

but I don't think stretch is as much of an issue for outdoor where you have unrestricted space and height and natural light penetration

at that point you get what your genetics are and what mother nature throws you

but these are assumptions since I have no personal experience with outdoor grows
 

jarvild

Well-Known Member
Just up for a honest discussion on this subject. When my outdoor plants go into flower my temp ranges can go anywhere from 15 to 20+ degrees. Indoors the change is 7 degrees from day to night.
 

SouthCross

Well-Known Member
Just up for a honest discussion on this subject. When my outdoor plants go into flower my temp ranges can go anywhere from 15 to 20+ degrees. Indoors the change is 7 degrees from day to night.
I've grown males outside with a drop to 43°f over several days. The high during the day was in the high 60's. It flourished.

If I replicated the same conditions in a synthetic environment. I would have killed it.
 

im4satori

Well-Known Member
Just up for a honest discussion on this subject. When my outdoor plants go into flower my temp ranges can go anywhere from 15 to 20+ degrees. Indoors the change is 7 degrees from day to night.
it would be interesting to grow 2 clones from the same donor

one in and one out in the same soil and log the temps of each

keep the indoor grow day night temps the same and let mother nature do its thing outside and see the difference in gowth but with having natural light vs artificial light im not sure you can really make a true comparison

if you had two indoor flower rooms you could do a side by side...
 

im4satori

Well-Known Member
I've grown males outside with a drop to 43°f over several days. The high during the day was in the high 60's. It flourished.

If I replicated the same conditions in a synthetic environment. I would have killed it.
I had the night time heater go out on me while I was away for a couple days on an indoor during the winter

temps dropped to 40 a couple nights in a row, it didn't kill them but it fucked them all up ... pitiful yields and stretched out scraggling plants
 

GroErr

Well-Known Member
Contrary to the suggestions on the article but related to stretch management is negative DIF, or having the dark period at or above the temps in the light period. It's said that plants stretch less if the temp difference is the same or higher during lights off. I tested a few rounds last summer and this seems to hold true for MJ. Stretch was reduced from running my normal temp swings. it's difficult to do this other than in summer but worth a try if you can swing it.

A more practical approach which seems to have merit is temperature differences in your lights (expressed in Kelvin) between veg and flower seem to have an effect on stretch. I've validated this also using different light sources and the greater the difference, the greater the stretch seems to hold true. So, providing them with a "cooler" light source for the first couple of weeks through the stretch can help reduce stretch or vice versa if you want more stretch. This can be tested/done by running MH higher kelvin lights or similar using COBs through the stretch period. I've just re-validated this when I recently switched my veg lights to 5700k white COBs vs. blurple LED panels, then flowered under my 3500k lights in the flower room. Noticing more stretch than previous runs.
 

SouthCross

Well-Known Member
Contrary to the suggestions on the article but related to stretch management is negative DIF, or having the dark period at or above the temps in the light period. It's said that plants stretch less if the temp difference is the same or higher during lights off. I tested a few rounds last summer and this seems to hold true for MJ. Stretch was reduced from running my normal temp swings. it's difficult to do this other than in summer but worth a try if you can swing it.

A more practical approach which seems to have merit is temperature differences in your lights (expressed in Kelvin) between veg and flower seem to have an effect on stretch. I've validated this also using different light sources and the greater the difference, the greater the stretch seems to hold true. So, providing them with a "cooler" light source for the first couple of weeks through the stretch can help reduce stretch or vice versa if you want more stretch. This can be tested/done by running MH higher kelvin lights or similar using COBs through the stretch period. I've just re-validated this when I recently switched my veg lights to 5700k white COBs vs. blurple LED panels, then flowered under my 3500k lights in the flower room. Noticing more stretch than previous runs.
I noticed that too. Previous grow was pink LED. Finished height was around 22". Under a mix of 3000 and 3500k. The same strain grew well past 40". The yields won't compare. The taller plants have at least triple the bud.
 

im4satori

Well-Known Member
Contrary to the suggestions on the article but related to stretch management is negative DIF, or having the dark period at or above the temps in the light period. It's said that plants stretch less if the temp difference is the same or higher during lights off. I tested a few rounds last summer and this seems to hold true for MJ. Stretch was reduced from running my normal temp swings. it's difficult to do this other than in summer but worth a try if you can swing it.

A more practical approach which seems to have merit is temperature differences in your lights (expressed in Kelvin) between veg and flower seem to have an effect on stretch. I've validated this also using different light sources and the greater the difference, the greater the stretch seems to hold true. So, providing them with a "cooler" light source for the first couple of weeks through the stretch can help reduce stretch or vice versa if you want more stretch. This can be tested/done by running MH higher kelvin lights or similar using COBs through the stretch period. I've just re-validated this when I recently switched my veg lights to 5700k white COBs vs. blurple LED panels, then flowered under my 3500k lights in the flower room. Noticing more stretch than previous runs.
for sure the lighting type can make a difference also

I tune my dehumidifier up or down
if I set it at 40% humidity during the night itll get real warm or 60% if I need it to run less

in the winter its hard cuz the humidity is often already low (unless your in a basement)
 

GroErr

Well-Known Member
I noticed that too. Previous grow was pink LED. Finished height was around 22". Under a mix of 3000 and 3500k. The same strain grew well past 40". The yields won't compare. The taller plants have at least triple the bud.
Yeah I noticed it when I originally switched from blurple panels (for both veg + flower) to CMH (3100k) I had huge stretch (also more than doubled my yields - lol). Then I switched to 3500k COBs and from blurples in veg, the stretch was less/normal. More recently I switched my veg lights from blurples to 5700k white COBs and noticed a swing back to more significant stretch. Can be good or bad depending on the situation. Under LED's in veg I find the nodes are really tight so I don't mind some extra stretch but it could be detrimental if your room height is limited or running plants with large internodal spacing.
 
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