What are some causes of slow plant growth?

Smokin Moose

Fallen Cannabis Warrior & Ex Moderator
Overwatering
Soil moisture that is not absorbed rapidly turns stagnant; the plant quickly uses up any oxygen within the water, then is unable to respire further, resulting in moisture low in o2. Pythium thrives in low-oxygen (anaerobic) conditions.

In short, overwatering will slowly suffocate your roots, preventing sufficient oxygen uptake by the roots, and ultimately causing root rot.

Soil with high bark content
This can cause a "bonsai" effect. The roots will not be able to grow through the bark, preferring to grow around the chunks of bark. This slows down root growth and most obviously plant growth. Ive encounter this recently; once transplanted into proper soil, they have shown remarkable recovery.

[Editor's note: bark is quite acidic, may may afect soil water pH]

Light deprivation
Although your plant may be receiving light, particular strains may require higher light levels than others. A recommended light level for full bud development is 50 watts/m2. Full sunlight is 100,000 lumens max.

Low nutrient strength
The plant is unable to acquire the necessary amounts of nutrients to sustain high growth rates. Large and mature plants can take higher nutrient strengths.

Nutrient strength is also related to the light intensity; plants under fluorescent lights usually require a lower nutrient concentration than under HIDs.

Nutrient lockup
Adding too much of a nutrient (ex. Magnesium) can "lockup" one or more nutrients, rendering them chemically unavailable to the plant. Nutrient lockup can occur at extreme pH ranges (ie. under 5.0, over 7.0).

Light spectrum
Light that does not contain enough red spectrum (too much blue)
Light spectrum can have a dramatic effect on plant growth, with different ligh frequencies affecting different photosynthetic processes within the leaf. Selecting a blue spectrum in a vegetative growth phase is preferred, with red spectrum in flowering.

pH
pH is too high or too low (ie. acidic soil. The plants come out as mutants).
Plants are unable to absorb nutrients, or in adequate quantities within certain pH ranges. Optimum pH varies with each medium. Hydroponics and aeroponics: 5.6-5.8. Soilless: 6.0-6.3 Soil: 6.5-7.0.

Many soilless mixtures can be fairly acidic, due to their high % bark content.

Low temperatures
Plant metabolism will decrease at low temperatures. Chemical reactions within the plant will take longer. Optimum plant growth often requires close temperature regulation; daytime temperatures between 25C and 30C are preferred. Differences in daytime and nighttime temps should not be dramatic, as this difference may shock the plant.

Low soil / medium temp
Evaporation from a medium (i.e. peat pots) tends to chill the medium quite a bit due to the evaporative cooling effect. As the peat pot warms, it draws moisture outward, the evap effect cools the peat (like sweating). New growers often make the mistake of adding excessive amounts of water, resulting in cold soil, poor root formation and slowed growth
 
sounds good thx :yummy:
but does it matter how far above the plant tops the light is? because im growing 4 plants and i had the light about 7 inches from the tops. i just moved the light up so now it stands a couple feet above the tops

yes, the intensity of the light drops off at the square of the distance... double the distance and get one quarter the light... so going from 7" to 24"... more than triple distance... now the plants are getting less than 1/9 of what they got before.
 
um..i didnt really read it all, so correct me if im wrong, but I didnt see anything covering root room. Cannabis will fill a 5 gallon bucket of soil full of roots in less than 3 weeks. I've already had to move to 20 gallon bins and only 6 weeks along. Just my input. And again, sorry if Im wrong...
 
um..i didnt really read it all, so correct me if im wrong, but I didnt see anything covering root room. Cannabis will fill a 5 gallon bucket of soil full of roots in less than 3 weeks. I've already had to move to 20 gallon bins and only 6 weeks along. Just my input. And again, sorry if Im wrong...

I'm starting my grow in 3 gal grow bags and was going to move to 5 or 7 gal on flower. Do you think they would fill out the 7 as well? 20 Gal seems huge, what size room do you have?
 
50'wx50'Lx10'H for my main "product" room, thats the Cindy99xLavenderxBubblegumxkali mist(almost 2 years in the making) and got some afblueberry thats in a 4'x4'x5' experiment grow...working on a journal for the small one entitled : AFBlueberry...its an experiment with 8 on 12 off technique...supposed to shave off a few weeks...we'll see...your welcome to follow...

New AFBlueberry Journal
 
just my personal opinion..here is what I do, i take my rockwool cuts and put them into keg cups,(the red ones with white inside) after about 2 weeks, around the arrival of the 3rd node, i transplant them into 20 gallon "bags" with moldable wiring around the lid to make a "pot". Thats all. lol. No nutes. Nothin but water, light, and soil. ORGANIC SOIL!!!! I usually pull about 114-122 grams dry per plant, for about the last 5 years. Been at it 15 alltogether. Your more than ok with 7 gallons, as most use 5 gallon buckets. But like i said...thats MY opinion...i'm not Rosenthal or Cervantes...GOOD LUCK FAMS!
 
yeah, i wish i had 50x50'. Man-o-man. when i played w/ cloning I was getting roots before I had pots empty from the previous grow. I put my clones in n e thing that would hold a gal of soil. Coffee cans, icecream buckets, old houseplant pots. I transplanted asap and am looking to a good harvest. I only grow what I smoke. to much trouble selling. Undesirables get to know who and what ur up to and I'm way to old to deal w/ a bunch of high kids. I don't drink or take any drugs. Pot is not a drug. Only to the gov. Its herb. It enhances things. Cookies, Candies, my fave, scrambled eggs. Just like parsley. Goes well in salad too. :rollit: eat it
 
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I have some Crop King seeds white widow growing in 100% coco and 2 of the 4 seem to be way behind the other 2 it is like they have just stopped. They all get the same amounts of everything. My ph of water is 5.5-5.8 but the runoff is like 7.6. From what I'm told in coco you don't worry about runoff ph. I can't figure it out they are all the same age and 2 are about ready for flower and 2 kook like they have about a month before they will be good to go. Any help would be great
 
^^^^anyone able to answer this... I'm growing in Coco as well and noticed that the growth is very slow
 
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I have some Crop King seeds white widow growing in 100% coco and 2 of the 4 seem to be way behind the other 2 it is like they have just stopped. They all get the same amounts of everything. My ph of water is 5.5-5.8 but the runoff is like 7.6. From what I'm told in coco you don't worry about runoff ph. I can't figure it out they are all the same age and 2 are about ready for flower and 2 kook like they have about a month before they will be good to go. Any help would be great
Phenom type happens with all plants from seed. Unless it's a clone even if its the same strain it will likely grow different on occasion.

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1st one is latest. ...the rest was one I harvest. .? Too early?
Give then a few days see if they swell more

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Im new to growing, why do you have chicken wire over the top of them? J

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Scrog. Screen of green. Basically trains the plants you try to get all of the bud sites at an even level so they all get large instead of one main cola.

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