Plant Moisture Stress - Symptoms and Solutions

John Rollwan

Well-Known Member
I made a post in a different listing, i was told this is heat stress, temp 75-80 humidity 55-59 blue dream, mh 600 w, 4x4, coco with 30% perlite, watering every 4 hours week 5 since seed. i can show another photo, inbetween the veins its bublling and turning yellow on other leaves, two different blue dream strains in this tent, only one showing any stress....any help would be appreciated.
Looks to be some heat stress. I run 62F at night 74F in day. They love it. The cool time at night booms tri development.
 

Carolireland

New Member
PLANT MOISTURE STRESS - symptoms and solutions (revised Jan. 12, 2009)

Quite often I hear groans from folks having leaf problems -> “Help, my leaves are cupping and the leaf edges are turning brown!”, or, “My plant's leaf tips are curling down and turning black ....what's wrong?” Unless insect damage has occurred or the plant is suffering from a severe case of calcium deficiency, the plant is trying to tell you that it is water stressed. It's hard to tell *exactly* what the culprit is, and unfortunately the “solution” the grower chooses many times is not the right one. A mis-diagnosis only serves to make matters worse by promoting further decline. I’ll try to cover some of the more common causes that can induce these common symptoms and try to offer a few simple solutions. The ultimate and correct solution is in the hands of the grower.

1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant size, vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. Sometimes copper colored necrotic spots show in the leaf also. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plant’s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the root’s epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips and hairs, which then creates another set of problems such as nutrient deficiencies. A note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem. Leach (flush) your pots once in a while to get rid of excess salts.

2. High Heat - the plant is losing water via it’s leaves faster than what can be replaced by the root system. The leaf responds by leaf margin cupping or rolling (up or down) in order to conserve moisture. A good example is reflected by the appearance of broad-bladed turf grass on a hot summer day, high noon, with low soil moisture levels - the leaf blade will roll in and the grass will take on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat and concentrate on developing a large, robust root system by practicing sound plant culture. An efficient and effective root system will go a long way to prevent heat induced leaf dessication and leaf margin curling by supplying sufficient moisture for good plant health. One short episode of high heat is enough to permanently destroy leaf tissue and cause a general decline in the leaves affected, which often occurs to leaves found at the top of the plant located near HID lamps. The damaged leaf (usually) does not recover, no matter what you do. Bummer in the summer. One can only look to new growth for indications that the problem has been corrected.

3. High Light - yes, it’s true, you can give our faves too much light. Cannabis does not receive full sun from sunrise to sunset in its natural state. It is shaded or given reduced light levels because of adjacent plant material, cloudy conditions, rain, debris and dust collection on the leaf surface, twilight periods of early morning and late afternoon, and light intensity changes caused by a change in the seasons. Too much light mainly serves to bleach out and destroy chlorophyll as opposed to causing leaf cupping, but it often goes hand-in-hand with high heat for indoor growers. Again, back off on the light and concentrate on developing/maintaining an efficient and robust root system. Keep in mind that all but equatorial material receive less light during flowering than during the vegetative stage.

4. Overwatering - this practice only serves to weaken the root system by depriving the roots of proper gas exchange. IOW, the roots are not getting enough oxygen which creates an anerobic condition causing root decline and root rot with the end result showing up as leaf stress, stunted growth, and in severe cases, death. <gasp!> Alot of times folks think the plant is not getting enough plant food (which it can't under such adverse conditions), they add more nutes for a "curative", and just add insult to injury.

5. Underwatering - not only is the plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic growers may need to soak the pot from the bottom up until moisture levels reach an even consistency throughout the medium especially with mixes that are heavy in peat. If severe, a little surfactant (liquid Ivory dish soap) added to the drench will help return the organics back to a normal moisture retentive state. If the pot feels light to the lift - it&#8217;s time to water. Don&#8217;t wait until the soil pulls away from the sides of the pot or leaves droop before you water.

Happy gardening,
Uncle Ben

What is IOW? or what does it mean?
 
Marijuana plants require adequate moisture to grow healthy and produce high-quality buds. However, overwatering or underwatering can cause stress to the plants, which can lead to various symptoms that affect plant health and yield.

Overwatering Symptoms:

Yellow leaves - It can cause yellow leaves, especially on the lower part of the plant. The leaves may also become soft and droopy.
Slow growth - It also cause slow growth as roots struggle to absorb nutrients and oxygen from the waterlogged soil.
Root rot - Overwatering can lead to root rot, which can cause the roots to turn brown or black and become mushy. This can lead to plant death if not treated promptly.
Mold and Mildew - Overwatering can also create a damp environment that promotes the growth of mold and mildew, which can affect the plant's health and yield.

Solutions to Overwatering:

Adjust watering schedule - Reduce the frequency of watering and allow the soil to dry out between waterings. Make sure to water the plants only when the top inch of soil is dry.
Improve drainage - Improve the drainage of the soil by adding perlite, vermiculite, or sand to the soil mix.

Moisture stress can have a significant impact on the health and yield of marijuana plants. By understanding the symptoms and solutions of overwatering and underwatering, you can take steps to ensure that your plants receive the right amount of moisture to grow healthy and produce high-quality buds.
 

Wolflaika11

New Member
Do you have any recommendations for how much to feed a seedling? How often? And what kind of fertilizer? After posting my plant photos and reading your post, I think that may be the issue with my lil guy (see photo), but not sure how to solve
 

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sh0wtime

Well-Known Member
I've noticed with my seedlings that they started to get those purple stems when they had too much water too early.
I did let 'em dry out for a couple of days and they went back to beautiful green.

Wolf: I've put them in lightmix and just fed 'em with rhizotonic until the fert ran out.
No NPK needed at all, when the nutrients that were in the soil ran out my bottom leafs went a bit bright and one plant became rusty spots, I added some cal mag and they were happy again. Couple days after I repotted.

No biggie...
 

Mr Lizard

Well-Known Member
PLANT MOISTURE STRESS - symptoms and solutions (revised Jan. 12, 2009)

Quite often I hear groans from folks having leaf problems -> &#8220;Help, my leaves are cupping and the leaf edges are turning brown!&#8221;, or, &#8220;My plant's leaf tips are curling down and turning black ....what's wrong?&#8221; Unless insect damage has occurred or the plant is suffering from a severe case of calcium deficiency, the plant is trying to tell you that it is water stressed. It's hard to tell *exactly* what the culprit is, and unfortunately the &#8220;solution&#8221; the grower chooses many times is not the right one. A mis-diagnosis only serves to make matters worse by promoting further decline. I&#8217;ll try to cover some of the more common causes that can induce these common symptoms and try to offer a few simple solutions. The ultimate and correct solution is in the hands of the grower.

1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant size, vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. Sometimes copper colored necrotic spots show in the leaf also. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plant&#8217;s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the root&#8217;s epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips and hairs, which then creates another set of problems such as nutrient deficiencies. A note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem. Leach (flush) your pots once in a while to get rid of excess salts.

2. High Heat - the plant is losing water via it&#8217;s leaves faster than what can be replaced by the root system. The leaf responds by leaf margin cupping or rolling (up or down) in order to conserve moisture. A good example is reflected by the appearance of broad-bladed turf grass on a hot summer day, high noon, with low soil moisture levels - the leaf blade will roll in and the grass will take on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat and concentrate on developing a large, robust root system by practicing sound plant culture. An efficient and effective root system will go a long way to prevent heat induced leaf dessication and leaf margin curling by supplying sufficient moisture for good plant health. One short episode of high heat is enough to permanently destroy leaf tissue and cause a general decline in the leaves affected, which often occurs to leaves found at the top of the plant located near HID lamps. The damaged leaf (usually) does not recover, no matter what you do. Bummer in the summer. One can only look to new growth for indications that the problem has been corrected.

3. High Light - yes, it&#8217;s true, you can give our faves too much light. Cannabis does not receive full sun from sunrise to sunset in its natural state. It is shaded or given reduced light levels because of adjacent plant material, cloudy conditions, rain, debris and dust collection on the leaf surface, twilight periods of early morning and late afternoon, and light intensity changes caused by a change in the seasons. Too much light mainly serves to bleach out and destroy chlorophyll as opposed to causing leaf cupping, but it often goes hand-in-hand with high heat for indoor growers. Again, back off on the light and concentrate on developing/maintaining an efficient and robust root system. Keep in mind that all but equatorial material receive less light during flowering than during the vegetative stage.

4. Overwatering - this practice only serves to weaken the root system by depriving the roots of proper gas exchange. IOW, the roots are not getting enough oxygen which creates an anerobic condition causing root decline and root rot with the end result showing up as leaf stress, stunted growth, and in severe cases, death. <gasp!> Alot of times folks think the plant is not getting enough plant food (which it can't under such adverse conditions), they add more nutes for a "curative", and just add insult to injury.

5. Underwatering - not only is the plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic growers may need to soak the pot from the bottom up until moisture levels reach an even consistency throughout the medium especially with mixes that are heavy in peat. If severe, a little surfactant (liquid Ivory dish soap) added to the drench will help return the organics back to a normal moisture retentive state. If the pot feels light to the lift - it&#8217;s time to water. Don&#8217;t wait until the soil pulls away from the sides of the pot or leaves droop before you water.

Happy gardening,
Uncle Ben
I had a weird one where my buds were looking great but I had used a cheap timer. They started growing sticks or branches out of the flowers. I finally realised that the F***ing timer wasn't shutting off. After 3 days of replacing it the extra growth has started turning into healthy extra premature flowers. Some of these were up to 8"-10" long. Also can someone tell me the difference between 2.0.0.0, 4.0.0.0 and 7.0.0.0 CalMag? It has me scratching my head
 

Mr Lizard

Well-Known Member
Do you have any recommendations for how much to feed a seedling? How often? And what kind of fertilizer? After posting my plant photos and reading your post, I think that may be the issue with my lil guy (see photo), but not sure how to solve
I start my cuttings on 1.5ml of A&B per 3 litres of water. Also using a light foliar spray. Then slowly increase it. For established seedlings in soil I use 1/4 strength until they get to about 8" with good healthy foliage.
 
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