fan leaves turning into claws...HELP ME!!!

what is your pH?

 

This is originally from uncle ben. Just posting it to help you out.

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

Quite often I hear groans from folks having leaf problems -> “Help, myleaves are cupping and the leaf edges are turning brown!”, or, “My plant's leaftips are curling down and turning black ....what's wrong?” Unless insect damagehas occurred or the plant is suffering from a severe case of calciumdeficiency, the plant is trying to tell you that it is water stressed. It'shard 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 servesto make matters worse by promoting further decline. I'll try to cover some ofthe more common causes that can induce these common symptoms and try to offer afew simple solutions. The ultimate and correct solution is in the hands of thegrower.

1. Over-fertilizing - the most common cause of leaf cupping aka leaf marginrolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of toomuch plant food in relationship to factors such as plant size, vigor and rateof growth. The first unit of a plant to show moisture stress is the leaf at itsmargins and/or tips, reflected by margin rolling (cupping) or burning.Sometimes copper colored necrotic spots show in the leaf also. A hard, crispyfeel to the leaf frequently occurs as well, as opposed to a soft and cool feelof a happy leaf. When you have a high concentration of salts in solution (or inthe 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 tofix the ppm imbalance. IOW, this is a natural, osmotic response that serves toequalize salinity levels on both sides of the root's epidermal gradient. Backoff on the amount and/or frequency of plant food. Too much plant food can alsoburn the roots, especially the sensitive root tips and hairs, which thencreates another set of problems such as nutrient deficiencies. A note for thebio folks - as soil dries, the concentration of the remaining salts risesfurther exacerbating the problem. Leach (flush) your pots once in a while toget rid of excess salts.

2. High Heat - the plant is losing water via it's leaves faster than what canbe replaced by the root system. The leaf responds by leaf margin cupping orrolling (up or down) in order to conserve moisture. A good example is reflectedby 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 willtake on a dull, greyish-green appearance. Upon sunrise when moisture levelshave returned to normal, the leaf blade will be flat. Lower the heat andconcentrate on developing a large, robust root system by practicing sound plantculture. An efficient and effective root system will go a long way to preventheat induced leaf dessication and leaf margin curling by supplying sufficientmoisture for good plant health. One short episode of high heat is enough topermanently destroy leaf tissue and cause a general decline in the leavesaffected, which often occurs to leaves found at the top of the plant locatednear HID lamps. The damaged leaf (usually) does not recover, no matter what youdo. Bummer in the summer. One can only look to new growth for indications thatthe problem has been corrected.

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

4. Overwatering - this practice only serves to weaken the root system bydepriving the roots of proper gas exchange. IOW, the roots are not gettingenough oxygen which creates an anerobic condition causing root decline and rootrot with the end result showing up as leaf stress, stunted growth, and insevere cases, death. <gasp!> Alot of times folks think the plant is notgetting enough plant food (which it can't under such adverse conditions), theyadd 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 ofadequate moisture, but carbohydrate production has been greatly compromised(screwed up). Step up the watering frequency, and if need be, organic growersmay need to soak the pot from the bottom up until moisture levels reach an evenconsistency throughout the medium especially with mixes that are heavy in peat.If severe, a little surfactant (liquid Ivory dish soap) added to the drenchwill help return the organics back to a normal moisture retentive state. If thepot feels light to the lift - it's time to water. Don't wait until the soilpulls away from the sides of the pot or leaves droop before you water.

Happy gardening,
Uncle Ben

Thanks
ODP