Potassium Deficiency?

I belive I may have a potassium deficiency. I was reading this indoor gardening book I have and I was looking at the pictures and they kind of looked like my plants. My stems don't seem to be weak but my leaves are curling up on the edges of some of my plants. Any ideas of what it might be?

The pictures below are K deficiency, if your sure you have it and your plants look like the pics then this should help ...



Potassium (K) Mobile Element and Macro Element

Potassium plays a big role as well. Having good amounts of potassium in your plants helps in having sturdy and thick stems, disease-resistance, water respiration, as well aids in photosynthesis. Potassium is also found in the whole plant. It is necessary for all activities having to do with water transportation. Potassium is necessary for all stages of growth, especially important in the development of Buds.

Having to little of Potassium in your plants causes the plants leaves to show retarded growth and show a scorched tip and edges around the leaves. Plants may stretch and your branches can be easily broken or weak. Don’t get this deficiency confused with iron, because it almost acts like iron but to tell the difference in the two is: for potassium the tips of the leaves curl and the edges burn and die. Older leaves may show a red colour and leaves could curl upwards. Dead patches (Necrosis) can happen on the margins of larger fan leaves thus, the leaves will eventually die off and turn brown. The Older leaves will show different patches of colour (mottle) and turn yellow between the veins, following by whole leaves that turn dark yellow and die. The plants overall growth slows down, mostly when they are in vegetative stage. To little amount of potassium also slows the growth of buds during flowering stages. Dark edges will appear around the edges of the leaf when the deficiency is starting to happen. When your Relative humidity is low, you can almost bet your going to soon get a potassium deficiency from your plants perspiration.
Potassium can get poorly absorbed when having too much Calcium or ammonium nitrogen, and maybe cold weather. Having to much sodium (Na) causes potassium to be displaced. SO keep those in mind… Parts affected by a Potassium Deficiency are: older leaves and leaf margins.


When you have too much Potassium in your soil, it can lead to big troubles, like salt damage and acid fixation of the root system, as well as too much potassium can cause a calcium deficiency. Your fan leaves will show like a light to a dark yellow to whitish colour in between the veins. Due to a molecular imbalance, potassium toxicity can cause a reduced uptake and lead to the deficiencies of Mg, and in some cases, Ca. Also leads to the other nutrients to not be absorbed properly leading to lots of other deficiency such as: magnesium, manganese, zinc and iron and can cause problems with calcium as well.



Problems with Potassium being locked out by PH troubles
Soils with excessive Leeching and High ph soils and or water. Soils that are potassium fixated. An excess of kitchen salts (sodium) in the root system/enviroment.


Soil

Potassium gets locked out of soil growing at ph levels of 4.0-5.5
Potassium is absorbed best in soil at a ph level of 6.0-9.5. (Wouldn’t recommend having a ph of over 7.0 in soil) anything out of the ranges listed will contribute to a Potassium deficiency.


Hydro and Soil less Mediums

Potassium gets locked out of Hydro and Soil less Mediums at ph levels of 4.0-4.5, 6.0-6.5.
Potassium is absorbed best in Hydro and Soil less Mediums at ph levels of 4.7-5.3, 6.7-8.5. (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a potassium deficiency.



Solution to fixing a Potassium deficiency
Any Chemical/Organic nutrients that have potassium in them will fix a potassium deficiency. Again Peters All Purpose plant food 20-20-20, will cure the potassium deficiency , Miracle grow Tomato plant food, Miracle grow All purpose plant food.( Only mixing at ½ strength when using chemical nutrients, or it will cause nutrient burn!) Some other supplements of potassium are: Wood ashes, which are fast absorption, Kelp Meal, which is medium absorption, Greensand, which is slow absorption, granite dust, which is slow absorption. Sulphate of Potash, Sulphate of Potash Magnesia, Muriate of Potash, which are medium absorption. FOXFARM GROW BIG HYDROPONICS CONCENTRATE, which is fast absorption. (FFGB can bring your ph down as well) Earth Juice Meta-K, which is fast acting. (Can bring down your ph as well) Leaves will never recover, but the plant will show recovery after about 4 to 5 days when using a fast acting nutrient.

really need some pics and info man, how old, growing medium,lights, air????? water , ph.

I also forgot to mention its only happening on my biggest plant.

how close to the light is the plant??

I just measured from the top of the plant to the light its about 28 inches or so.

Does anyone know the problem?

Looks to me like they are just curling a bit from the heat. What is the temp in the room? How is your ventilation? I do not see any signs of a nut def. but there are mmuch better eyes than mine on this board. Can you take a pic without the HPS on? We need more info on the grow itself. Light wattage and type, grow medium, nuts, conatiner size, strain if know, age of plants, and room or closet size.

I think I have both a potassium issue as well as a magnesium issue. The potassium I think is from my low humidity and the magnesium I can't figure out. I have wrinkling fan leaves, curling upwards sort of like they are inside out. Older leaves are turning brown and yellow on the tips and now the new growth on some of the plants is growing in mottled yellow. The only thing I can figure is that my pH is off. I'm growing in soilless mix so what should the range be? More similar to hydro than to soil, right? Anyone have any ideas? Here are pics of each of the problems.