I HAVE THE SAME THING GOING ON !!
You have a few issues going on here.
One is: your lights may be to close. See how your leaf’s are curling up. The leaf is trying to shade it self from the heat coming off the light.
2nd Here are a couple of pic’s of
" POTASSIUM "
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 color 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 color (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 color 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.
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. Sulfate of Potash, Sulfate of Potash Magnesia, Muriate of Potash, which are
medium absorption. FOXFARM GROW BIG HYDROPONIC 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.
Note: Wood Ashes, can make your ph go up a bit, so please monitor your ph when using it.
Now if you added to much chemical nutrients and or organics, (which is hard to burn your
plants when using organics) you need to flush the soil with plain water. You need to use
2 times as much water as the size of the pot, for example: If you have a 5 gallon pot and
need to flush it, you need to use 10 gallons of water to rinse out the soil good enough
to get rid of excessive nutrients.