1 teaspoon/1.5 liter of fert is alot. i think a teaspoon gives you about 4-5 grams.
you should dilute a teaspoon to 1 gallon of water (3.7 liters)
if this is fert burn (from your soil) you might have compounded the problem.
you should see how your plant reacts before flushing.
if it gets worse, be prepared to flush.
epsom..add 1g/liter. ferts also 1g/L. this is the way i do it (varies by fert strength, ofcourse)
Liquid measurement... 1g of water = 1ml, so 500mls of water (50CL) is half a kilo...
1 Imperial gallon = 4.546 Liter
1 US Gallon is = 3.785 Liter
SO BE CAREFUL when measuring.
if the fert mix to water is 5ml then an 8% to 9% mix is what your looking at, when using US measurements, they are 20% less so a mix of 4ml is what your looking at.
The plant isn't responding to treatment. I've added approx 1 gram of Epsom salt to 1 liter of water and watered it as well as fed it through a spray/mist. Did that this morning. Leaves have all kinds of indications on them but I can't seem to make out what the trouble is. Its not fert burn and I can't figure out what it is. Any help would be appreciated.
Water... is is chlorinated by the water company? if so, you will need to draw water and allow it to stand for at least 24 hours for the chlorine to evaporate out the water. This is a problem where I live as the water company deliberately pump extra chlorine into the water which is why the water tastes like its come out of a swimming pool.
Too much food/feed in the water can actually burn the roots, roots should be a nice white colour and where too much nitrogen feed is added, the roots look a brown or yellow colour and will often be very short and small in size compared to a plant that is grown without feed.
You should not rule out parasites in the soil either, if you have something that you can take a soil core with, examine the soil for signs of little bugs.
THEN! Don't forget that if you have packed the grow medium down the roots can't develop as quickly as a lose packed pot AND pot drainage, people have various ideas on drainage, some put a large stone in the bottom and other put chunky gravel and other make up a perlite medium to grow in.
Finally, it could be the plant is not happy with its location, daft as it sounds, if its too cold it will show in the leaf.