Stop using a water spray as it is probably just leaching the leaves out further with that......you can add ST at ONE DROP a gallon for seedlings......warning....will lower ph a bit so check. Water small amounts.....not necessarrily to runoff, just get the medium damp/wet and not have runoff each time...... lots of runoff means you could be flushing the good stuff straight though as I found it from personal experience . Stinky may suggest some sort of foliar spray with nutes but I wouldn't really know how to give instructions for that or even if it's needed because I'm just not knowledgable in enough in soil to say.
If you can spare the $8-10 ish dollar to buy a nice big bag of Happy Frog soil for your plant and it will reward both you and the plant with good soil ph and some good nutes perfect for seedlings along with great growing for quite a while and make your life a lot easier at the same time. A quality soil (MAKE SURE ITS THE RIGHT KIND FOR THE JOB! YOU WANT!) will save you both dollars for extras and give you MANY less headaches with playing around with a lousy soil like Miracle Grow and pay for it self MANY TIMES OVER per grow.
Worth every penny.