Maybe you should try a little variation of what oranje posted before you jump in with both feet partially based on my limited experience with a different product.
Fill your container 1/2 way with the Sensi soil, put an inch or two of standard potting soil on top of that. Put in your seedling and back fill around it with the standard potting soil. Give it couple of days and see what happens.
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Sensi Soil
INGREDIENTS
Coconut Coir Fiber, Coarse Sphagnum Peat Moss, Premium Worm Castings, Bokashi, Whole Cane Sugar, Dolomite Lime (for pH adjustment), Yucca (natural wetting agent), Premium Microbial Inoculum and Fertilizer