Please help me diagnose my Hybrid Willows (Austree)!

I bought approximately 50 Hybrid Willows about 5 weeks ago. I set them into water filled jars at about 2/3 depth (6 inches) for about two weeks. Then transferred them to 3 gallon buckets with "Sta-Green 2-cu ft Tree and Shrub Soil With Fertilizer". It contains:
0.04% Ammoniacal Nitrogen
0.03% Nitrate Nitrogen
0.02% Urea Nitrogen
0.06% Phosphate
0.05% Soluble Potash
sphagnum moss, ground dolomitic limestone (ph adjusted), wetting agent, and either reed-sedge peat or composted pine bark.

I added "Pennington UltraGreen All Purpose Food 10-10-10"

Since planting them 3 weeks ago 19 are dying/dead.

I have attached close-up pictures.

Here is a time-lapse from Feb 1 to Feb 18 (since the transfer to 3 gallon buckets).



You can only see about half the willows. The periodic sagging was from watering; which should give you an idea of the frequency. Light cycle was add a few days in.

I bought another 24. I do not want to make the same mistake again! Let me know what you think the problem is.

Thanks!