Without the deets, I suggest they're dying from a combination of fertilizer toxicity combined with improper watering.
For your next run, DO NOT ADD ANY FERTILIZER. Theres plenty of nutrients in the dirt they're growing in, let them eat and deplete before you feed.
Next, let's talk about watering. You want the baby plant to grow roots, and the way you encourage it is to put water just out of the roots' grasp so that they will extend out to take their drink. So when you water, use something like an eye dropper and slowly introduce your water into the soil at the plant's drip line and never closer to the stem than that. As the water settles downward it will wicker out through the soil making it moist but not wet, except for where you placed your water.