If she sticks with the project I would bring some of the soil and water to a garden center/ aquatics store to see if they can check the soil and water for pH, nutrients etc. this way she can discuss more variables that may have contributed to the negative results. You can even purchase your own litmus paper and do pH testing at home (not sure about other at home tests as I don't garden but I know the testing is available at garden centers). Good Luck!! I am currently a laboratory manager and have worked in scientific research for my career and most experiments fail in science or at least need a lot of optimization, but you learn a lot from those less successful ventures.