| | Re: First NPT, Issues
To answer your question, we are going to need some more information.
What type of soil did you use?
How deep is the soil? The capping material?
Personally, I suspect that the soil layer is either too thick (which would lead to anaerobic conditions which are detrimental to plants) or the soil was the incorrect type (i.e. had too much fertilizer in it which is bad...). Pictures are also helpful in determining the problem.