From what i have read there are many varied symptoms ranging from yellowing leaves to main stem not developing fully with fragile branches.
Sings of over feeding to deficiencies and anything in between, pith in the stems can be eroded.
Sorry forgot it's a homebox you are using..
Homebox claim their tents were not affected by out gassing as they use a different plastic (polyethylene)l to the other brands affected
a lot of the affected tents seem to be constructed using PVC.
There is a better explanation and a link to the test report carried out on hombox tents on their website.
Good luck.