They'll be rootbound long before 3 ft. esp. in such lil containers .
Do a lil more research , and how about some pics of the enviroment you have for them , we might be able to help a lil more w/ more than just a mental pic.

100 in a 5 x 5 will never happen , muchless that large . Usually as a rule you need 1 gal. of room in a pot per 1 foot of vert. plant desired .

Peace
Crispi :jointsmile: