(hopefully this is in the correct category)

I have no prior experience of Cartography or mapping of any kind - save, and geocaching (which I accept are nothing alike - but I hope you better understand my starting postion).

I'm after some advice on software suitable to map a substantial garden - about 2 acres (so tiny in the world of maps). I'd like to accurately map this land including contours if possible, but mainly to catalogue the trees and other plants which reside within it.

Ideally I'd like to be able to manage this on-line, and (again) ideally from my own Apache server (and since I have some PHP knowlege that would be my preference) - it would be ace/brill (or "sick" as the youths say) if it could handle chronological changes too.

Since I obviously have no experience of this, any advice would be helpful - especially if somebody could balance my expectations against the task ahead of me.

thanks in advance,