Where does سبز come from? (Wiktionary has no etymological information.) Urdu and Hindhi have the word "sabzi", which is derived from it, but is there a PIE root from which this derives, or is Old Persian the furthest back we can trace it?
The origin of sabz is debated. One suggestion is that it derives from Iranian *spar “to blossom, to sprout”, and is thus cognate with Latin spargo, English sprig etc. The derivation is phonologically complex. If you have access to a university library look up the complicated argumentation by W.B. Henning, Bulletin of the School of Oriental and African Studies, 1947, pp. 46 (bottom) to 47, (also in his Collected papers, vol. 2, pp. 280-1).