Horticulture is fruit trees, olive orchards and growing of grapes for production of wine. Difference in crops separates agriculture and horticulture. Horticulture is a huge jump from just growing wheat and barley, which was grown in the neolythic. All of these things were being grown in the chalcolithic period. Also, not just the science of grafting makes horticulture remarkable, but also the multigenerational investment (requiring permanence, protection, maintenance) of olive orchards which take decades to mature. Also, development of vineyards and fruit trees takes forever.