In this work we propose a new type of covering structures for greenhouses based on a tensegral conception with the aim of matching economical and sustainability requirements. We develop a minimal weight design procedure, considering all relevant load conditions. Strength constraints, local stability constraints and deflection constraints are imposed. Load conditions, stability, strength and deflection checks are carried out according to European technical rules. A global stability check of the optimized structure is performed a posteriori. The design variables are the joint positions, the cross section areas of members and the rest lengths of members, determining the initial prestress state. A relevant reduction of the structural weight with respect a previous design has been achieved. The effectiveness of our approach has been confirmed by a FEM analysis in which the whole greenhouse structure has been checked.