An embodiment of the invention delivers water to plants of a specified type which reside in a quantity of soil. A condensing unit is operated at optimum intervals to condense water vapor in the air into water in liquid form. The condensed water is stored in a reservoir connected to an irrigation system, which can deliver water from the reservoir to each of the plants. A database is established that contains horticultural information, wherein the horticultural information comprises a set of values representing the water needed by plants of the specified type at different stages of growth. Estimates of soil moisture content are generated during a specified time period. Optimum watering intervals are computed during the specified time period, at least in part, as a function of the set of values contained in the horticultural database, and also as a function of the estimates of moisture content. The irrigation system is operated to deliver water to each plant during respective optimum watering intervals.
