We demonstrate a quantitative framework for the study of yield‐density relationships of transplanted green asparagus (Asparagus officinalisL.). Such a framework is essential if new research is to make effective use of what is already known. We used quadratic equations to analyse data from 15 yield‐density studies with transplanted asparagus, in order to get indications of appropriate densities for new plantings in New Zealand and Western Samoa. In all instances the optimum density was close to or above the highest density used in the trial, so that optima were often poorly defined. We work with the density which gives 90% of the estimated optimum yield, which for practical application may be more realistic than the density which gives optimum yield. We give details of the methodology used for these estimates. Estimates of this 90% optimum, based on the cumulated yields over the first 3 years, varied from 8500 to 66 000 plants/ha. The optimum planting density estimated from cumulated yields to Year 3 gave an accurate estimate of optimum planting densities for cumulated yields to Year 7, and were substantially better for this purpose than cumulated yields to Year 2. No clear picture emerges of factors which may affect the optimum plant density for transplanted green asparagus, which clearly varies widely. There are too many factors which vary in an unsystematic manner between the different studies which we describe, or for which no information is given. We highlight deficiencies in trial planning and/or reporting which compromise the attempt to place individual trial results within a wider context. We make proposals for the conduct and reporting of future studies, which if followed will make the systematic overview of future trials more straightforward and productive.