A directly action-guiding experiment (trial) is an experiment performed to determine whether or to what extent some potential practical intervention has the desired effects. Clinical trials and agricultural field trials are prominent examples. Directly action-guiding experiments have been used in farming and various crafts since long before modern science. The trialability of a desired outcome is the (degree of) facility with which interventions that bring it about can be found and experimentally verified. This article introduces a framework for analyzing trialability in terms of eleven dimensions. The framework is applied to a comparison between trialability in traditional agriculture and traditional (prescientific) medicine. It turns out that trialability is in several respects greater in agriculture than in medicine. This finding can contribute to explaining why directly action-guiding experiments were common in agriculture long before they were introduced in medicine.