Asparagus (Asparagus officinalis L.) acquires freezing tolerance during a period of fall acclimation when both photoperiod and temperature decrease. The above-ground vegetation may be important for sensing changing environmental conditions. Defoliation experiments were conducted over two years by removing fern throughout the fall , and evaluating crown metabolites and freezing tolerance at monthly intervals. Spring emergence and survival were also assessed in separate experiments . In the first year, mid-August defoliation decreased freezing tolerance, which was associated with diminished rhizome proline concentration and storage root fructan concentrations. All defoliation treatments in the second year increased freezing tolerance, possibly resulting from an interaction between defoliation and drought. Defoliation decreased spring vigor in both experiments; the response was proportional to the earliness of the treatment . Crowns of plants defoliated in mid-August had increasing proline concentrations during the fall suggesting the below-ground organs may have sensed soil temperature to cold acclimate