Asparagus (Asparagus officinalis L.) acquires freezing tolerance during a period of fall acclimation when both photoperiod and temperature decrease. The above-ground vegetative growth may be important for sensing changing environmental conditions and translocating compounds to the below-ground crown. Defoliation experiments, repeated over 2 yr, were conducted by removing fern in mid-August, -September, and -October and evaluating crown metabolites and LT₅₀, the temperature at which 50% of plants die, at monthly intervals to mid-November. Spring emergence and vigor were also assessed in separate experiments. In the first year, only mid-August defoliation affected LT₅₀ values, decreasing freezing tolerance, which was associated with diminished rhizome proline concentration and storage root low- and high-molecular-weight fructan concentrations. All defoliation treatments in the second year decreased LT₅₀ values, or increased freezing tolerance, possibly resulting from an interaction between defoliation and drought which increased rhizome sucrose concentrations. Defoliation decreased spring vigor in both experiments; the response was proportional to the earliness of the treatment and associated with rhizome and storage root fructan levels. Crowns of plants defoliated in mid-August had increasing proline concentrations during the fall, similar to control plants, suggesting the below-ground organs may have sensed soil temperature to cold acclimate. Autumn defoliation to control disease, harvest seed, or implement other cultural practices can reduce vigor and likely attenuate long-term performance of a plantation.