In a field experiment conducted near Fort Collins, Colorado, we monitored seasonal trends in soluble carbohydrate (SC) concentrations in sugarbeet (Beta vulgaris). Three N fertility levels (0, 100, and 300 lb NIA) and two planting dates (April 22 and May 27) were imposed to study the SC concentration in four plant p arts (leaf blade, petiole, crown, and taproot) at biweekly intervals from June 27 to September 5, then a final sampling on October 18, 1977. We found that: 1) increasing N-fertilization decreased SC con centration (% of dry weight) when averaged for all plant parts; 2) roots were highest in SC concentration followed in decreasing order by crowns, petioles, and blades; 3) when averaged for all plant parts, the maximum rate of increase in SC concentration oc curred between June 27 and August 22; 4) early plant ing increased SC concentration in crowns and roots, but had little effect on SC concentration in blades or petioles; 5) SC concentrations were higher in early planted than later-planted sugarbeets until August 22, but thereafter there was no difference; 6) SC con centrations in blades and crowns increased linearly as the season advanced, but root SC was a maximum by August 22; 7) early planting increased the SC con centration in roots until August 10; thereafter, there was no difference between planting dates; and 8) plan ting date had variable effects on SC in the petioles, b ut SC in blades was unaffected by planting date.