The objective of this study was to determine the effects of storage length and microbial inoculation on the fermentation profile, N fractions, and ruminal in situ starch disappearance of whole-plant corn silage. Whole-plant corn (33.3 ± 1.0% DM) was ensiled for 0, 30, 60, 90 or 120 d in quintuplicate vacuum-sealed pouches untreated (CON) or inoculated with: Lactobacillus plantarum CH6072 at 1 × 10⁵ and Enterococcus faecium CH212 at 5 × 10⁴ cfu/g of fresh forage (LPEF); L. buchneri LB1819 and Lactococcus lactis O224 at 1.5 × 10⁵ cfu/g (LBLL); and E. faecium CH212 at 1.5 × 10⁵ cfu/g (EF). Data were analyzed as a completely randomized design with a 4 × 5 factorial arrangement of treatments using PROC GLIMMIX. The model included microbial inoculation, storage length, and their interactions as fixed effects. Silage pH was greater for LBLL compared with the other treatments (P < 0.01). Total acids (as % of DM) were greatest in LPEF (7.27 ± 0.12), intermediate in CON and LBLL (7.15 and 6.83 ± 0.12, respectively), and lowest in EF (6.71 ± 0.12; P < 0.001). Ammonia-N (as % of N) was greatest in CON (5.27 ± 0.08), intermediate in LPEF and LBLL (4.87 ± 0.08 for both), and lowest in EF (4.62 ± 0.08; P < 0.01). Silage pH decreased quadratically as storage length increased from 30 to 120 d (P < 0.01). Ammonia-N increased quadratically with storage length (P < 0.01). Interactions between microbial inoculation and storage length were observed for lactic acid (P = 0.05), acetic acid (P = 0.09), and ruminal in situ starch disappearance (P = 0.01). Lactic acid concentrations were reduced with LBLL compared with the other treatments at 30, 90, and 120 d. Acetic acid concentrations were similar between all treatments at 30 d, but were greater for LBLL after 60 d. Starch disappearance was reduced for CON compared with the other treatments at 60 and 90 d but was similar across all treatments at 120 d. Although fermentation profile was improved with the use of microbial inoculants, minimal benefits of inoculants on starch disappearance were observed.