The match was sent off court in early evening, with just 50 minutes of cumulative playing time since the intended start more than six and a half hours earlier.
Thiem and Kohlschreiber will resume action on Monday.
The final is a re-run of the Munich final of six weeks ago, won by Kohlschreiber during a week when April snow fell on matches in the Bavarian capital.
Thiem, who moved into the ATP top 10 this week after a French Open semi-final performance, owns three titles in 2016 -- winning Buenos Aires, Acapulco and Nice.
The 22-year-old, who saved two match points as he knocked out Roger Federer in the quarter-finals, is bidding to become the first man this season to claim trophies on three different surfaces (clay, hardcourt and now grass).
Thiem has never beaten Kohlschreiber, also losing to him in a Kitzbuehel semi-final last summer on clay.
The Stuttgart tournament switched to grass last season under the supervision of All England Club groundsmen in order to join the expanded three-week build-up to Wimbledon.
Rafael Nadal won the inaugural title.