"Growth momentum ebbed significantly" previous year, Destatis expert Albert Braakmann told reporters at a Berlin press conference.
Germany's export-dependent manufacturers are contending withsluggish foreign demand in light of a slowing world economy anduncertainty linked to trade disputes and Britain's decision toleave the European Union.
What are the latest figures?
GDP growth slumped to just 0.6pc in 2019, according to official agency Destatis, less than half the 1.5pc achieved in 2018 and well behind 2017's 2.5pc expansion.
Despite the drop, the Germany economy grew for a tenth year in a row - the longest period of growth since German reunification.
Separate data on Wednesday could highlight a surplus across all levels of government of up to 1.6 percent of GDP, Berenberg bank analysts predict, down from 1.9 percent in 2018.
Germany's economy grew at its slowest pace since 2013 past year as the trade war took a heavy toll on the nation's manufacturing industry.
The auto sector is also struggling to adjust to stricter emissions regulation and a shift to electric vehicles.
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Meanwhile, solid domestic consumption, buttressed by low unemployment, has helped keep the economy out of recession.
Some analysts pointed to Germany's massive surplus as a path forward to stimulate growth. OECD economist Nicola Brandt told Reuters.
The outlook for the coming year is reasonably positive, however, with the Bundesbank expecting 2020 growth to be about the same as 2019.
Merkel's government is facing increasing pressure both at home and overseas to relax its strict adherence to its no-new-debts policy known as the "black zero".
A fresh tug of war is already beginning between Merkel's conservative CDU party and their SPD centre-left junior coalition partners over how to spend the bonanza. "Instead, the surplus should be used to step up investment efforts in the well-known sectors: digitalisation, infrastructure and education", he added.
The SPD has been pushing for higher social spending and more investment - although SPD politician and Finance Minister Olaf Scholz has largely adhered to his predecessor Wolfgang Schäuble's "black zero" policies.
Possibly in response to such arguments, the government said Tuesday it had agreed to pump €62 billion euros into modernizing its rail network system, as part of a wider plan to incite commuters to opt for greener public transport options. Some analysts, however, believe it could rebound slightly to 1% due to several factors including there being more working days this year.