Gravis Marketing has released a poll for Indiana 2018 general elections. See question eleven, in which the pollsters asked about the nominees of the Green and Libertarian Parties as well as the major party nominees. The poll shows 10% for the Libertarian and 4% for the Green.
There is no assurance that the Green Party will even be on the ballot in 2018. It is petitioning, but it has never before succeeded in getting on the Indiana ballot for statewide office. The requirement this year is 26,700 signatures. Thanks to Michael for the link.