Former party manager Sancia Colgrave was preselected in January but did not announce her candidacy at the time as she awaited the outcome of an application for a government job.

In the end Ms Colgrave accepted neither. Last week she told the party she did not have the time to dedicate to a full-time campaign ahead of the May election.

"The Greens don't want to field candidates who are just names on a ballot paper," she said.

Ms Colgrave, who has decided to return to study, described Tasmania's Legislative Council as the "final frontier" for the Greens, which are represented on municipal councils, the state's House of Assembly and both levels of federal government.

Launceston is one of three upper house seats being contested this year and is likely to attract a large field of candidates hoping to capitalise on the absence of retiring incumbent Don Wing.

Liberal Party candidate Sam McQuestin launched his bid in July, followed by the Labor Party's Steve Bishop and independent Rosemary Armitage.

Former Launceston Chamber of Commerce chief executive Lou Clark said she would make a decision on whether to run for the seat by mid-March.

"I have received quite a bit of encouragement from people to consider it, so that's what I'm doing."

The Greens are expected to announce a new candidate in March.