Do druids ever actively recruit to let people know they can join?
Short answer: In the Reformed Druids of North America (RDNA) you're not supposed to recruit members. Some other druid orders promote recruiting.
There was a time in the 1970s when a member of the RDNA priesthood was actively recruiting people as fast as he could in order to bring them into the Council so that he'd have a majority in his favor to pass his legislative ideas. He was specifically targeting people in the SCA (Society for Creative Anachronism) crowd.
His actions were a bit alarming to the members of the Council of Dalon Ap Landu as his proposals included major departure from the original spirit of Reformed Druidism. One of the Chairpersons emeritus of the Council suggested granting veto power to every member of the Council over any piece of legislation they deemed un-Reformed. They figured it would be too difficult to implement given that it would be an obvious move to prevent power grabs.
Luckily, there were many "recruits" who were in fact more sympathetic to the true spirit of Reformed Druidism, and the idea to get a supermajority was ultimately a failure. That led to the scheming member of the priesthood breaking away and form the New Reformed Druids of North America and the Schismatic Druids of North America. The latter served as the inspiration for the foundation of Ár nDraíocht Féin (ADF) which today is a neopagan branch of druidism that is a business and does actively recruit members.
Reformed Druidism still says that we should not recruit others, but to passively let them join because they want to of their own free will. However we are allowed to make ourselves discoverable through social media, indicating who we are without pushing for a call to action. That's tricky though, since groups under the RDNA (including Oakdale Grove) are accepting new members. We can't just say "join us!" So instead I word it something like "we are open to new membership" which is more neutral.