I need ideas for my gardening club.

Start a marijuana farm so you can sell your crop for club fundraisers.

You could try getting people seeds and see if you can grow them. If that seems too challenging try garden gnomes instead.

Hold clothes optional days is a good idea. I know a naturist who goes nude in his allotment. Only one person has ever complained and he's been doing it for years.

When I was in college, there was a project that focused on planting around parking lots as a natural way of filtering out chemicals/toxins from all the vehicles.

It was called a run-off garden or something like that.

Make a grass couch

Plant trees everywhere !

Try filling it up with more foliage.

Try doing some topiary.