Instructables user FriendOfHumanity has a little HOWTO for installing a windowbox planter on the handlebars of your bike. I dunno, I’d be worried about doing a faceplant (worse yet, if you planted chickpeas, you might falafel your bike) (I did that once and I falafel about it).
Bicycle Window Box- For the transient gardener.
(via Craft)