Experts and BHG readers answer.
Thanks for writing. There's not really anything you can do to encourage a bleeding heart to become more bushy other than to take good care of it and let it grow and fill out over time.
It will do best and grow fastest in moist, well-drained soil that's rich in organic matter (such as compost) and in dappled shade.
---Justin, Senior Garden Editor, BHG.com