Japanese Walnut, Siebold Walnut

This tree seems confused in this climate (zone 8b). It stays green until a hard freeze hits, then sends out new leaves very early and so...Read Moremetimes gets them blasted by a late frost. Any damage near the roots makes it send up a mess of suckers -- shades of the Ailanthus tree that is somewhat resembles. I have mine (and its multitudinous suckers and offsets, some ten feet away) in a sheltered area near my house, and I need to plant some out in more-exposed areas to see whether they will fare better in this possibly too-warm climate. I'd also like to see whether it will naturally hybridize with other members of the genus, or at least be pollinated by a buartnut (butternut/heartnut hybrid) I have.