Is it planted? If you can make sure it is getting lots of sun exposure on the bare side and it should eventually fill in. Sunlight will stimulate any dormant branch buds to grow.
Welcome! I’m Margaret Roach, a leading garden writer for 25 years—at ‘Martha Stewart Living,’ ‘Newsday,’ and in three books. I host a public-radio podcast; I also lecture, plus hold tours at my 2.3-acre Hudson Valley (NY) Zone 5B garden, and always say no to chemicals and yes to great plants.