I was running through the advisory opinions on the LCB website re: a related issue and came across this:
While the Liquor Code states that limited wineries may only produce wine made from Pennsylvania grown agricultural commodities, this limitation has been deemed unenforceable as a result of the U.S. Supreme Court decision in the case of Granholm v. Heald, 544 U.S. 460 (2005), and the Pennsylvania federal court decision in Cutner v. Newman, 398 F. Supp.2d 389 (E.D. Pa. 2005), both involving legislative distinctions between in-state and out-of-state wineries. Accordingly, a limited winery licensee is not required to produce its wine using fruit from sources in Pennsylvania; rather, it may utilize fruit from other sources, whether from Pennsylvania or outside of Pennsylvania, although actual wine purchases from other limited wineries for subsequent resale are limited to no more than fifty percent (50%) of the purchasing winery’s previous year’s production. Therefore, as the law presently stands, a licensed limited winery may produce wine from agricultural commodities without regard to the source of such commodities. Thus, you would be permitted to import and use fruits and/or juice from out-of-state.
It reads like you can buy all the fruit and juice you want from other sources. But, actual wine from other limited wineries is limited to 50% of your production. Don't know if that helps.