How could the Jacksonians create a coalition between two such different interests as southern planters and northern workers?

The political coalition that undergirded the Democratic Party under Andrew Jackson was achieved as much through style as through appealing to specific interests. Jackson, through his political ally Martin Van Buren, forged alliances with working-class people in New York City in particular. There Van Buren eschewed the traditional strictures against campaigning publicly for higher office, and directly appealed to Irish immigrants, artisans, and so-called "mechanics," many of whom had experienced economic uncertainty as a result of the Market Revolution that swept through the country during the period. Van Buren also cultivated the support of some old-line Democratic-Republicans, patrician New York landholders who had always been suspicious of strong central government.
To ambitious Southerners, Jackson offered an expansionist foreign policy that targeted Native lands in the old Southwest. He also, at least in rhetoric, opposed a strong central government, a very popular position among many Southern planters, the most conservative of whom feared that a government that could use its power to enact public works, for example, could also move against slavery, and rumblings of abolitionism were already beginning to occur among educated Northerners who embraced the reform movements of the 1820s and 1830s.
To both working-class Northerners and agrarian Southerners, Jackson offered a plain-spoken style, an embrace of the "common man" that resonated with ordinary men who had gained the vote in many states throughout the nation. (Most states had dropped property-ownership requirements for voting in the early nineteenth century). In particular, he railed against privilege, which he saw as embodied in the Bank of the United States and in federal office-holding. His attacks on the bank while in office, as well as his moves to create a so-called "spoils system" were very popular with ordinary Americans.
http://www.digitalhistory.uh.edu/disp_textbook.cfm?smtID=2&psid=3542

https://millercenter.org/president/jackson

https://www.history.com/topics/19th-century/jacksonian-democracy

Jacksonian Democrats built a powerful, but unstable, coalition in the 1820s that involved two significantly different interest groups: northern workers and southern planters.
To reconcile the two factions of the Jacksonian coalition, Democrats pursued a program of degenerative policy design: policies that, in the words of Helen Ingram and Anne Schneider "perpetuate and aggravate divisions among citizens by providing them consistently with quite different treatment at the hands of government."
To curry favor of southern planters, the Jacksonians aggressively pursued policies of Indian removal through legislation like the Indian Removal Act and supported settlers’ preemption rights and cheap land prices. Jacksonians also, generally, supported slavery.
The support of northern workers, meanwhile, was secured through the imposition of high tariffs that kept importation of foreign products expensive and favored domestic manufacturing and production. As well, Andrew Jackson introduced a ten hour workday for some federal contract workers in the north.
http://sites.austincc.edu/caddis/jacksonian-democracy/

http://www.digitalhistory.uh.edu/era.cfm?eraID=5&smtID=2